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Message-ID: <e204adc8-3683-4bee-b4c1-6e14ff27e802@arm.com>
Date: Mon, 7 Apr 2025 09:32:05 +0100
From: Lukas Zapolskas <lukas.zapolskas@....com>
To: 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>,
dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Cc: Adrián Larumbe <adrian.larumbe@...labora.com>
Subject: Re: [PATCH v3 5/7] drm/panthor: Implement the counter sampler and
sample handling
On 01/04/2025 16:48, 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 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 | 1066 +++++++++++++++++++++++-
> drivers/gpu/drm/panthor/panthor_perf.h | 2 +
> 4 files changed, 1059 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/gpu/drm/panthor/panthor_fw.c b/drivers/gpu/drm/panthor/panthor_fw.c
> index 0f52766a3120..e3948354daa4 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"
>
> @@ -987,9 +988,12 @@ 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;
>
> @@ -1018,6 +1022,8 @@ 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 62c27be4ca8b..3cb79b999886 100644
> --- a/drivers/gpu/drm/panthor/panthor_perf.c
> +++ b/drivers/gpu/drm/panthor/panthor_perf.c
> @@ -9,7 +9,11 @@
>
> #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"
>
> /**
> * PANTHOR_PERF_EM_BITS - Number of bits in a user-facing enable mask. This must correspond
> @@ -18,6 +22,81 @@
> */
> #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,
> @@ -63,6 +142,122 @@ 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 {
> + /**
> + * @last_ack: Temporarily storing the last GLB_ACK status. Without storing this data,
> + * we do not know whether a toggle bit has been handled.
> + */
> + u32 last_ack;
> +
> + /**
> + * @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);
>
> @@ -184,6 +379,9 @@ struct panthor_perf {
> * @sessions: Global map of sessions, accessed by their ID.
> */
> struct xarray sessions;
> +
> + /** @sampler: FW control interface. */
> + struct panthor_perf_sampler sampler;
> };
>
> /**
> @@ -216,7 +414,7 @@ static void panthor_perf_info_init(struct panthor_device *ptdev)
> }
>
> static struct panthor_perf_enable_masks *panthor_perf_create_em(struct drm_panthor_perf_cmd_setup
> - *setup_args)
> + *setup_args)
> {
> struct panthor_perf_enable_masks *em = kmalloc(sizeof(*em), GFP_KERNEL);
> if (IS_ERR_OR_NULL(em))
> @@ -236,6 +434,23 @@ 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 *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 size_t get_annotated_block_size(size_t counters_per_block)
> {
> return struct_size_t(struct panthor_perf_counter_block, counters, counters_per_block);
> @@ -249,6 +464,12 @@ static u64 session_read_extract_idx(struct panthor_perf_session *session)
> return smp_load_acquire(&session->control->extract_idx);
> }
>
> +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)
> {
> return session->control->insert_idx;
> @@ -301,7 +522,7 @@ static void session_put(struct panthor_perf_session *session)
> * Return: valid session pointer or an ERR_PTR.
> */
> static struct panthor_perf_session *session_find(struct panthor_file *pfile,
> - struct panthor_perf *perf, u32 sid)
> + struct panthor_perf *perf, u32 sid)
> {
> struct panthor_perf_session *session;
>
> @@ -327,6 +548,738 @@ static struct panthor_perf_session *session_find(struct panthor_file *pfile,
> return session;
> }
>
> +static u32 compress_enable_mask(unsigned long *const src)
> +{
> + size_t i;
> + u32 result = 0;
> + unsigned long clump;
> +
> + for_each_set_clump8(i, clump, src, PANTHOR_PERF_EM_BITS) {
> + const unsigned long shift = div_u64(i, 4);
> +
> + result |= !!(clump & GENMASK(3, 0)) << shift;
> + result |= !!(clump & GENMASK(7, 4)) << (shift + 1);
> + }
> +
> + return result;
> +}
> +
> +static void expand_enable_mask(u32 em, unsigned long *const dst)
> +{
> + size_t i;
> + 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 * 4, 4);
> +}
> +
> +/**
> + * 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 *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 size_t session_get_user_sample_size(const struct drm_panthor_perf_info *const info)
> +{
> + const size_t block_size = get_annotated_block_size(info->counters_per_block);
> + const size_t block_nr = info->cshw_blocks + info->fw_blocks +
> + info->tiler_blocks + info->memsys_blocks + info->shader_blocks;
> +
> + return sizeof(struct drm_panthor_perf_sample_header) + (block_size * block_nr);
> +}
> +
> +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 = (i + 1) % sampler->sample_slots) {
> + u8 *fw_sample = (u8 *)sampler->rb->kmap + i * sampler->desc.buffer_size;
> +
> + for (size_t fw_off = 0, ann_off = sizeof(struct drm_panthor_perf_sample_header);
> + 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(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_shader_core_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_shader_core_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_shader_core_blocks(ptdev),
> + get_shader_core_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;
> +
> + 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_config(struct panthor_perf_sampler *sampler,
> + struct panthor_perf_enable_masks *em)
> +{
> + struct panthor_fw_global_iface *glb_iface = panthor_fw_get_glb_iface(sampler->ptdev);
> + u32 perfcnt_config;
> +
> + glb_iface->input->perfcnt_csf_enable =
> + compress_enable_mask(em->mask[DRM_PANTHOR_PERF_BLOCK_CSHW]);
> + glb_iface->input->perfcnt_shader_enable =
> + compress_enable_mask(em->mask[DRM_PANTHOR_PERF_BLOCK_SHADER]);
> + glb_iface->input->perfcnt_mmu_l2_enable =
> + compress_enable_mask(em->mask[DRM_PANTHOR_PERF_BLOCK_MEMSYS]);
> + glb_iface->input->perfcnt_tiler_enable =
> + compress_enable_mask(em->mask[DRM_PANTHOR_PERF_BLOCK_TILER]);
> + glb_iface->input->perfcnt_fw_enable =
> + compress_enable_mask(em->mask[DRM_PANTHOR_PERF_BLOCK_FW]);
> +
> + 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);
> +
> + /**
> + * 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);
> +}
> +
> +static void panthor_perf_fw_write_sampler_config(struct panthor_perf_sampler *sampler)
> +{
> + panthor_perf_fw_write_config(sampler, sampler->em);
> +}
> +
> +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 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 = sizeof(struct drm_panthor_perf_sample_header);
> + 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;
> +
> + for (size_t i = 0; i < data_size; i += block_size) {
> + size_t ctr_idx;
> + 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, 4);
> +
> + 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_each_set_bit(ctr_idx, enabled_ctrs, PANTHOR_PERF_EM_BITS)
> + dst_blk->counters[ctr_idx] += src_blk->counters[ctr_idx];
> + }
> +}
> +
> +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 = sizeof(struct drm_panthor_perf_sample_header);
> + const size_t data_size = sample_size - sample_header_size;
> +
> + memcpy(session_sample, sampler_sample, sample_size);
> +
> + session_populate_sample_header(session,
> + (struct drm_panthor_perf_sample_header *)session_sample,
> + ptdev->perf->sampler.set_config);
> +
> + session_sample += sample_header_size;
> +
> + for (size_t i = 0; i < data_size; i += block_size) {
> + size_t ctr_idx;
> + 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, 4);
> +
> + blk->counters[PANTHOR_CTR_PRFCNT_EN] = compress_enable_mask(blk_em);
> +
> + for_each_set_bit(ctr_idx, em_diff, PANTHOR_PERF_EM_BITS)
> + 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 u32 insert_idx = session_read_insert_idx(session);
> + const u32 extract_idx = session_read_extract_idx(session);
> + u8 *new_sample;
> +
> + if (!CIRC_SPACE_TO_END(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);
> + else
> + session_accumulate_sample(ptdev, session, new_sample, perf->sampler.sample);
> +
> + return 0;
> +}
> +
> +static void session_emit_sample(struct panthor_perf_session *session)
> +{
> + const u32 insert_idx = session_read_insert_idx(session);
Since the ring buffer controls must be mapped read/write, we cannot
trust this value to be correctly wrapped. I will need to publish
a v4 with a fix for this and the addition of the sample size in
the DEV_QUERY uAPI.
> + 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->accum_idx = insert_idx;
> + 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);
> +
> + if (!(status & JOB_INT_GLOBAL_IF))
> + return;
> +
> + if (!perf)
> + return;
> +
> + sampler = &perf->sampler;
> +
> + /* TODO This needs locking. */
> + const u32 ack = READ_ONCE(glb_iface->output->ack);
> + const u32 fw_events = sampler->last_ack ^ ack;
> +
> + sampler->last_ack = ack;
> +
> + if (!(fw_events & PRFCNT_IRQS))
> + return;
> +
> + /* TODO Fix up the error handling for overflow. */
> + if (drm_WARN_ON_ONCE(&ptdev->base, fw_events & GLB_PERFCNT_OVERFLOW))
> + return;
> +
> + if (fw_events & (GLB_PERFCNT_SAMPLE | 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);
> +
> + 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);
> + }
> + }
> +
> + 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);
> + }
> + }
> +
> + memset(sampler->sample, 0, session_get_user_sample_size(&ptdev->perf_info));
> + sampler->sample_requested = false;
> + 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);
> +
> + 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);
> +
> + 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;
> +
> + if (sampler->sample_requested)
> + wait_for_completion_killable(&sampler->sample_handled);
> +
> + panthor_perf_fw_write_config(sampler, &(struct panthor_perf_enable_masks){});
> +
> + ret = panthor_perf_fw_stop_sampling(sampler->ptdev);
> + if (ret)
> + drm_warn_once(&sampler->ptdev->base, "Sampler termination failed, ret = %d", ret);
> +
> + 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 *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
> @@ -357,6 +1310,10 @@ 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);
> @@ -364,13 +1321,67 @@ int panthor_perf_init(struct panthor_device *ptdev)
> return ret;
> }
>
> -static size_t session_get_user_sample_size(const struct drm_panthor_perf_info *const info)
> +static int sampler_request(struct panthor_perf_sampler *sampler,
> + struct panthor_perf_session *session, enum session_sample_type type)
> {
> - const size_t block_size = get_annotated_block_size(info->counters_per_block);
> - const size_t block_nr = info->cshw_blocks + info->fw_blocks +
> - info->tiler_blocks + info->memsys_blocks + info->shader_blocks;
> + guard(spinlock_irqsave)(&sampler->pend_lock);
>
> - return sizeof(struct drm_panthor_perf_sample_header) + (block_size * block_nr);
> + /*
> + * 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);
> + 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));
> +}
> +
> +/**
> + * 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)
> @@ -401,8 +1412,8 @@ static int session_validate_set(u8 set)
> * Return: non-negative session identifier on success or negative error code on failure.
> */
> int panthor_perf_session_setup(struct panthor_device *ptdev, struct panthor_perf *perf,
> - struct drm_panthor_perf_cmd_setup *setup_args,
> - struct panthor_file *pfile)
> + struct drm_panthor_perf_cmd_setup *setup_args,
> + struct panthor_file *pfile)
> {
> struct panthor_perf_session *session;
> struct drm_gem_object *ringbuffer;
> @@ -494,6 +1505,10 @@ int panthor_perf_session_setup(struct panthor_device *ptdev, struct panthor_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;
> @@ -504,6 +1519,9 @@ int panthor_perf_session_setup(struct panthor_device *ptdev, struct panthor_perf
>
> return session_id;
>
> +cleanup_xa_alloc:
> + xa_store(&perf->sessions, session_id, NULL, GFP_KERNEL);
> +
> cleanup_em:
> kfree(em);
>
> @@ -529,8 +1547,10 @@ int panthor_perf_session_setup(struct panthor_device *ptdev, struct panthor_perf
> }
>
> static int session_stop(struct panthor_perf *perf, struct panthor_perf_session *session,
> - u64 user_data)
> + u64 user_data)
> {
> + int ret;
> +
> if (!test_bit(PANTHOR_PERF_SESSION_ACTIVE, session->state))
> return 0;
>
> @@ -543,14 +1563,17 @@ 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;
> }
>
> static int session_start(struct panthor_perf *perf, struct panthor_perf_session *session,
> - u64 user_data)
> + u64 user_data)
> {
> if (test_bit(PANTHOR_PERF_SESSION_ACTIVE, session->state))
> return 0;
> @@ -564,12 +1587,11 @@ 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,
> - u64 user_data)
> + u64 user_data)
> {
> if (!test_bit(PANTHOR_PERF_SESSION_ACTIVE, session->state))
> return 0;
> @@ -592,14 +1614,16 @@ static int session_sample(struct panthor_perf *perf, struct panthor_perf_session
> 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)
> @@ -675,7 +1699,7 @@ int panthor_perf_session_teardown(struct panthor_file *pfile, struct panthor_per
> * Return: 0 on success, negative error code on failure.
> */
> int panthor_perf_session_start(struct panthor_file *pfile, struct panthor_perf *perf,
> - u32 sid, u64 user_data)
> + u32 sid, u64 user_data)
> {
> struct panthor_perf_session *session = session_find(pfile, perf, sid);
> int err;
> @@ -708,7 +1732,7 @@ int panthor_perf_session_start(struct panthor_file *pfile, struct panthor_perf *
> * Return: 0 on success, negative error code on failure.
> */
> int panthor_perf_session_stop(struct panthor_file *pfile, struct panthor_perf *perf,
> - u32 sid, u64 user_data)
> + u32 sid, u64 user_data)
> {
> struct panthor_perf_session *session = session_find(pfile, perf, sid);
> int err;
> @@ -739,7 +1763,7 @@ int panthor_perf_session_stop(struct panthor_file *pfile, struct panthor_perf *p
> * Return: 0 on success, negative error code on failure.
> */
> int panthor_perf_session_sample(struct panthor_file *pfile, struct panthor_perf *perf,
> - u32 sid, u64 user_data)
> + u32 sid, u64 user_data)
> {
> struct panthor_perf_session *session = session_find(pfile, perf, sid);
> int err;
> @@ -806,6 +1830,8 @@ 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 89d61cd1f017..c482198b6fbd 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__ */
>
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