[Intel-gfx] [PATCH] drm/i915: Report an error when i915.reset prevents a reset

[Daniel Vetter]

On Thu, Jun 18, 2015 at 11:42:08AM +0100, Chris Wilson wrote:
> If the user disables the GPU reset using the i915.reset parameter and
> one occurs, report that we failed to reset the GPU. If we return early,
> as we currently do, then we leave all state intact (with a hung GPU)
> and clients block forever waiting for their requests to complete.
> 
> Testcase: igt/gem_eio
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> ---
>  drivers/gpu/drm/i915/i915_dma.c     | 1 -
>  drivers/gpu/drm/i915/i915_drv.c     | 3 ---
>  drivers/gpu/drm/i915/intel_uncore.c | 3 +++
>  3 files changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
> index 88795d2f1819..c5349fa3fcce 100644
> --- a/drivers/gpu/drm/i915/i915_dma.c
> +++ b/drivers/gpu/drm/i915/i915_dma.c
> @@ -165,7 +165,6 @@ static int i915_getparam(struct drm_device *dev, void *data,
>  		break;
>  	case I915_PARAM_HAS_GPU_RESET:
>  		value = i915.enable_hangcheck &&
> -			i915.reset &&
>  			intel_has_gpu_reset(dev);
>  		break;
>  	default:
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> index 78ef0bb53c36..25ffe8afe744 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -863,9 +863,6 @@ int i915_reset(struct drm_device *dev)
>  	bool simulated;
>  	int ret;
>  
> -	if (!i915.reset)
> -		return 0;
> -
>  	intel_reset_gt_powersave(dev);
>  
>  	mutex_lock(&dev->struct_mutex);
> diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
> index 4a86cf007aa0..f8e75def1a1d 100644
> --- a/drivers/gpu/drm/i915/intel_uncore.c
> +++ b/drivers/gpu/drm/i915/intel_uncore.c
> @@ -1457,6 +1457,9 @@ static int gen6_do_reset(struct drm_device *dev)
>  
>  static int (*intel_get_gpu_reset(struct drm_device *dev))(struct drm_device *)
>  {
> +	if (!i915.reset)
> +		return NULL;

Maybe a special reset function which always returns -EIO and prints
something to illuminate the situation to dmesg? Otherwise even more wtf
material in bugzilla ...
-Daniel

> +
>  	if (INTEL_INFO(dev)->gen >= 6)
>  		return gen6_do_reset;
>  	else if (IS_GEN5(dev))
> -- 
> 2.1.4
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch