[Intel-gfx] [PATCH 3/4] drm/i915: Detect and clear unclaimed access on resume

[Chris Wilson]

On Wed, Dec 09, 2015 at 05:01:40PM +0200, Mika Kuoppala wrote:
> If something, the usual suspect being bios, access hw
> behind our back, dont let it slide into situation where
> normal register access will detect this and spit out
> a warn on into dmesg. On some bdw bioses this happens
> during igt/bat run always and as there is not much we can
> do about it, its better just to detect and flush this
> explicitly on resume and only print a debug message.
> 
> Testcase: igt/pm_rpm/basic-rte
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Paulo Zanoni <przanoni at gmail.com>
> Cc: Daniel Vetter <daniel.vetter at intel.com>
> Signed-off-by: Mika Kuoppala <mika.kuoppala at intel.com>
> ---
>  drivers/gpu/drm/i915/i915_drv.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> index e6935f1..4efe7f0 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -1477,6 +1477,9 @@ static int intel_runtime_suspend(struct device *device)
>  
>  	cancel_delayed_work_sync(&dev_priv->gpu_error.hangcheck_work);
>  	intel_uncore_forcewake_reset(dev, false);
> +	if (intel_uncore_unclaimed_access(dev))
> +		DRM_ERROR("Unclaimed access detected prior suspending\n");
> +
>  	dev_priv->pm.suspended = true;
>  
>  	/*
> @@ -1522,6 +1525,8 @@ static int intel_runtime_resume(struct device *device)
>  
>  	intel_opregion_notify_adapter(dev, PCI_D0);
>  	dev_priv->pm.suspended = false;
> +	if (intel_uncore_unclaimed_access(dev))
> +		DRM_DEBUG_KMS("Unclaimed access during suspend, bios?\n");

DRM_DEBUG_DRIVER(), is this not modesetting related.

Other than that, looks like a good idea. Now I just need to see some
patches to see what intel_uncore_unclaimed_access() does... 
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre