On 2023-02-18 16:15, Rob Clark wrote:
> From: Rob Clark <robdclark@xxxxxxxxxxxx>
>
> Add a way to hint to the fence signaler of an upcoming deadline, such as
> vblank, which the fence waiter would prefer not to miss. This is to aid
> the fence signaler in making power management decisions, like boosting
> frequency as the deadline approaches and awareness of missing deadlines
> so that can be factored in to the frequency scaling.
>
> v2: Drop dma_fence::deadline and related logic to filter duplicate
> deadlines, to avoid increasing dma_fence size. The fence-context
> implementation will need similar logic to track deadlines of all
> the fences on the same timeline. [ckoenig]
> v3: Clarify locking wrt. set_deadline callback
>
> Signed-off-by: Rob Clark <robdclark@xxxxxxxxxxxx>
> Reviewed-by: Christian König <christian.koenig@xxxxxxx>
> ---
> drivers/dma-buf/dma-fence.c | 20 ++++++++++++++++++++
> include/linux/dma-fence.h | 20 ++++++++++++++++++++
> 2 files changed, 40 insertions(+)
>
> diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c
> index 0de0482cd36e..763b32627684 100644
> --- a/drivers/dma-buf/dma-fence.c
> +++ b/drivers/dma-buf/dma-fence.c
> @@ -912,6 +912,26 @@ dma_fence_wait_any_timeout(struct dma_fence **fences, uint32_t count,
> }
> EXPORT_SYMBOL(dma_fence_wait_any_timeout);
>
> +
> +/**
The added empty line above creates a problem for scripts/checkpatch.pl--and
there's a few others here and there. It'd be a good idea to run this series
through checkpatch.pl, if at least informatively.
I wasn't able to apply patch 13 to drm-misc-next or any other known to me
branch, and I didn't see base tree information in the cover letter. I skipped
it and it compiled okay without it.
--
Regards,
Luben
> + * dma_fence_set_deadline - set desired fence-wait deadline
> + * @fence: the fence that is to be waited on
> + * @deadline: the time by which the waiter hopes for the fence to be
> + * signaled
> + *
> + * Inform the fence signaler of an upcoming deadline, such as vblank, by
> + * which point the waiter would prefer the fence to be signaled by. This
> + * is intended to give feedback to the fence signaler to aid in power
> + * management decisions, such as boosting GPU frequency if a periodic
> + * vblank deadline is approaching.
> + */
> +void dma_fence_set_deadline(struct dma_fence *fence, ktime_t deadline)
> +{
> + if (fence->ops->set_deadline && !dma_fence_is_signaled(fence))
> + fence->ops->set_deadline(fence, deadline);
> +}
> +EXPORT_SYMBOL(dma_fence_set_deadline);
> +
> /**
> * dma_fence_describe - Dump fence describtion into seq_file
> * @fence: the 6fence to describe
> diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h
> index 775cdc0b4f24..d77f6591c453 100644
> --- a/include/linux/dma-fence.h
> +++ b/include/linux/dma-fence.h
> @@ -99,6 +99,7 @@ enum dma_fence_flag_bits {
> DMA_FENCE_FLAG_SIGNALED_BIT,
> DMA_FENCE_FLAG_TIMESTAMP_BIT,
> DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
> + DMA_FENCE_FLAG_HAS_DEADLINE_BIT,
> DMA_FENCE_FLAG_USER_BITS, /* must always be last member */
> };
>
> @@ -257,6 +258,23 @@ struct dma_fence_ops {
> */
> void (*timeline_value_str)(struct dma_fence *fence,
> char *str, int size);
> +
> + /**
> + * @set_deadline:
> + *
> + * Callback to allow a fence waiter to inform the fence signaler of
> + * an upcoming deadline, such as vblank, by which point the waiter
> + * would prefer the fence to be signaled by. This is intended to
> + * give feedback to the fence signaler to aid in power management
> + * decisions, such as boosting GPU frequency.
> + *
> + * This is called without &dma_fence.lock held, it can be called
> + * multiple times and from any context. Locking is up to the callee
> + * if it has some state to manage.
> + *
> + * This callback is optional.
> + */
> + void (*set_deadline)(struct dma_fence *fence, ktime_t deadline);
> };
>
> void dma_fence_init(struct dma_fence *fence, const struct dma_fence_ops *ops,
> @@ -583,6 +601,8 @@ static inline signed long dma_fence_wait(struct dma_fence *fence, bool intr)
> return ret < 0 ? ret : 0;
> }
>
> +void dma_fence_set_deadline(struct dma_fence *fence, ktime_t deadline);
> +
> struct dma_fence *dma_fence_get_stub(void);
> struct dma_fence *dma_fence_allocate_private_stub(void);
> u64 dma_fence_context_alloc(unsigned num);
