linux-kernel - Re: [PATCH v8 08/16] dma-buf/sw_sync: Add fence deadline support

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Date:   Wed, 1 Mar 2023 10:57:15 +0200
From:   Pekka Paalanen <ppaalanen@...il.com>
To:     Rob Clark <robdclark@...il.com>
Cc:     dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org,
        Daniel Vetter <daniel@...ll.ch>,
        Christian König <ckoenig.leichtzumerken@...il.com>,
        Michel Dänzer <michel@...nzer.net>,
        Tvrtko Ursulin <tvrtko.ursulin@...el.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        Alex Deucher <alexander.deucher@....com>,
        Simon Ser <contact@...rsion.fr>,
        Luben Tuikov <luben.tuikov@....com>,
        Rob Clark <robdclark@...omium.org>,
        Christian König <christian.koenig@....com>,
        Sumit Semwal <sumit.semwal@...aro.org>,
        Gustavo Padovan <gustavo@...ovan.org>,
        linux-media@...r.kernel.org (open list:SYNC FILE FRAMEWORK),
        linaro-mm-sig@...ts.linaro.org (moderated list:DMA BUFFER SHARING
        FRAMEWORK), linux-kernel@...r.kernel.org (open list)
Subject: Re: [PATCH v8 08/16] dma-buf/sw_sync: Add fence deadline support

On Tue, 28 Feb 2023 14:58:12 -0800
Rob Clark <robdclark@...il.com> 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>
> ---
>  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
> + * set on the fence, this ioctl will return -ENOENT.
> + */
> +struct sw_sync_get_deadline {
> +	__u64	deadline_ns;
> +	__u32	pad;
> +	__s32	fence_fd;
> +};

Sounds good.

> diff --git a/drivers/dma-buf/sync_debug.h b/drivers/dma-buf/sync_debug.h
> index 6176e52ba2d7..2e0146d0bdbb 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 most recently set fence deadline

Now it's the earliest deadline.

>   */
>  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;

Acked-by: Pekka Paalanen <pekka.paalanen@...labora.com>


Thanks,
pq

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