[PATCH 1/3] drm/v3d: Don't resubmit guilty CSD jobs

[Chema Casanova]

I've tested the patch and confirmed that applies correctly over drm-next.

I've also confirmed that the timeout happens with the described test 
case by the developer.

https://github.com/raspberrypi/linux/pull/3816#issuecomment-682251862

Considering this is my first review of a patch in v3d kernel side I 
think this patch is fine.

Reviewed-by: Jose Maria Casanova Crespo <jmcasanova at igalia.com>

On 3/9/20 18:48, Yukimasa Sugizaki wrote:
> From: Yukimasa Sugizaki <ysugi at idein.jp>
>
> The previous code misses a check for the timeout error set by
> drm_sched_resubmit_jobs(), which results in an infinite GPU reset loop
> if once a timeout occurs:
>
> [  178.799106] v3d fec00000.v3d: [drm:v3d_reset [v3d]] *ERROR* Resetting GPU for hang.
> [  178.807836] v3d fec00000.v3d: [drm:v3d_reset [v3d]] *ERROR* V3D_ERR_STAT: 0x00001000
> [  179.839132] v3d fec00000.v3d: [drm:v3d_reset [v3d]] *ERROR* Resetting GPU for hang.
> [  179.847865] v3d fec00000.v3d: [drm:v3d_reset [v3d]] *ERROR* V3D_ERR_STAT: 0x00001000
> [  180.879146] v3d fec00000.v3d: [drm:v3d_reset [v3d]] *ERROR* Resetting GPU for hang.
> [  180.887925] v3d fec00000.v3d: [drm:v3d_reset [v3d]] *ERROR* V3D_ERR_STAT: 0x00001000
> [  181.919188] v3d fec00000.v3d: [drm:v3d_reset [v3d]] *ERROR* Resetting GPU for hang.
> [  181.928002] v3d fec00000.v3d: [drm:v3d_reset [v3d]] *ERROR* V3D_ERR_STAT: 0x00001000
> ...
>
> This commit adds the check for timeout as in v3d_{bin,render}_job_run():
>
> [   66.408962] v3d fec00000.v3d: [drm:v3d_reset [v3d]] *ERROR* Resetting GPU for hang.
> [   66.417734] v3d fec00000.v3d: [drm:v3d_reset [v3d]] *ERROR* V3D_ERR_STAT: 0x00001000
> [   66.428296] [drm] Skipping CSD job resubmission due to previous error (-125)
>
> , where -125 is -ECANCELED, though users currently have no way other
> than inspecting the dmesg to check if the timeout has occurred.
>
> Signed-off-by: Yukimasa Sugizaki <ysugi at idein.jp>
> ---
>   drivers/gpu/drm/v3d/v3d_sched.c | 11 +++++++++++
>   1 file changed, 11 insertions(+)
>
> diff --git a/drivers/gpu/drm/v3d/v3d_sched.c b/drivers/gpu/drm/v3d/v3d_sched.c
> index 0747614a78f0..001216f22017 100644
> --- a/drivers/gpu/drm/v3d/v3d_sched.c
> +++ b/drivers/gpu/drm/v3d/v3d_sched.c
> @@ -226,6 +226,17 @@ v3d_csd_job_run(struct drm_sched_job *sched_job)
>   	struct dma_fence *fence;
>   	int i;
>
> +	/* This error is set to -ECANCELED by drm_sched_resubmit_jobs() if this
> +	 * job timed out more than sched_job->sched->hang_limit times.
> +	 */
> +	int error = sched_job->s_fence->finished.error;
> +
> +	if (unlikely(error < 0)) {
> +		DRM_WARN("Skipping CSD job resubmission due to previous error (%d)\n",
> +			 error);
> +		return ERR_PTR(error);
> +	}
> +
>   	v3d->csd_job = job;
>
>   	v3d_invalidate_caches(v3d);
> --
> 2.7.4
>
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