Re: [PATCH 2/3] drm/i915: Detect page faults during hangcheck

[Daniel Vetter <daniel@ffwll.ch>]

On Mon, Mar 16, 2015 at 03:46:35PM +0200, Mika Kuoppala wrote:
> From: Chris Wilson <chris@chris-wilson.co.uk>
> 
> On Sandybridge+, the GPU provides the ERROR register for detecting page
> faults. Hook this up to our hangcheck so that we can dump the error
> state soon after such an event occurs. This would be better inside an
> interrupt handler, but it serves a purpose here as it detects that our
> initial context setup is invalid...
> 
> Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
>  drivers/gpu/drm/i915/i915_irq.c     | 5 +++++
>  drivers/gpu/drm/i915/intel_uncore.c | 2 ++
>  2 files changed, 7 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> index 49ad5fb..ea668fc 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -2929,6 +2929,11 @@ static void i915_hangcheck_elapsed(struct work_struct *work)
>  	if (!i915.enable_hangcheck)
>  		return;
>  
> +	if (INTEL_INFO(dev_priv)->gen >= 6 && I915_READ(ERROR_GEN6)) {
> +		i915_handle_error(dev, false, "GPU reported a page fault");
> +		I915_WRITE(ERROR_GEN6, 0);

Shouldn't we also at least report the bits from the ERROR register
somewhere? Or are they supremely useless?
-Daniel

> +	}
> +
>  	for_each_ring(ring, dev_priv, i) {
>  		u64 acthd;
>  		u32 seqno;
> diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
> index ab5cc94..c58535e 100644
> --- a/drivers/gpu/drm/i915/intel_uncore.c
> +++ b/drivers/gpu/drm/i915/intel_uncore.c
> @@ -359,6 +359,8 @@ static void __intel_uncore_early_sanitize(struct drm_device *dev,
>  	if (IS_GEN6(dev) || IS_GEN7(dev))
>  		__raw_i915_write32(dev_priv, GTFIFODBG,
>  				   __raw_i915_read32(dev_priv, GTFIFODBG));
> +	if (INTEL_INFO(dev)->gen >= 6)
> +		__raw_i915_write32(dev_priv, ERROR_GEN6, 0);
>  
>  	intel_uncore_forcewake_reset(dev, restore_forcewake);
>  }
> -- 
> 1.9.1
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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