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Message-ID: <f973f656-acdf-320f-95d5-3f79cc3ce95a@linux.intel.com>
Date: Tue, 28 Mar 2023 14:57:33 +0100
From: Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com>
To: Rob Clark <robdclark@...il.com>, dri-devel@...ts.freedesktop.org
Cc: Rob Clark <robdclark@...omium.org>,
Pekka Paalanen <pekka.paalanen@...labora.com>,
Christian König <ckoenig.leichtzumerken@...il.com>,
intel-gfx@...ts.freedesktop.org,
open list <linux-kernel@...r.kernel.org>,
Sumit Semwal <sumit.semwal@...aro.org>,
"moderated list:DMA BUFFER SHARING FRAMEWORK"
<linaro-mm-sig@...ts.linaro.org>,
Luben Tuikov <luben.tuikov@....com>,
Rodrigo Vivi <rodrigo.vivi@...el.com>,
Gustavo Padovan <gustavo@...ovan.org>,
Matt Turner <mattst88@...il.com>,
freedreno@...ts.freedesktop.org,
Christian König <christian.koenig@....com>,
"open list:SYNC FILE FRAMEWORK" <linux-media@...r.kernel.org>
Subject: Re: [PATCH v10 07/15] dma-buf/sw_sync: Add fence deadline support
On 08/03/2023 15:52, Rob Clark wrote:
> From: Rob Clark <robdclark@...omium.org>
>
> This consists of simply storing the most recent deadline, and adding an
> ioctl to retrieve the deadline. This can be used in conjunction with
> the SET_DEADLINE ioctl on a fence fd for testing. Ie. create various
> sw_sync fences, merge them into a fence-array, set deadline on the
> fence-array and confirm that it is propagated properly to each fence.
>
> v2: Switch UABI to express deadline as u64
> v3: More verbose UAPI docs, show how to convert from timespec
> v4: Better comments, track the soonest deadline, as a normal fence
> implementation would, return an error if no deadline set.
>
> Signed-off-by: Rob Clark <robdclark@...omium.org>
> Reviewed-by: Christian König <christian.koenig@....com>
> Acked-by: Pekka Paalanen <pekka.paalanen@...labora.com>
> ---
> drivers/dma-buf/sw_sync.c | 81 ++++++++++++++++++++++++++++++++++++
> drivers/dma-buf/sync_debug.h | 2 +
> 2 files changed, 83 insertions(+)
>
> diff --git a/drivers/dma-buf/sw_sync.c b/drivers/dma-buf/sw_sync.c
> index 348b3a9170fa..f53071bca3af 100644
> --- a/drivers/dma-buf/sw_sync.c
> +++ b/drivers/dma-buf/sw_sync.c
> @@ -52,12 +52,33 @@ struct sw_sync_create_fence_data {
> __s32 fence; /* fd of new fence */
> };
>
> +/**
> + * struct sw_sync_get_deadline - get the deadline hint of a sw_sync fence
> + * @deadline_ns: absolute time of the deadline
> + * @pad: must be zero
> + * @fence_fd: the sw_sync fence fd (in)
> + *
> + * Return the earliest deadline set on the fence. The timebase for the
> + * deadline is CLOCK_MONOTONIC (same as vblank). If there is no deadline
Mentioning vblank reads odd since this is drivers/dma-buf/. Dunno.
> + * set on the fence, this ioctl will return -ENOENT.
> + */
> +struct sw_sync_get_deadline {
> + __u64 deadline_ns;
> + __u32 pad;
> + __s32 fence_fd;
> +};
> +
> #define SW_SYNC_IOC_MAGIC 'W'
>
> #define SW_SYNC_IOC_CREATE_FENCE _IOWR(SW_SYNC_IOC_MAGIC, 0,\
> struct sw_sync_create_fence_data)
>
> #define SW_SYNC_IOC_INC _IOW(SW_SYNC_IOC_MAGIC, 1, __u32)
> +#define SW_SYNC_GET_DEADLINE _IOWR(SW_SYNC_IOC_MAGIC, 2, \
> + struct sw_sync_get_deadline)
> +
> +
> +#define SW_SYNC_HAS_DEADLINE_BIT DMA_FENCE_FLAG_USER_BITS
>
> static const struct dma_fence_ops timeline_fence_ops;
>
> @@ -171,6 +192,22 @@ static void timeline_fence_timeline_value_str(struct dma_fence *fence,
> snprintf(str, size, "%d", parent->value);
> }
>
> +static void timeline_fence_set_deadline(struct dma_fence *fence, ktime_t deadline)
> +{
> + struct sync_pt *pt = dma_fence_to_sync_pt(fence);
> + unsigned long flags;
> +
> + spin_lock_irqsave(fence->lock, flags);
> + if (test_bit(SW_SYNC_HAS_DEADLINE_BIT, &fence->flags)) {
> + if (ktime_before(deadline, pt->deadline))
> + pt->deadline = deadline;
> + } else {
> + pt->deadline = deadline;
> + set_bit(SW_SYNC_HAS_DEADLINE_BIT, &fence->flags);
FWIW could use __set_bit to avoid needless atomic under spinlock.
> + }
> + spin_unlock_irqrestore(fence->lock, flags);
> +}
> +
> static const struct dma_fence_ops timeline_fence_ops = {
> .get_driver_name = timeline_fence_get_driver_name,
> .get_timeline_name = timeline_fence_get_timeline_name,
> @@ -179,6 +216,7 @@ static const struct dma_fence_ops timeline_fence_ops = {
> .release = timeline_fence_release,
> .fence_value_str = timeline_fence_value_str,
> .timeline_value_str = timeline_fence_timeline_value_str,
> + .set_deadline = timeline_fence_set_deadline,
> };
>
> /**
> @@ -387,6 +425,46 @@ static long sw_sync_ioctl_inc(struct sync_timeline *obj, unsigned long arg)
> return 0;
> }
>
> +static int sw_sync_ioctl_get_deadline(struct sync_timeline *obj, unsigned long arg)
> +{
> + struct sw_sync_get_deadline data;
> + struct dma_fence *fence;
> + struct sync_pt *pt;
> + int ret = 0;
> +
> + if (copy_from_user(&data, (void __user *)arg, sizeof(data)))
> + return -EFAULT;
> +
> + if (data.deadline_ns || data.pad)
> + return -EINVAL;
> +
> + fence = sync_file_get_fence(data.fence_fd);
> + if (!fence)
> + return -EINVAL;
> +
> + pt = dma_fence_to_sync_pt(fence);
> + if (!pt)
> + return -EINVAL;
> +
> + spin_lock(fence->lock);
This may need to be _irq.
> + if (test_bit(SW_SYNC_HAS_DEADLINE_BIT, &fence->flags)) {
> + data.deadline_ns = ktime_to_ns(pt->deadline);
> + } else {
> + ret = -ENOENT;
> + }
> + spin_unlock(fence->lock);
> +
> + dma_fence_put(fence);
> +
> + if (ret)
> + return ret;
> +
> + if (copy_to_user((void __user *)arg, &data, sizeof(data)))
> + return -EFAULT;
> +
> + return 0;
> +}
> +
> static long sw_sync_ioctl(struct file *file, unsigned int cmd,
> unsigned long arg)
> {
> @@ -399,6 +477,9 @@ static long sw_sync_ioctl(struct file *file, unsigned int cmd,
> case SW_SYNC_IOC_INC:
> return sw_sync_ioctl_inc(obj, arg);
>
> + case SW_SYNC_GET_DEADLINE:
> + return sw_sync_ioctl_get_deadline(obj, arg);
> +
> default:
> return -ENOTTY;
> }
> diff --git a/drivers/dma-buf/sync_debug.h b/drivers/dma-buf/sync_debug.h
> index 6176e52ba2d7..a1bdd62efccd 100644
> --- a/drivers/dma-buf/sync_debug.h
> +++ b/drivers/dma-buf/sync_debug.h
> @@ -55,11 +55,13 @@ static inline struct sync_timeline *dma_fence_parent(struct dma_fence *fence)
> * @base: base fence object
> * @link: link on the sync timeline's list
> * @node: node in the sync timeline's tree
> + * @deadline: the earliest fence deadline hint
> */
> struct sync_pt {
> struct dma_fence base;
> struct list_head link;
> struct rb_node node;
> + ktime_t deadline;
> };
>
> extern const struct file_operations sw_sync_debugfs_fops;
Regards,
Tvrtko
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