[Intel-gfx] [PATCH] drm/i915: Cancel hangcheck before GPU is suspended

[Imre Deak]

On ke, 2015-12-09 at 15:56 +0200, Joonas Lahtinen wrote:
> In order to avoid accessing GPU registers while GPU is suspended
> cancel
> the hangcheck work before calling intel_suspend_complete which
> actually
> puts the GPU to suspend. Otherwise hangcheck might do MMIO reads to a
> suspended GPU.
> 
> Placement before intel_guc_suspend is imitated from i915_drm_suspend
> which cancels the work at i915_gem_suspend, to keep the functions
> similar.
> 
> On VLV systems, namely BYT, this was causing an error during runtime
> suspend cycle:
> 
> [drm:vlv_check_no_gt_access [i915]] *ERROR* GT register access while
> GT waking disabled
> 
> Testcase: igt/pm_rpm/basic-rte
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=93121
> 
> Signed-off-by: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> Cc: Imre Deak <imre.deak at intel.com>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>

Yep, looks good to me:
Reviewed-by: Imre Deak <imre.deak at intel.com>

> ---
>  drivers/gpu/drm/i915/i915_drv.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.c
> b/drivers/gpu/drm/i915/i915_drv.c
> index e6935f1..81862d5 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -1462,6 +1462,8 @@ static int intel_runtime_suspend(struct device
> *device)
>  	i915_gem_release_all_mmaps(dev_priv);
>  	mutex_unlock(&dev->struct_mutex);
>  
> +	cancel_delayed_work_sync(&dev_priv-
> >gpu_error.hangcheck_work);
> +
>  	intel_guc_suspend(dev);
>  
>  	intel_suspend_gt_powersave(dev);
> @@ -1475,7 +1477,6 @@ static int intel_runtime_suspend(struct device
> *device)
>  		return ret;
>  	}
>  
> -	cancel_delayed_work_sync(&dev_priv-
> >gpu_error.hangcheck_work);
>  	intel_uncore_forcewake_reset(dev, false);
>  	dev_priv->pm.suspended = true;
>