linux-kernel - Re: [PATCH 1/2] drm/msm: Drop update

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Date:   Wed, 15 Jun 2022 13:03:03 -0500
From:   Steev Klimaszewski <steev@...i.org>
To:     Rob Clark <robdclark@...il.com>, dri-devel@...ts.freedesktop.org
Cc:     freedreno@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org,
        Rob Clark <robdclark@...omium.org>,
        Abhinav Kumar <quic_abhinavk@...cinc.com>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Sean Paul <sean@...rly.run>, David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] drm/msm: Drop update_fences()


On 6/15/22 10:01 AM, Rob Clark wrote:
> From: Rob Clark <robdclark@...omium.org>
>
> I noticed while looking at some traces, that we could miss calls to
> msm_update_fence(), as the irq could have raced with retire_submits()
> which could have already popped the last submit on a ring out of the
> queue of in-flight submits.  But walking the list of submits in the
> irq handler isn't really needed, as dma_fence_is_signaled() will dtrt.
> So lets just drop it entirely.
>
> Reported-by: Steev Klimaszewski <steev@...i.org>
> Fixes: 95d1deb02a9c ("drm/msm/gem: Add fenced vma unpin")
> Signed-off-by: Rob Clark <robdclark@...omium.org>
> ---
>   drivers/gpu/drm/msm/msm_gpu.c | 22 ++--------------------
>   1 file changed, 2 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/msm_gpu.c b/drivers/gpu/drm/msm/msm_gpu.c
> index e59a757578df..b61078f0cd0f 100644
> --- a/drivers/gpu/drm/msm/msm_gpu.c
> +++ b/drivers/gpu/drm/msm/msm_gpu.c
> @@ -176,24 +176,6 @@ int msm_gpu_hw_init(struct msm_gpu *gpu)
>   	return ret;
>   }
>   
> -static void update_fences(struct msm_gpu *gpu, struct msm_ringbuffer *ring,
> -		uint32_t fence)
> -{
> -	struct msm_gem_submit *submit;
> -	unsigned long flags;
> -
> -	spin_lock_irqsave(&ring->submit_lock, flags);
> -	list_for_each_entry(submit, &ring->submits, node) {
> -		if (fence_after(submit->seqno, fence))
> -			break;
> -
> -		msm_update_fence(submit->ring->fctx,
> -			submit->hw_fence->seqno);
> -		dma_fence_signal(submit->hw_fence);
> -	}
> -	spin_unlock_irqrestore(&ring->submit_lock, flags);
> -}
> -
>   #ifdef CONFIG_DEV_COREDUMP
>   static ssize_t msm_gpu_devcoredump_read(char *buffer, loff_t offset,
>   		size_t count, void *data, size_t datalen)
> @@ -450,7 +432,7 @@ static void recover_worker(struct kthread_work *work)
>   		if (ring == cur_ring)
>   			fence++;
>   
> -		update_fences(gpu, ring, fence);
> +		msm_update_fence(ring->fctx, fence);
>   	}
>   
>   	if (msm_gpu_active(gpu)) {
> @@ -753,7 +735,7 @@ void msm_gpu_retire(struct msm_gpu *gpu)
>   	int i;
>   
>   	for (i = 0; i < gpu->nr_rings; i++)
> -		update_fences(gpu, gpu->rb[i], gpu->rb[i]->memptrs->fence);
> +		msm_update_fence(gpu->rb[i]->fctx, gpu->rb[i]->memptrs->fence);
>   
>   	kthread_queue_work(gpu->worker, &gpu->retire_work);
>   	update_sw_cntrs(gpu);


Tested on the Lenovo Yoga C630

Tested-by: Steev Klimaszewski <steev@...i.org>