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Message-ID: <akpv4md6r5yavgqey2codbxcywlnnxvopx3oy5fkugz6oqj656@cac7tomc4dog>
Date: Wed, 5 Nov 2025 11:38:53 +0000
From: Adrián Larumbe <adrian.larumbe@...labora.com>
To: Lukas Zapolskas <lukas.zapolskas@....com>
Cc: dri-devel@...ts.freedesktop.org, nd@....com,
Boris Brezillon <boris.brezillon@...labora.com>, Steven Price <steven.price@....com>,
Liviu Dudau <liviu.dudau@....com>, Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 5/7] drm/panthor: Implement the counter sampler and
sample handling
On 30.08.2025 16:58, Adrián Larumbe wrote:
> On 25.07.2025 15:57, Lukas Zapolskas wrote:
> > From: Adrián Larumbe <adrian.larumbe@...labora.com>
> >
> > The sampler aggregates counter and set requests coming from userspace
> > and mediates interactions with the FW interface, to ensure that user
> > sessions cannot override the global configuration.
> >
> > From the top-level interface, the sampler supports two different types
> > of samples: clearing samples and regular samples. Clearing samples are
> > a special sample type that allow for the creation of a sampling
> > baseline, to ensure that a session does not obtain counter data from
> > before its creation.
> >
> > Upon receipt of a relevant interrupt, corresponding to one of the
> > three relevant bits of the GLB_ACK register, the sampler takes any
> > samples that occurred, and, based on the insert and extract indices,
> > accumulates them to an internal storage buffer after zero-extending
> > the counters from the 32-bit counters emitted by the hardware to
> > 64-bit counters for internal accumulation.
> >
> > When the performance counters are enabled, the FW ensures no counter
> > data is lost when entering and leaving non-counting regions by
> > producing automatic samples that do not correspond to a
> > GLB_REQ.PRFCNT_SAMPLE request. Such regions may be per hardware unit,
> > such as when a shader core powers down, or global. Most of these
> > events do not directly correspond to session sample requests, so any
> > intermediary counter data must be stored into a temporary
> > accumulation buffer.
> >
> > If there are sessions waiting for a sample, this accumulated buffer
> > will be taken, and emitted for each waiting client. During this phase,
> > information like the timestamps of sample request and sample emission,
> > type of the counter block and block index annotations are added to the
> > sample header and block headers. If no sessions are waiting for
> > a sample, this accumulation buffer is kept until the next time a
> > sample is requested.
> >
> > Special handling is needed for the PRFCNT_OVERFLOW interrupt, which is
> > an indication that the internal sample handling rate was insufficient.
> >
> > The sampler also maintains a buffer descriptor indicating the
> > structure of a firmware sample, since neither the firmware nor the
> > hardware give any indication of the sample structure, only that it
> > is composed out of three parts:
> > - the metadata is an optional initial counter block on supporting
> > firmware versions that contains a single counter, indicating the
> > reason a sample was taken when entering global non-counting regions.
> > This is used to provide coarse-grained information about why a
> > sample was taken to userspace, to help userspace interpret
> > variations in counter magnitude (the handling for this will be
> > implemented in another patch series).
> > - the firmware component of the sample is composed out of a global
> > firmware counter block on supporting firmware versions.
> > - the hardware component is the most sizeable of the three and
> > contains a block of counters for each of the underlying hardware
> > resources. It has a fixed structure that is described in the
> > architecture specification, and contains the command stream
> > hardware block(s), the tiler block(s), the MMU and L2 blocks
> > (collectively named the memsys blocks) and the shader core blocks,
> > in that order.
> > The structure of this buffer changes based on the firmware and
> > hardware combination, but is constant on a single system.
> >
> > This buffer descriptor also handles the sparseness of the shader cores,
> > wherein the physical core mask contains holes, but the memory allocated
> > for it is done based on the position of the most significant bit. In
> > cases with highly sparse core masks, this means that a lot of shader
> > counter blocks are empty, and must be skipped.
> >
> > The number of ring buffer slots is configurable through module param
> > to allow for a lower memory footprint on memory constrained systems.
> >
> > Signed-off-by: Adrián Larumbe <adrian.larumbe@...labora.com>
> > Co-developed-by: Lukas Zapolskas <lukas.zapolskas@....com>
> > Signed-off-by: Lukas Zapolskas <lukas.zapolskas@....com>
> > ---
> > drivers/gpu/drm/panthor/panthor_fw.c | 6 +
> > drivers/gpu/drm/panthor/panthor_fw.h | 6 +-
> > drivers/gpu/drm/panthor/panthor_perf.c | 1061 +++++++++++++++++++++++-
> > drivers/gpu/drm/panthor/panthor_perf.h | 2 +
> > 4 files changed, 1068 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/panthor/panthor_fw.c b/drivers/gpu/drm/panthor/panthor_fw.c
> > index 36f1034839c2..c3e1e5ed4f9c 100644
> > --- a/drivers/gpu/drm/panthor/panthor_fw.c
> > +++ b/drivers/gpu/drm/panthor/panthor_fw.c
> > @@ -22,6 +22,7 @@
> > #include "panthor_gem.h"
> > #include "panthor_gpu.h"
> > #include "panthor_mmu.h"
> > +#include "panthor_perf.h"
> > #include "panthor_regs.h"
> > #include "panthor_sched.h"
> >
> > @@ -989,9 +990,12 @@ static void panthor_fw_init_global_iface(struct panthor_device *ptdev)
> >
> > /* Enable interrupts we care about. */
> > glb_iface->input->ack_irq_mask = GLB_CFG_ALLOC_EN |
> > + GLB_PERFCNT_SAMPLE |
> > GLB_PING |
> > GLB_CFG_PROGRESS_TIMER |
> > GLB_CFG_POWEROFF_TIMER |
> > + GLB_PERFCNT_THRESHOLD |
> > + GLB_PERFCNT_OVERFLOW |
> > GLB_IDLE_EN |
> > GLB_IDLE;
> >
> > @@ -1022,6 +1026,8 @@ static void panthor_job_irq_handler(struct panthor_device *ptdev, u32 status)
> > return;
> >
> > panthor_sched_report_fw_events(ptdev, status);
> > +
> > + panthor_perf_report_irq(ptdev, status);
> > }
> > PANTHOR_IRQ_HANDLER(job, JOB, panthor_job_irq_handler);
> >
> > diff --git a/drivers/gpu/drm/panthor/panthor_fw.h b/drivers/gpu/drm/panthor/panthor_fw.h
> > index 8bcb933fa790..5a561e72e88b 100644
> > --- a/drivers/gpu/drm/panthor/panthor_fw.h
> > +++ b/drivers/gpu/drm/panthor/panthor_fw.h
> > @@ -198,6 +198,7 @@ struct panthor_fw_global_control_iface {
> > u32 group_num;
> > u32 group_stride;
> > #define GLB_PERFCNT_FW_SIZE(x) ((((x) >> 16) << 8))
> > +#define GLB_PERFCNT_HW_SIZE(x) (((x) & GENMASK(15, 0)) << 8)
> > u32 perfcnt_size;
> > u32 instr_features;
> > #define PERFCNT_FEATURES_MD_SIZE(x) (((x) & GENMASK(3, 0)) << 8)
> > @@ -210,7 +211,7 @@ struct panthor_fw_global_input_iface {
> > #define GLB_CFG_ALLOC_EN BIT(2)
> > #define GLB_CFG_POWEROFF_TIMER BIT(3)
> > #define GLB_PROTM_ENTER BIT(4)
> > -#define GLB_PERFCNT_EN BIT(5)
> > +#define GLB_PERFCNT_ENABLE BIT(5)
> > #define GLB_PERFCNT_SAMPLE BIT(6)
> > #define GLB_COUNTER_EN BIT(7)
> > #define GLB_PING BIT(8)
> > @@ -243,6 +244,9 @@ struct panthor_fw_global_input_iface {
> > u64 perfcnt_base;
> > u32 perfcnt_extract;
> > u32 reserved3[3];
> > +#define GLB_PERFCNT_CONFIG_SIZE(x) ((x) & GENMASK(7, 0))
> > +#define GLB_PERFCNT_CONFIG_SET(x) (((x) & GENMASK(1, 0)) << 8)
> > +#define GLB_PERFCNT_METADATA_ENABLE BIT(10)
> > u32 perfcnt_config;
> > u32 perfcnt_csg_select;
> > u32 perfcnt_fw_enable;
> > diff --git a/drivers/gpu/drm/panthor/panthor_perf.c b/drivers/gpu/drm/panthor/panthor_perf.c
> > index d1f984b3302a..fd16039d9244 100644
> > --- a/drivers/gpu/drm/panthor/panthor_perf.c
> > +++ b/drivers/gpu/drm/panthor/panthor_perf.c
> > @@ -10,6 +10,9 @@
> >
> > #include "panthor_device.h"
> > #include "panthor_fw.h"
> > +#include "panthor_gem.h"
> > +#include "panthor_gpu.h"
> > +#include "panthor_mmu.h"
> > #include "panthor_perf.h"
> > #include "panthor_regs.h"
> >
> > @@ -20,6 +23,81 @@
> > */
> > #define PANTHOR_PERF_EM_BITS (BITS_PER_TYPE(u64) * 2)
> >
> > +/**
> > + * PANTHOR_CTR_TIMESTAMP_LO - The first architecturally mandated counter of every block type
> > + * contains the low 32-bits of the TIMESTAMP value.
> > + */
> > +#define PANTHOR_CTR_TIMESTAMP_LO (0)
> > +
> > +/**
> > + * PANTHOR_CTR_TIMESTAMP_HI - The register offset containinig the high 32-bits of the TIMESTAMP
> > + * value.
> > + */
> > +#define PANTHOR_CTR_TIMESTAMP_HI (1)
> > +
> > +/**
> > + * PANTHOR_CTR_PRFCNT_EN - The register offset containing the enable mask for the enabled counters
> > + * that were written to memory.
> > + */
> > +#define PANTHOR_CTR_PRFCNT_EN (2)
> > +
> > +/**
> > + * PANTHOR_HEADER_COUNTERS - The first four counters of every block type are architecturally
> > + * defined to be equivalent. The fourth counter is always reserved,
> > + * and should be zero and as such, does not have a separate define.
> > + *
> > + * These are the only four counters that are the same between different
> > + * blocks and are consistent between different architectures.
> > + */
> > +#define PANTHOR_HEADER_COUNTERS (4)
> > +
> > +/**
> > + * PANTHOR_CTR_SAMPLE_REASON - The metadata block has a single value in position three which
> > + * indicates the reason a sample was taken.
> > + */
> > +#define PANTHOR_CTR_SAMPLE_REASON (3)
> > +
> > +/**
> > + * PANTHOR_HW_COUNTER_SIZE - The size of a hardware counter in the FW ring buffer.
> > + */
> > +#define PANTHOR_HW_COUNTER_SIZE (sizeof(u32))
> > +
> > +/**
> > + * PANTHOR_PERF_RINGBUF_SLOTS_MIN - The minimum permitted number of slots in the Panthor perf
> > + * ring buffer.
> > + */
> > +#define PANTHOR_PERF_RINGBUF_SLOTS_MIN (16)
> > +
> > +/**
> > + * PANTHOR_PERF_RINGBUF_SLOTS_MAX - The maximum permitted number of slots in the Panthor perf
> > + * ring buffer.
> > + */
> > +#define PANTHOR_PERF_RINGBUF_SLOTS_MAX (256)
> > +
> > +static unsigned int perf_ringbuf_slots = 32;
> > +
> > +static int perf_ringbuf_slots_set(const char *val, const struct kernel_param *kp)
> > +{
> > + unsigned int slots;
> > + int ret = kstrtouint(val, 0, &slots);
> > +
> > + if (ret)
> > + return ret;
> > +
> > + if (!is_power_of_2(slots))
> > + return -EINVAL;
> > +
> > + return param_set_uint_minmax(val, kp, 16, 256);
> > +}
> > +
> > +static const struct kernel_param_ops perf_ringbuf_ops = {
> > + .set = perf_ringbuf_slots_set,
> > + .get = param_get_uint,
> > +};
> > +module_param_cb(perf_ringbuf_slots, &perf_ringbuf_ops, &perf_ringbuf_slots, 0400);
> > +MODULE_PARM_DESC(perf_ringbuf_slots,
> > + "Power of two slots allocated for the Panthor perf kernel-FW ringbuffer");
> > +
> > enum panthor_perf_session_state {
> > /** @PANTHOR_PERF_SESSION_ACTIVE: The session is active and can be used for sampling. */
> > PANTHOR_PERF_SESSION_ACTIVE = 0,
> > @@ -65,6 +143,116 @@ enum session_sample_type {
> > SAMPLE_TYPE_REGULAR,
> > };
> >
> > +struct panthor_perf_buffer_descriptor {
> > + /**
> > + * @block_size: The size of a single block in the FW ring buffer, equal to
> > + * sizeof(u32) * counters_per_block.
> > + */
> > + size_t block_size;
> > +
> > + /**
> > + * @buffer_size: The total size of the buffer, equal to (#hardware blocks +
> > + * #firmware blocks) * block_size.
> > + */
> > + size_t buffer_size;
> > +
> > + /**
> > + * @available_blocks: Bitmask indicating the blocks supported by the hardware and firmware
> > + * combination. Note that this can also include blocks that will not
> > + * be exposed to the user.
> > + */
> > + DECLARE_BITMAP(available_blocks, DRM_PANTHOR_PERF_BLOCK_MAX);
> > + struct {
> > + /** @offset: Starting offset of a block of type @type in the FW ringbuffer. */
> > + size_t offset;
> > +
> > + /** @block_count: Number of blocks of the given @type, starting at @offset. */
> > + size_t block_count;
> > +
> > + /** @phys_mask: Bitmask of the physically available blocks. */
> > + u64 phys_mask;
> > + } blocks[DRM_PANTHOR_PERF_BLOCK_MAX];
> > +};
> > +
> > +/**
> > + * struct panthor_perf_sampler - Interface to de-multiplex firmware interaction and handle
> > + * global interactions.
> > + */
> > +struct panthor_perf_sampler {
> > + /**
> > + * @enabled_clients: The number of clients concurrently requesting samples. To ensure that
> > + * one client cannot deny samples to another, we must ensure that clients
> > + * are effectively reference counted.
> > + */
> > + atomic_t enabled_clients;
> > +
> > + /**
> > + * @sample_handled: Synchronization point between the interrupt bottom half and the
> > + * main sampler interface. Must be re-armed solely on a new request
> > + * coming to the sampler.
> > + */
> > + struct completion sample_handled;
> > +
> > + /** @rb: Kernel BO in the FW AS containing the sample ringbuffer. */
> > + struct panthor_kernel_bo *rb;
> > +
> > + /**
> > + * @sample_slots: Number of slots for samples in the FW ringbuffer. Could be static,
> > + * but may be useful to customize for low-memory devices.
> > + */
> > + size_t sample_slots;
> > +
> > + /** @em: Combined enable mask for all of the active sessions. */
> > + struct panthor_perf_enable_masks *em;
> > +
> > + /**
> > + * @desc: Buffer descriptor for a sample in the FW ringbuffer. Note that this buffer
> > + * at current time does some interesting things with the zeroth block type. On
> > + * newer FW revisions, the first counter block of the sample is the METADATA block,
> > + * which contains a single value indicating the reason the sample was taken (if
> > + * any). This block must not be exposed to userspace, as userspace does not
> > + * have sufficient context to interpret it. As such, this block type is not
> > + * added to the uAPI, but we still use it in the kernel.
> > + */
> > + struct panthor_perf_buffer_descriptor desc;
> > +
> > + /**
> > + * @sample: Pointer to an upscaled and annotated sample that may be emitted to userspace.
> > + * This is used both as an intermediate buffer to do the zero-extension of the
> > + * 32-bit counters to 64-bits and as a storage buffer in case the sampler
> > + * requests an additional sample that was not requested by any of the top-level
> > + * sessions (for instance, when changing the enable masks).
> > + */
> > + u8 *sample;
> > +
> > + /**
> > + * @sampler_lock: Lock used to guard the list of sessions and the sampler configuration.
> > + * In particular, it guards the @session_list and the @em.
> > + */
> > + struct mutex sampler_lock;
> > +
> > + /** @session_list: List of all sessions. */
> > + struct list_head session_list;
> > +
> > + /** @pend_lock: Lock used to guard the list of sessions with pending samples. */
> > + spinlock_t pend_lock;
> > +
> > + /** @pending_samples: List of sessions requesting samples. */
> > + struct list_head pending_samples;
> > +
> > + /** @sample_requested: A sample has been requested. */
> > + bool sample_requested;
> > +
> > + /** @set_config: The set that will be configured onto the hardware. */
> > + u8 set_config;
> > +
> > + /**
> > + * @ptdev: Backpointer to the Panthor device, needed to ring the global doorbell and
> > + * interface with FW.
> > + */
> > + struct panthor_device *ptdev;
> > +};
> > +
> > struct panthor_perf_session {
> > DECLARE_BITMAP(state, PANTHOR_PERF_SESSION_MAX);
> >
> > @@ -186,6 +374,9 @@ struct panthor_perf {
> > * @sessions: Global map of sessions, accessed by their ID.
> > */
> > struct xarray sessions;
> > +
> > + /** @sampler: FW control interface. */
> > + struct panthor_perf_sampler sampler;
> > };
> >
> > static size_t get_annotated_block_size(size_t counters_per_block)
> > @@ -255,6 +446,23 @@ static struct panthor_perf_enable_masks *panthor_perf_create_em(struct drm_panth
> > return em;
> > }
> >
> > +static void panthor_perf_em_add(struct panthor_perf_enable_masks *const dst_em,
> > + const struct panthor_perf_enable_masks *const src_em)
> > +{
> > + size_t i = 0;
> > +
> > + for (i = DRM_PANTHOR_PERF_BLOCK_FIRST; i <= DRM_PANTHOR_PERF_BLOCK_LAST; i++)
> > + bitmap_or(dst_em->mask[i], dst_em->mask[i], src_em->mask[i], PANTHOR_PERF_EM_BITS);
> > +}
> > +
> > +static void panthor_perf_em_zero(struct panthor_perf_enable_masks *em)
> > +{
> > + size_t i = 0;
> > +
> > + for (i = DRM_PANTHOR_PERF_BLOCK_FIRST; i <= DRM_PANTHOR_PERF_BLOCK_LAST; i++)
> > + bitmap_zero(em->mask[i], PANTHOR_PERF_EM_BITS);
> > +}
> > +
> > static u64 session_read_extract_idx(struct panthor_perf_session *session)
> > {
> > const u64 slots = session->ringbuf_slots;
> > @@ -265,6 +473,12 @@ static u64 session_read_extract_idx(struct panthor_perf_session *session)
> > return smp_load_acquire(&session->control->extract_idx) % slots;
> > }
> >
> > +static void session_write_insert_idx(struct panthor_perf_session *session, u64 idx)
> > +{
> > + /* Userspace needs the insert index to know where to look for the sample. */
> > + smp_store_release(&session->control->insert_idx, idx);
> > +}
> > +
> > static u64 session_read_insert_idx(struct panthor_perf_session *session)
> > {
> > const u64 slots = session->ringbuf_slots;
> > @@ -352,6 +566,758 @@ static struct panthor_perf_session *session_find(struct panthor_file *pfile,
> > return session;
> > }
> >
> > +static u32 compress_enable_mask(u32 counters, const unsigned long *const src)
> > +{
> > + size_t i;
> > + u32 result = 0;
> > + const unsigned long ctr_per_bit = counters / BITS_PER_TYPE(u32);
> > +
> > + for_each_set_bit(i, src, counters) {
> > + const unsigned long pos = div_u64(i, ctr_per_bit);
> > +
> > + result |= BIT(pos);
> > + }
> > +
> > + return result;
> > +}
> > +
> > +static void expand_enable_mask(u32 counters, u32 em, unsigned long *const dst)
> > +{
> > + size_t i;
> > + const unsigned long ctrs_per_bit = counters / BITS_PER_TYPE(u32);
> > + DECLARE_BITMAP(emb, BITS_PER_TYPE(u32));
> > +
> > + bitmap_from_arr32(emb, &em, BITS_PER_TYPE(u32));
> > +
> > + for_each_set_bit(i, emb, BITS_PER_TYPE(u32))
> > + bitmap_set(dst, i * ctrs_per_bit, ctrs_per_bit);
> > +}
> > +
> > +/**
> > + * panthor_perf_block_data - Identify the block index and type based on the offset.
> > + *
> > + * @desc: FW buffer descriptor.
> > + * @offset: The current offset being examined.
> > + * @idx: Pointer to an output index.
> > + * @type: Pointer to an output block type.
> > + *
> > + * To disambiguate different types of blocks as well as different blocks of the same type,
> > + * the offset into the FW ringbuffer is used to uniquely identify the block being considered.
> > + *
> > + * In the future, this is a good time to identify whether a block will be empty,
> > + * allowing us to short-circuit its processing after emitting header information.
> > + *
> > + * Return: True if the current block is available, false otherwise.
> > + */
> > +static bool panthor_perf_block_data(struct panthor_perf_buffer_descriptor *const desc,
> > + size_t offset, u32 *const idx,
> > + enum drm_panthor_perf_block_type *type)
> > +{
> > + unsigned long id;
> > +
> > + for_each_set_bit(id, desc->available_blocks, DRM_PANTHOR_PERF_BLOCK_LAST) {
> > + const size_t block_start = desc->blocks[id].offset;
> > + const size_t block_count = desc->blocks[id].block_count;
> > + const size_t block_end = desc->blocks[id].offset +
> > + desc->block_size * block_count;
> > +
> > + if (!block_count)
> > + continue;
> > +
> > + if (offset >= block_start && offset < block_end) {
> > + const unsigned long phys_mask[] = {
> > + BITMAP_FROM_U64(desc->blocks[id].phys_mask),
> > + };
> > + const size_t pos =
> > + div_u64(offset - desc->blocks[id].offset, desc->block_size);
> > +
> > + *type = id;
> > +
> > + if (test_bit(pos, phys_mask)) {
> > + const u64 mask = GENMASK_ULL(pos, 0);
> > + const u64 zeroes = ~desc->blocks[id].phys_mask & mask;
> > +
> > + *idx = pos - hweight64(zeroes);
> > + return true;
> > + }
> > + return false;
> > + }
> > + }
> > +
> > + return false;
> > +}
> > +
> > +static u32 panthor_perf_handle_sample(struct panthor_device *ptdev, u32 extract_idx, u32 insert_idx)
> > +{
> > + struct panthor_perf *perf = ptdev->perf;
> > + struct panthor_perf_sampler *sampler = &ptdev->perf->sampler;
> > + const size_t ann_block_size =
> > + get_annotated_block_size(ptdev->perf_info.counters_per_block);
> > + u32 i;
> > +
> > + for (i = extract_idx; i != insert_idx; i++) {
> > + u32 slot = i % sampler->sample_slots;
> > + u8 *fw_sample = (u8 *)sampler->rb->kmap + slot * sampler->desc.buffer_size;
> > +
> > + for (size_t fw_off = 0, ann_off = ptdev->perf_info.sample_header_size;
> > + fw_off < sampler->desc.buffer_size;
> > + fw_off += sampler->desc.block_size)
> > +
> > + {
> > + u32 idx = 0;
> > + enum drm_panthor_perf_block_type type = 0;
> > + DECLARE_BITMAP(expanded_em, PANTHOR_PERF_EM_BITS);
> > + struct panthor_perf_counter_block *blk =
> > + (typeof(blk))(perf->sampler.sample + ann_off);
> > + u32 *const block = (u32 *)(fw_sample + fw_off);
> > + const u32 prfcnt_en = block[PANTHOR_CTR_PRFCNT_EN];
> > +
> > + if (!panthor_perf_block_data(&sampler->desc, fw_off, &idx, &type))
> > + continue;
> > +
> > + /**
> > + * TODO Data from the metadata block must be used to populate the
> > + * block state information.
> > + */
> > + if (type == DRM_PANTHOR_PERF_BLOCK_METADATA) {
> > + /*
> > + * The host must clear the SAMPLE_REASON to acknowledge it has
> > + * consumed the sample.
> > + */
> > + block[PANTHOR_CTR_SAMPLE_REASON] = 0;
> > + continue;
> > + }
> > +
> > + expand_enable_mask(ptdev->perf_info.counters_per_block,
> > + prfcnt_en, expanded_em);
> > +
> > + blk->header = (struct drm_panthor_perf_block_header) {
> > + .clock = 0,
> > + .block_idx = idx,
> > + .block_type = type,
> > + .block_states = DRM_PANTHOR_PERF_BLOCK_STATE_UNKNOWN
> > + };
> > + bitmap_to_arr64(blk->header.enable_mask, expanded_em, PANTHOR_PERF_EM_BITS);
> > +
> > + /*
> > + * The four header counters must be treated differently, because they are
> > + * not additive. For the fourth, the assignment does not matter, as it
> > + * is reserved and should be zero.
> > + */
> > + blk->counters[PANTHOR_CTR_TIMESTAMP_LO] = block[PANTHOR_CTR_TIMESTAMP_LO];
> > + blk->counters[PANTHOR_CTR_TIMESTAMP_HI] = block[PANTHOR_CTR_TIMESTAMP_HI];
> > + blk->counters[PANTHOR_CTR_PRFCNT_EN] = block[PANTHOR_CTR_PRFCNT_EN];
> > +
> > + /*
> > + * The host must clear PRFCNT_EN to acknowledge it has consumed the sample.
> > + */
> > + block[PANTHOR_CTR_PRFCNT_EN] = 0;
> > +
> > + for (size_t k = PANTHOR_HEADER_COUNTERS;
> > + k < ptdev->perf_info.counters_per_block;
> > + k++)
> > + blk->counters[k] += block[k];
> > +
> > + ann_off += ann_block_size;
> > + }
> > + }
> > +
> > + return i;
> > +}
> > +
> > +static size_t panthor_perf_get_fw_reported_size(struct panthor_device *ptdev)
> > +{
> > + struct panthor_fw_global_iface *glb_iface = panthor_fw_get_glb_iface(ptdev);
> > +
> > + size_t fw_size = GLB_PERFCNT_FW_SIZE(glb_iface->control->perfcnt_size);
> > + size_t hw_size = GLB_PERFCNT_HW_SIZE(glb_iface->control->perfcnt_size);
> > + size_t md_size = PERFCNT_FEATURES_MD_SIZE(glb_iface->control->perfcnt_features);
> > +
> > + return md_size + fw_size + hw_size;
> > +}
> > +
> > +#define PANTHOR_PERF_SET_BLOCK_DESC_DATA(__desc, __type, __blk_count, __phys_mask, __offset) \
> > + ({ \
> > + (__desc)->blocks[(__type)].offset = (__offset); \
> > + (__desc)->blocks[(__type)].block_count = (__blk_count); \
> > + (__desc)->blocks[(__type)].phys_mask = (__phys_mask); \
> > + if ((__blk_count)) \
> > + set_bit((__type), (__desc)->available_blocks); \
> > + (__offset) + ((__desc)->block_size) * (__blk_count); \
> > + })
> > +
> > +static size_t get_reserved_sc_blocks(struct panthor_device *ptdev)
> > +{
> > + const u64 sc_mask = ptdev->gpu_info.shader_present;
> > +
> > + return fls64(sc_mask);
> > +}
> > +
> > +#define BLK_MASK(x) GENMASK_ULL((x) - 1, 0)
> > +
> > +static u64 get_sc_mask(struct panthor_device *ptdev)
> > +{
> > + const u64 sc_mask = ptdev->gpu_info.shader_present;
> > +
> > + return BLK_MASK(hweight64(sc_mask));
> > +}
> > +
> > +static int panthor_perf_setup_fw_buffer_desc(struct panthor_device *ptdev,
> > + struct panthor_perf_sampler *sampler)
> > +{
> > + const struct drm_panthor_perf_info *const info = &ptdev->perf_info;
> > + const size_t block_size = info->counters_per_block * PANTHOR_HW_COUNTER_SIZE;
> > + struct panthor_perf_buffer_descriptor *desc = &sampler->desc;
> > + const size_t fw_sample_size = panthor_perf_get_fw_reported_size(ptdev);
> > + size_t offset = 0;
> > +
> > + desc->block_size = block_size;
> > +
> > + for (enum drm_panthor_perf_block_type type = 0; type < DRM_PANTHOR_PERF_BLOCK_MAX; type++) {
> > + switch (type) {
> > + case DRM_PANTHOR_PERF_BLOCK_METADATA:
> > + if (info->flags & DRM_PANTHOR_PERF_BLOCK_STATES_SUPPORT)
> > + offset = PANTHOR_PERF_SET_BLOCK_DESC_DATA(desc, type, 1,
> > + BLK_MASK(1), offset);
> > + break;
> > + case DRM_PANTHOR_PERF_BLOCK_FW:
> > + offset = PANTHOR_PERF_SET_BLOCK_DESC_DATA(desc, type, info->fw_blocks,
> > + BLK_MASK(info->fw_blocks),
> > + offset);
> > + break;
> > + case DRM_PANTHOR_PERF_BLOCK_CSHW:
> > + offset = PANTHOR_PERF_SET_BLOCK_DESC_DATA(desc, type, info->cshw_blocks,
> > + BLK_MASK(info->cshw_blocks),
> > + offset);
> > + break;
> > + case DRM_PANTHOR_PERF_BLOCK_TILER:
> > + offset = PANTHOR_PERF_SET_BLOCK_DESC_DATA(desc, type, info->tiler_blocks,
> > + BLK_MASK(info->tiler_blocks),
> > + offset);
> > + break;
> > + case DRM_PANTHOR_PERF_BLOCK_MEMSYS:
> > + offset = PANTHOR_PERF_SET_BLOCK_DESC_DATA(desc, type, info->memsys_blocks,
> > + BLK_MASK(info->memsys_blocks),
> > + offset);
> > + break;
> > + case DRM_PANTHOR_PERF_BLOCK_SHADER:
> > + offset = PANTHOR_PERF_SET_BLOCK_DESC_DATA(desc, type,
> > + get_reserved_sc_blocks(ptdev),
> > + get_sc_mask(ptdev), offset);
> > + break;
> > + case DRM_PANTHOR_PERF_BLOCK_MAX:
> > + drm_WARN_ON_ONCE(&ptdev->base,
> > + "DRM_PANTHOR_PERF_BLOCK_MAX should be unreachable!");
> > + break;
> > + }
> > + }
> > +
> > + /* Computed size is not the same as the reported size, so we should not proceed in
> > + * initializing the sampling session.
> > + */
> > + if (offset != fw_sample_size)
> > + return -EINVAL;
> > +
> > + desc->buffer_size = offset;
> > +
> > + return 0;
> > +}
> > +
> > +static int panthor_perf_fw_stop_sampling(struct panthor_device *ptdev)
> > +{
> > + struct panthor_fw_global_iface *glb_iface = panthor_fw_get_glb_iface(ptdev);
> > + u32 acked;
> > + int ret;
> > +
> > + if (~READ_ONCE(glb_iface->input->req) & GLB_PERFCNT_ENABLE)
> > + return 0;
> > +
> > + panthor_fw_update_reqs(glb_iface, req, 0, GLB_PERFCNT_ENABLE);
> > + gpu_write(ptdev, CSF_DOORBELL(CSF_GLB_DOORBELL_ID), 1);
> > + ret = panthor_fw_glb_wait_acks(ptdev, GLB_PERFCNT_ENABLE, &acked, 100);
> > + if (ret)
> > + drm_warn(&ptdev->base, "Could not disable performance counters");
> > +
> > + return ret;
> > +}
> > +
> > +static int panthor_perf_fw_start_sampling(struct panthor_device *ptdev)
> > +{
> > + struct panthor_fw_global_iface *glb_iface = panthor_fw_get_glb_iface(ptdev);
> > + u32 acked;
> > + int ret;
> > +
> > + if (READ_ONCE(glb_iface->input->req) & GLB_PERFCNT_ENABLE)
> > + return 0;
> > +
> > + /**
> > + * The spec mandates that the host zero the PRFCNT_EXTRACT register before an enable
> > + * operation, and each (re-)enable will require an enable-disable pair to program
> > + * the new changes onto the FW interface.
> > + */
> > + WRITE_ONCE(glb_iface->input->perfcnt_extract, 0);
> > +
> > + panthor_fw_update_reqs(glb_iface, req, GLB_PERFCNT_ENABLE, GLB_PERFCNT_ENABLE);
> > + gpu_write(ptdev, CSF_DOORBELL(CSF_GLB_DOORBELL_ID), 1);
> > + ret = panthor_fw_glb_wait_acks(ptdev, GLB_PERFCNT_ENABLE, &acked, 100);
> > + if (ret)
> > + drm_warn(&ptdev->base, "Could not enable performance counters");
> > +
> > + return ret;
> > +}
> > +
> > +static void panthor_perf_fw_write_sampler_config(struct panthor_perf_sampler *sampler)
> > +{
> > + struct panthor_fw_global_iface *glb_iface = panthor_fw_get_glb_iface(sampler->ptdev);
> > + const u32 counters = sampler->ptdev->perf_info.counters_per_block;
> > + const struct panthor_perf_enable_masks *const em = sampler->em;
> > + u32 perfcnt_config;
> > +
> > + glb_iface->input->perfcnt_csf_enable =
> > + compress_enable_mask(counters, em->mask[DRM_PANTHOR_PERF_BLOCK_CSHW]);
> > + glb_iface->input->perfcnt_shader_enable =
> > + compress_enable_mask(counters, em->mask[DRM_PANTHOR_PERF_BLOCK_SHADER]);
> > + glb_iface->input->perfcnt_mmu_l2_enable =
> > + compress_enable_mask(counters, em->mask[DRM_PANTHOR_PERF_BLOCK_MEMSYS]);
> > + glb_iface->input->perfcnt_tiler_enable =
> > + compress_enable_mask(counters, em->mask[DRM_PANTHOR_PERF_BLOCK_TILER]);
> > + glb_iface->input->perfcnt_fw_enable =
> > + compress_enable_mask(counters, em->mask[DRM_PANTHOR_PERF_BLOCK_FW]);
> > + glb_iface->input->perfcnt_csg_enable = 0;
> > +
> > + WRITE_ONCE(glb_iface->input->perfcnt_as, panthor_vm_as(panthor_fw_vm(sampler->ptdev)));
> > + WRITE_ONCE(glb_iface->input->perfcnt_base, panthor_kernel_bo_gpuva(sampler->rb));
> > +
> > + perfcnt_config = GLB_PERFCNT_CONFIG_SIZE(perf_ringbuf_slots);
> > + perfcnt_config |= GLB_PERFCNT_CONFIG_SET(sampler->set_config);
> > + if (sampler->ptdev->perf_info.flags & DRM_PANTHOR_PERF_BLOCK_STATES_SUPPORT)
> > + perfcnt_config |= GLB_PERFCNT_METADATA_ENABLE;
> > +
> > + WRITE_ONCE(glb_iface->input->perfcnt_config, perfcnt_config);
> > +}
> > +
> > +static void session_populate_sample_header(struct panthor_perf_session *session,
> > + struct drm_panthor_perf_sample_header *hdr, u8 set)
> > +{
> > + *hdr = (struct drm_panthor_perf_sample_header) {
> > + .block_set = set,
> > + .user_data = session->user_data,
> > + .timestamp_start_ns = session->sample_start_ns,
> > + /**
> > + * TODO This should be changed to use the GPU clocks and the TIMESTAMP register,
> > + * when support is added.
> > + */
> > + .timestamp_end_ns = ktime_get_raw_ns(),
> > + };
> > +}
> > +
> > +/**
> > + * session_accumulate_sample - Accumulate the counters that are requested by the session
> > + * into the target buffer.
> > + *
> > + * @ptdev: Panthor device
> > + * @session: Perf session
> > + * @session_sample: Starting offset of the sample in the userspace mapping.
> > + * @sampler_sample: Starting offset of the sample in the sampler intermediate buffer.
> > + *
> > + * The hardware supports counter selection at the granularity of 1 bit per 4 counters, and there
> > + * is a single global FW frontend to program the counter requests from multiple sessions. This may
> > + * lead to a large disparity between the requested and provided counters for an individual client.
> > + * To remove this cross-talk, we patch out the counters that have not been requested by this
> > + * session and update the PRFCNT_EN, the header counter containing a bitmask of enabled counters,
> > + * accordingly.
> > + */
> > +static void session_accumulate_sample(struct panthor_device *ptdev,
> > + struct panthor_perf_session *session,
> > + u8 *session_sample, u8 *sampler_sample)
> > +{
> > + const struct drm_panthor_perf_info *const perf_info = &ptdev->perf_info;
> > + const u32 counters = perf_info->counters_per_block;
> > + const size_t block_size = get_annotated_block_size(perf_info->counters_per_block);
> > + const size_t sample_size = perf_info->sample_size;
> > + const size_t sample_header_size = perf_info->sample_header_size;
> > + const size_t data_size = sample_size - sample_header_size;
> > + struct drm_panthor_perf_sample_header *hdr = (typeof(hdr))session_sample;
> > +
> > + hdr->timestamp_end_ns = ktime_get_raw_ns();
> > +
> > + session_sample += sample_header_size;
> > + sampler_sample += sample_header_size;
> > +
> > + for (size_t i = 0; i < data_size; i += block_size) {
> > + DECLARE_BITMAP(enabled_ctrs, PANTHOR_PERF_EM_BITS);
> > + struct panthor_perf_counter_block *dst_blk = (typeof(dst_blk))(session_sample + i);
> > + struct panthor_perf_counter_block *src_blk = (typeof(src_blk))(sampler_sample + i);
> > +
> > + bitmap_from_arr64(enabled_ctrs, dst_blk->header.enable_mask, PANTHOR_PERF_EM_BITS);
> > + bitmap_clear(enabled_ctrs, 0, PANTHOR_HEADER_COUNTERS);
> > +
> > + dst_blk->counters[PANTHOR_CTR_TIMESTAMP_HI] =
> > + src_blk->counters[PANTHOR_CTR_TIMESTAMP_HI];
> > + dst_blk->counters[PANTHOR_CTR_TIMESTAMP_LO] =
> > + src_blk->counters[PANTHOR_CTR_TIMESTAMP_LO];
> > +
> > + for (size_t ctr_idx = PANTHOR_HEADER_COUNTERS; ctr_idx < counters; ctr_idx++)
> > + if (test_bit(ctr_idx, enabled_ctrs))
> > + dst_blk->counters[ctr_idx] += src_blk->counters[ctr_idx];
> > + }
> > +
> > + hdr->timestamp_end_ns = ktime_get_raw_ns();
> > + hdr->user_data = session->user_data;
> > +}
> > +
> > +static void panthor_perf_fw_request_sample(struct panthor_perf_sampler *sampler)
> > +{
> > + struct panthor_fw_global_iface *glb_iface = panthor_fw_get_glb_iface(sampler->ptdev);
> > +
> > + panthor_fw_toggle_reqs(glb_iface, req, ack, GLB_PERFCNT_SAMPLE);
> > + gpu_write(sampler->ptdev, CSF_DOORBELL(CSF_GLB_DOORBELL_ID), 1);
> > +}
> > +
> > +/**
> > + * session_populate_sample - Write out a new sample into a previously populated slot in the user
> > + * ringbuffer and update both the header of the block and the PRFCNT_EN
> > + * counter to contain only the selected subset of counters for that block.
> > + *
> > + * @ptdev: Panthor device
> > + * @session: Perf session
> > + * @session_sample: Pointer aligned to the start of the data section of the sample in the targeted
> > + * slot.
> > + * @sampler_sample: Pointer aligned to the start of the data section of the intermediate sampler
> > + * buffer.
> > + *
> > + * When a new sample slot is targeted, it must be cleared of the data already existing there,
> > + * enabling a direct copy from the intermediate buffer and then zeroing out any counters
> > + * that are not required for the current session.
> > + */
> > +static void session_populate_sample(struct panthor_device *ptdev,
> > + struct panthor_perf_session *session, u8 *session_sample,
> > + u8 *sampler_sample)
> > +{
> > + const struct drm_panthor_perf_info *const perf_info = &ptdev->perf_info;
> > +
> > + const size_t block_size = get_annotated_block_size(perf_info->counters_per_block);
> > + const size_t sample_size = session_get_user_sample_size(perf_info);
> > + const size_t sample_header_size = perf_info->sample_header_size;
> > + const size_t data_size = sample_size - sample_header_size;
> > + const u32 counters = perf_info->counters_per_block;
> > +
> > + session_populate_sample_header(session,
> > + (struct drm_panthor_perf_sample_header *)session_sample,
> > + ptdev->perf->sampler.set_config);
> > +
> > + session_sample += sample_header_size;
> > +
> > + memcpy(session_sample, sampler_sample + sample_header_size, data_size);
> > +
> > + for (size_t i = 0; i < data_size; i += block_size) {
> > + DECLARE_BITMAP(em_diff, PANTHOR_PERF_EM_BITS);
> > + struct panthor_perf_counter_block *blk = (typeof(blk))(session_sample + i);
> > + enum drm_panthor_perf_block_type type = blk->header.block_type;
> > + unsigned long *blk_em = session->enabled_counters->mask[type];
> > +
> > + bitmap_from_arr64(em_diff, blk->header.enable_mask, PANTHOR_PERF_EM_BITS);
> > +
> > + bitmap_andnot(em_diff, em_diff, blk_em, PANTHOR_PERF_EM_BITS);
> > + bitmap_clear(em_diff, 0, PANTHOR_HEADER_COUNTERS);
> > +
> > + blk->counters[PANTHOR_CTR_PRFCNT_EN] = compress_enable_mask(counters, blk_em);
> > +
> > + for (size_t ctr_idx = PANTHOR_HEADER_COUNTERS; ctr_idx < counters; ctr_idx++) {
> > + if (test_bit(ctr_idx, em_diff))
> > + blk->counters[ctr_idx] = 0;
> > + }
> > +
> > + bitmap_to_arr64(&blk->header.enable_mask, blk_em, PANTHOR_PERF_EM_BITS);
> > + }
> > +}
> > +
> > +static int session_copy_sample(struct panthor_device *ptdev, struct panthor_perf_session *session)
> > +{
> > + struct panthor_perf *perf = ptdev->perf;
> > + const size_t sample_size = session_get_user_sample_size(&ptdev->perf_info);
> > + const u64 insert_idx = session_read_insert_idx(session);
> > + const u64 extract_idx = session_read_extract_idx(session);
> > + u8 *new_sample;
> > +
> > + if (!CIRC_SPACE(insert_idx, extract_idx, session->ringbuf_slots))
> > + return -ENOSPC;
> > +
> > + if (READ_ONCE(session->pending_sample_request) == SAMPLE_TYPE_INITIAL)
> > + return 0;
> > +
> > + new_sample = session->samples + insert_idx * sample_size;
> > +
> > + if (session->accum_idx != insert_idx) {
> > + session_populate_sample(ptdev, session, new_sample, perf->sampler.sample);
> > + session->accum_idx = insert_idx;
> > + } else {
> > + session_accumulate_sample(ptdev, session, new_sample, perf->sampler.sample);
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static void session_emit_sample(struct panthor_perf_session *session)
> > +{
> > + const u64 insert_idx = session_read_insert_idx(session);
> > + const enum session_sample_type type = READ_ONCE(session->pending_sample_request);
> > +
> > + if (type == SAMPLE_TYPE_INITIAL || type == SAMPLE_TYPE_NONE)
> > + goto reset_sample_request;
> > +
> > + session_write_insert_idx(session, (insert_idx + 1) % session->ringbuf_slots);
> > +
> > + /* Since we are about to notify userspace, we must ensure that all changes to memory
> > + * are visible.
> > + */
> > + wmb();
> > +
> > + eventfd_signal(session->eventfd);
> > +
> > +reset_sample_request:
> > + WRITE_ONCE(session->pending_sample_request, SAMPLE_TYPE_NONE);
> > +}
> > +
> > +#define PRFCNT_IRQS (GLB_PERFCNT_OVERFLOW | GLB_PERFCNT_SAMPLE | GLB_PERFCNT_THRESHOLD)
> > +
> > +void panthor_perf_report_irq(struct panthor_device *ptdev, u32 status)
> > +{
> > + struct panthor_perf *const perf = ptdev->perf;
> > + struct panthor_perf_sampler *sampler;
> > + struct panthor_fw_global_iface *glb_iface = panthor_fw_get_glb_iface(ptdev);
> > + bool sample_requested;
> > +
> > + if (!(status & JOB_INT_GLOBAL_IF))
> > + return;
> > +
> > + if (!perf)
> > + return;
> > +
> > + sampler = &perf->sampler;
> > +
> > + const u32 ack = READ_ONCE(glb_iface->output->ack);
> > + const u32 req = READ_ONCE(glb_iface->input->req);
> > +
> > + scoped_guard(spinlock_irqsave, &sampler->pend_lock)
> > + sample_requested = sampler->sample_requested;
> > +
> > + /*
> > + * TODO Fix up the error handling for overflow. Currently, the user is unblocked
> > + * with a completely empty sample, whic is not the intended behaviour.
> > + */
> > + if (drm_WARN_ON_ONCE(&ptdev->base, (req ^ ack) & GLB_PERFCNT_OVERFLOW))
> > + goto emit;
> > +
> > + if ((sample_requested && (req & GLB_PERFCNT_SAMPLE) == (ack & GLB_PERFCNT_SAMPLE)) ||
> > + ((req ^ ack) & GLB_PERFCNT_THRESHOLD)) {
> > + const u32 extract_idx = READ_ONCE(glb_iface->input->perfcnt_extract);
> > + const u32 insert_idx = READ_ONCE(glb_iface->output->perfcnt_insert);
> > +
> > + /* If the sample was requested around a reset, some time may be needed
> > + * for the FW interface to be updated, so we reschedule a sample
> > + * and return immediately.
> > + */
> > + if (insert_idx == extract_idx) {
> > + guard(spinlock_irqsave)(&sampler->pend_lock);
> > + if (sampler->sample_requested)
> > + panthor_perf_fw_request_sample(sampler);
> > +
> > + return;
> > + }
> > +
> > + WRITE_ONCE(glb_iface->input->perfcnt_extract,
> > + panthor_perf_handle_sample(ptdev, extract_idx, insert_idx));
> > + }
> > +
> > + scoped_guard(mutex, &sampler->sampler_lock)
> > + {
> > + struct list_head *pos;
> > +
> > + list_for_each(pos, &sampler->session_list) {
> > + struct panthor_perf_session *session = list_entry(pos,
> > + struct panthor_perf_session, sessions);
> > +
> > + session_copy_sample(ptdev, session);
> > + }
> > + }
> > +
> > +emit:
> > + scoped_guard(spinlock_irqsave, &sampler->pend_lock) {
> > + struct list_head *pos, *tmp;
> > +
> > + list_for_each_safe(pos, tmp, &sampler->pending_samples) {
> > + struct panthor_perf_session *session = list_entry(pos,
> > + struct panthor_perf_session, pending);
> > +
> > + session_emit_sample(session);
> > + list_del(pos);
> > + session_put(session);
> > + }
> > +
> > + sampler->sample_requested = false;
> > + }
> > +
> > + memset(sampler->sample, 0, session_get_user_sample_size(&ptdev->perf_info));
> > + complete(&sampler->sample_handled);
> > +}
> > +
> > +static int panthor_perf_sampler_init(struct panthor_perf_sampler *sampler,
> > + struct panthor_device *ptdev)
> > +{
> > + struct panthor_kernel_bo *bo;
> > + u8 *sample;
> > + int ret;
> > +
> > + ret = panthor_perf_setup_fw_buffer_desc(ptdev, sampler);
> > + if (ret) {
> > + drm_err(&ptdev->base,
> > + "Failed to setup descriptor for FW ring buffer, err = %d", ret);
> > + return ret;
> > + }
> > +
> > + bo = panthor_kernel_bo_create(ptdev, panthor_fw_vm(ptdev),
> > + sampler->desc.buffer_size * perf_ringbuf_slots,
> > + DRM_PANTHOR_BO_NO_MMAP,
> > + DRM_PANTHOR_VM_BIND_OP_MAP_NOEXEC |
> > + DRM_PANTHOR_VM_BIND_OP_MAP_UNCACHED,
> > + PANTHOR_VM_KERNEL_AUTO_VA,
> > + "perf_ringbuf");
> > +
> > + if (IS_ERR_OR_NULL(bo))
> > + return IS_ERR(bo) ? PTR_ERR(bo) : -ENOMEM;
> > +
> > + ret = panthor_kernel_bo_vmap(bo);
> > + if (ret)
> > + goto cleanup_bo;
> > +
> > + sample = kzalloc(session_get_user_sample_size(&ptdev->perf_info), GFP_KERNEL);
> > + if (ZERO_OR_NULL_PTR(sample)) {
> > + ret = -ENOMEM;
> > + goto cleanup_vmap;
> > + }
> > +
> > + sampler->rb = bo;
> > + sampler->sample = sample;
> > + sampler->sample_slots = perf_ringbuf_slots;
> > + sampler->em = kzalloc(sizeof(*sampler->em), GFP_KERNEL);
>
> I guess you're not checking kzalloc's return value because
> struct panthor_perf_enable_masks isn't too big either, but in that case
> you might as well embed it in the sampler struct straight away.
>
> > + mutex_init(&sampler->sampler_lock);
> > + spin_lock_init(&sampler->pend_lock);
> > + INIT_LIST_HEAD(&sampler->session_list);
> > + INIT_LIST_HEAD(&sampler->pending_samples);
> > + init_completion(&sampler->sample_handled);
> > +
> > + sampler->ptdev = ptdev;
> > +
> > + return 0;
> > +
> > +cleanup_vmap:
> > + panthor_kernel_bo_vunmap(bo);
> > +
> > +cleanup_bo:
> > + panthor_kernel_bo_destroy(bo);
> > +
> > + return ret;
> > +}
> > +
> > +static void panthor_perf_sampler_term(struct panthor_perf_sampler *sampler)
> > +{
> > + int ret;
> > + bool requested;
> > +
> > + scoped_guard(spinlock_irqsave, &sampler->pend_lock)
> > + requested = sampler->sample_requested;
> > +
> > + if (requested)
> > + wait_for_completion_killable(&sampler->sample_handled);
> > +
> > + ret = panthor_perf_fw_stop_sampling(sampler->ptdev);
> > + if (ret)
> > + drm_warn_once(&sampler->ptdev->base, "Sampler termination failed, ret = %d", ret);
> > +
> > + /* At this point, the sampler enable mask is already zero, so it can be used directly. */
> > + panthor_perf_fw_write_sampler_config(sampler);
> > +
> > + kfree(sampler->em);
> > + kfree(sampler->sample);
> > +
> > + panthor_kernel_bo_destroy(sampler->rb);
> > +}
> > +
> > +static int panthor_perf_sampler_add(struct panthor_perf_sampler *sampler,
> > + struct panthor_perf_session *session, u8 set)
> > +{
> > + int ret = 0;
> > + struct panthor_perf_enable_masks *const session_em = session->enabled_counters;
> > +
> > + guard(mutex)(&sampler->sampler_lock);
> > +
> > + /* Early check for whether a new set can be configured. */
> > + if (!atomic_read(&sampler->enabled_clients))
> > + sampler->set_config = set;
> > + else
> > + if (sampler->set_config != set)
> > + return -EBUSY;
> > +
> > + panthor_perf_em_add(sampler->em, session_em);
> > + ret = pm_runtime_resume_and_get(sampler->ptdev->base.dev);
> > + if (ret)
> > + return ret;
> > +
> > + if (atomic_read(&sampler->enabled_clients)) {
> > + ret = panthor_perf_fw_stop_sampling(sampler->ptdev);
> > + if (ret)
> > + return ret;
> > + }
> > +
> > + panthor_perf_fw_write_sampler_config(sampler);
> > +
> > + ret = panthor_perf_fw_start_sampling(sampler->ptdev);
> > + if (ret)
> > + return ret;
> > +
> > + session_get(session);
> > + list_add_tail(&session->sessions, &sampler->session_list);
> > + atomic_inc(&sampler->enabled_clients);
> > +
> > + return 0;
> > +}
> > +
> > +static int panthor_perf_sampler_remove_session(struct panthor_perf_sampler *sampler,
> > + struct panthor_perf_session *session)
> > +{
> > + int ret;
> > + struct list_head *snode;
> > +
> > + guard(mutex)(&sampler->sampler_lock);
> > +
> > + list_del_init(&session->sessions);
> > + session_put(session);
> > +
> > + panthor_perf_em_zero(sampler->em);
> > + list_for_each(snode, &sampler->session_list)
> > + {
> > + struct panthor_perf_session *session =
> > + container_of(snode, typeof(*session), sessions);
> > +
> > + panthor_perf_em_add(sampler->em, session->enabled_counters);
> > + }
> > +
> > + ret = panthor_perf_fw_stop_sampling(sampler->ptdev);
> > + if (ret)
> > + return ret;
> > +
> > + atomic_dec(&sampler->enabled_clients);
> > + pm_runtime_put_sync(sampler->ptdev->base.dev);
> > +
> > + panthor_perf_fw_write_sampler_config(sampler);
> > +
> > + if (atomic_read(&sampler->enabled_clients))
> > + return panthor_perf_fw_start_sampling(sampler->ptdev);
> > + return 0;
> > +}
> > +
> > /**
> > * panthor_perf_init - Initialize the performance counter subsystem.
> > * @ptdev: Panthor device
> > @@ -382,6 +1348,10 @@ int panthor_perf_init(struct panthor_device *ptdev)
> > .max = 1,
> > };
> >
> > + ret = panthor_perf_sampler_init(&perf->sampler, ptdev);
> > + if (ret)
> > + return ret;
> > +
> > drm_info(&ptdev->base, "Performance counter subsystem initialized");
> >
> > ptdev->perf = no_free_ptr(perf);
> > @@ -389,6 +1359,70 @@ int panthor_perf_init(struct panthor_device *ptdev)
> > return ret;
> > }
> >
> > +static int sampler_request(struct panthor_perf_sampler *sampler,
> > + struct panthor_perf_session *session, enum session_sample_type type)
> > +{
> > + /*
> > + * If a previous sample has not been handled yet, the session cannot request another
> > + * sample. If this happens too often, the requested sample rate is too high.
> > + */
> > + if (READ_ONCE(session->pending_sample_request) != SAMPLE_TYPE_NONE)
> > + return -EBUSY;
> > +
> > + WRITE_ONCE(session->pending_sample_request, type);
> > + session_get(session);
> > +
> > + scoped_guard(spinlock_irqsave, &sampler->pend_lock) {
> > + list_add_tail(&session->pending, &sampler->pending_samples);
> > +
> > + if (!sampler->sample_requested) {
> > + reinit_completion(&sampler->sample_handled);
> > + sampler->sample_requested = true;
> > + panthor_perf_fw_request_sample(sampler);
> > + }
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +/**
> > + * panthor_perf_sampler_request_initial - Request an initial sample.
> > + * @sampler: Panthor sampler
> > + * @session: Target session
> > + *
> > + * Perform a synchronous sample that gets immediately discarded. This sets a baseline at the point
> > + * of time a new session is started, to avoid having counters from before the session.
> > + */
> > +static int panthor_perf_sampler_request_initial(struct panthor_perf_sampler *sampler,
> > + struct panthor_perf_session *session)
> > +{
> > + int ret = sampler_request(sampler, session, SAMPLE_TYPE_INITIAL);
> > +
> > + if (ret)
> > + return ret;
> > +
> > + return wait_for_completion_timeout(&sampler->sample_handled,
> > + msecs_to_jiffies(1000));
Here you want to return 0 on success, but wait_for_completion_timeout() returns at least 1 when
completed without timing out, so we need to negate the whole statement before returning.
> > +}
> > +
> > +/**
> > + * panthor_perf_sampler_request_sample - Request a counter sample for the userspace client.
> > + * @sampler: Panthor sampler
> > + * @session: Target session
> > + *
> > + * A session that has already requested a sample cannot request another one until the previous
> > + * sample has been delivered.
> > + *
> > + * Return:
> > + * * %0 - The sample has been requested successfully.
> > + * * %-EBUSY - The target session has already requested a sample and has not received it yet.
> > + */
> > +static int panthor_perf_sampler_request_sample(struct panthor_perf_sampler *sampler,
> > + struct panthor_perf_session *session)
> > +{
> > + return sampler_request(sampler, session, SAMPLE_TYPE_REGULAR);
> > +}
> > +
> > static int session_validate_set(u8 set)
> > {
> > if (set > DRM_PANTHOR_PERF_SET_TERTIARY)
> > @@ -513,6 +1547,10 @@ int panthor_perf_session_setup(struct drm_file *file, struct panthor_perf *perf,
> > kref_init(&session->ref);
> > session->enabled_counters = em;
> >
> > + ret = panthor_perf_sampler_add(&perf->sampler, session, setup_args->block_set);
> > + if (ret)
> > + goto cleanup_xa_alloc;
> > +
> > session->sample_freq_ns = setup_args->sample_freq_ns;
> > session->user_sample_size = user_sample_size;
> > session->ring_buf = ringbuffer;
> > @@ -523,6 +1561,9 @@ int panthor_perf_session_setup(struct drm_file *file, struct panthor_perf *perf,
> >
> > return session_id;
> >
> > +cleanup_xa_alloc:
> > + xa_store(&perf->sessions, session_id, NULL, GFP_KERNEL);
> > +
> > cleanup_em:
> > kfree(em);
> >
> > @@ -550,6 +1591,8 @@ int panthor_perf_session_setup(struct drm_file *file, struct panthor_perf *perf,
> > static int session_stop(struct panthor_perf *perf, struct panthor_perf_session *session,
> > u64 user_data)
> > {
> > + int ret;
> > +
> > if (!test_bit(PANTHOR_PERF_SESSION_ACTIVE, session->state))
> > return 0;
> >
> > @@ -562,9 +1605,12 @@ static int session_stop(struct panthor_perf *perf, struct panthor_perf_session *
> >
> > session->user_data = user_data;
> >
> > + ret = panthor_perf_sampler_request_sample(&perf->sampler, session);
> > + if (ret)
> > + return ret;
> > +
> > clear_bit(PANTHOR_PERF_SESSION_ACTIVE, session->state);
> >
> > - /* TODO Calls to the FW interface will go here in later patches. */
> > return 0;
> > }
> >
> > @@ -583,8 +1629,7 @@ static int session_start(struct panthor_perf *perf, struct panthor_perf_session
> > if (session->sample_freq_ns)
> > session->user_data = user_data;
> >
> > - /* TODO Calls to the FW interface will go here in later patches. */
> > - return 0;
> > + return panthor_perf_sampler_request_initial(&perf->sampler, session);
> > }
> >
> > static int session_sample(struct panthor_perf *perf, struct panthor_perf_session *session,
> > @@ -605,20 +1650,22 @@ static int session_sample(struct panthor_perf *perf, struct panthor_perf_session
> > * the current sample, and one for a stop sample, since a stop command should
> > * always be acknowledged by taking a final sample and stopping the session.
> > */
> > - if (CIRC_SPACE_TO_END(insert_idx, extract_idx, session->ringbuf_slots) < 2)
> > + if (CIRC_SPACE(insert_idx, extract_idx, session->ringbuf_slots) < 2)
> > return -EBUSY;
> >
> > session->sample_start_ns = ktime_get_raw_ns();
> > session->user_data = user_data;
> >
> > - return 0;
> > + return panthor_perf_sampler_request_sample(&perf->sampler, session);
> > }
> >
> > static int session_destroy(struct panthor_perf *perf, struct panthor_perf_session *session)
> > {
> > + int ret = panthor_perf_sampler_remove_session(&perf->sampler, session);
> > +
> > session_put(session);
> >
> > - return 0;
> > + return ret;
> > }
> >
> > static int session_teardown(struct panthor_perf *perf, struct panthor_perf_session *session)
> > @@ -825,6 +1872,8 @@ void panthor_perf_unplug(struct panthor_device *ptdev)
> >
> > xa_destroy(&perf->sessions);
> >
> > + panthor_perf_sampler_term(&perf->sampler);
> > +
> > kfree(ptdev->perf);
> >
> > ptdev->perf = NULL;
> > diff --git a/drivers/gpu/drm/panthor/panthor_perf.h b/drivers/gpu/drm/panthor/panthor_perf.h
> > index c46f94ed8a96..5a14854368eb 100644
> > --- a/drivers/gpu/drm/panthor/panthor_perf.h
> > +++ b/drivers/gpu/drm/panthor/panthor_perf.h
> > @@ -28,5 +28,7 @@ int panthor_perf_session_sample(struct panthor_file *pfile, struct panthor_perf
> > u32 sid, u64 user_data);
> > void panthor_perf_session_destroy(struct panthor_file *pfile, struct panthor_perf *perf);
> >
> > +void panthor_perf_report_irq(struct panthor_device *ptdev, u32 status);
> > +
> > #endif /* __PANTHOR_PERF_H__ */
> >
> > --
> > 2.33.0.dirty
Adrian Larumbe
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