linux-kernel - Re: [Linaro-mm-sig] [PATCH] drm/msm: Add fence->wait() op

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Message-ID: <60ffb6f3-e932-d9af-3b90-81adf0c15250@gmail.com>
Date:   Tue, 20 Jul 2021 20:03:20 +0200
From:   Christian König <ckoenig.leichtzumerken@...il.com>
To:     Rob Clark <robdclark@...il.com>, dri-devel@...ts.freedesktop.org
Cc:     Rob Clark <robdclark@...omium.org>,
        "open list:DRM DRIVER FOR MSM ADRENO GPU" 
        <freedreno@...ts.freedesktop.org>, David Airlie <airlied@...ux.ie>,
        "open list:DRM DRIVER FOR MSM ADRENO GPU" 
        <linux-arm-msm@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>,
        Christian König <christian.koenig@....com>,
        "moderated list:DMA BUFFER SHARING FRAMEWORK" 
        <linaro-mm-sig@...ts.linaro.org>, Daniel Vetter <daniel@...ll.ch>,
        Sean Paul <sean@...rly.run>,
        "open list:DMA BUFFER SHARING FRAMEWORK" 
        <linux-media@...r.kernel.org>
Subject: Re: [Linaro-mm-sig] [PATCH] drm/msm: Add fence->wait() op

Hi Rob,

Am 20.07.21 um 17:07 schrieb Rob Clark:
> From: Rob Clark <robdclark@...omium.org>
>
> Somehow we had neither ->wait() nor dma_fence_signal() calls, and no
> one noticed.  Oops.


I'm not sure if that is a good idea.

The dma_fence->wait() callback is pretty much deprecated and should not 
be used any more.

What exactly do you need that for?

Regards,
Christian.

>
> Note that this removes the !timeout case, which has not been used in
> a long time.


>
> Signed-off-by: Rob Clark <robdclark@...omium.org>
> ---
>   drivers/gpu/drm/msm/msm_fence.c | 59 +++++++++++++++++++--------------
>   1 file changed, 34 insertions(+), 25 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/msm_fence.c b/drivers/gpu/drm/msm/msm_fence.c
> index cd59a5918038..8ee96b90ded6 100644
> --- a/drivers/gpu/drm/msm/msm_fence.c
> +++ b/drivers/gpu/drm/msm/msm_fence.c
> @@ -38,11 +38,10 @@ static inline bool fence_completed(struct msm_fence_context *fctx, uint32_t fenc
>   	return (int32_t)(fctx->completed_fence - fence) >= 0;
>   }
>   
> -/* legacy path for WAIT_FENCE ioctl: */
> -int msm_wait_fence(struct msm_fence_context *fctx, uint32_t fence,
> -		ktime_t *timeout, bool interruptible)
> +static signed long wait_fence(struct msm_fence_context *fctx, uint32_t fence,
> +		signed long remaining_jiffies, bool interruptible)
>   {
> -	int ret;
> +	signed long ret;
>   
>   	if (fence > fctx->last_fence) {
>   		DRM_ERROR_RATELIMITED("%s: waiting on invalid fence: %u (of %u)\n",
> @@ -50,33 +49,34 @@ int msm_wait_fence(struct msm_fence_context *fctx, uint32_t fence,
>   		return -EINVAL;
>   	}
>   
> -	if (!timeout) {
> -		/* no-wait: */
> -		ret = fence_completed(fctx, fence) ? 0 : -EBUSY;
> +	if (interruptible) {
> +		ret = wait_event_interruptible_timeout(fctx->event,
> +			fence_completed(fctx, fence),
> +			remaining_jiffies);
>   	} else {
> -		unsigned long remaining_jiffies = timeout_to_jiffies(timeout);
> -
> -		if (interruptible)
> -			ret = wait_event_interruptible_timeout(fctx->event,
> -				fence_completed(fctx, fence),
> -				remaining_jiffies);
> -		else
> -			ret = wait_event_timeout(fctx->event,
> -				fence_completed(fctx, fence),
> -				remaining_jiffies);
> -
> -		if (ret == 0) {
> -			DBG("timeout waiting for fence: %u (completed: %u)",
> -					fence, fctx->completed_fence);
> -			ret = -ETIMEDOUT;
> -		} else if (ret != -ERESTARTSYS) {
> -			ret = 0;
> -		}
> +		ret = wait_event_timeout(fctx->event,
> +			fence_completed(fctx, fence),
> +			remaining_jiffies);
> +	}
> +
> +	if (ret == 0) {
> +		DBG("timeout waiting for fence: %u (completed: %u)",
> +				fence, fctx->completed_fence);
> +		ret = -ETIMEDOUT;
> +	} else if (ret != -ERESTARTSYS) {
> +		ret = 0;
>   	}
>   
>   	return ret;
>   }
>   
> +/* legacy path for WAIT_FENCE ioctl: */
> +int msm_wait_fence(struct msm_fence_context *fctx, uint32_t fence,
> +		ktime_t *timeout, bool interruptible)
> +{
> +	return wait_fence(fctx, fence, timeout_to_jiffies(timeout), interruptible);
> +}
> +
>   /* called from workqueue */
>   void msm_update_fence(struct msm_fence_context *fctx, uint32_t fence)
>   {
> @@ -114,10 +114,19 @@ static bool msm_fence_signaled(struct dma_fence *fence)
>   	return fence_completed(f->fctx, f->base.seqno);
>   }
>   
> +static signed long msm_fence_wait(struct dma_fence *fence, bool intr,
> +		signed long timeout)
> +{
> +	struct msm_fence *f = to_msm_fence(fence);
> +
> +	return wait_fence(f->fctx, fence->seqno, timeout, intr);
> +}
> +
>   static const struct dma_fence_ops msm_fence_ops = {
>   	.get_driver_name = msm_fence_get_driver_name,
>   	.get_timeline_name = msm_fence_get_timeline_name,
>   	.signaled = msm_fence_signaled,
> +	.wait = msm_fence_wait,
>   };
>   
>   struct dma_fence *