[Intel-gfx] [PATCH] drm/i915: Only warn the first time we attempt to mmio whilst suspended

[Daniel Vetter]

On Mon, Nov 24, 2014 at 08:03:12AM +0000, Chris Wilson wrote:
> In all likelihood we will do a few hundred errnoneous register
> operations if we do a single invalid register access whilst the device
> is suspended. As each instance causes a WARN, this floods the system
> logs and can make the system unresponsive.
> 
> The warning was first introduced in
> commit b2ec142cb0101f298f8e091c7d75b1ec5b809b65
> Author: Paulo Zanoni <paulo.r.zanoni at intel.com>
> Date:   Fri Feb 21 13:52:25 2014 -0300
> 
>     drm/i915: call assert_device_not_suspended at gen6_force_wake_work
> 
> and despite the claims the WARN is still encountered in the wild today.
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Paulo Zanoni <paulo.r.zanoni at intel.com>
> Cc: Imre Deak <imre.deak at intel.com>
> Cc: stable at vger.kernel.org

I'll pick this up queued for 3.19 (but haven't done the split yet).
-Daniel
> ---
>  drivers/gpu/drm/i915/intel_uncore.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
> index 1a3e485a4f97..f0230b0e8e11 100644
> --- a/drivers/gpu/drm/i915/intel_uncore.c
> +++ b/drivers/gpu/drm/i915/intel_uncore.c
> @@ -43,8 +43,8 @@
>  static void
>  assert_device_not_suspended(struct drm_i915_private *dev_priv)
>  {
> -	WARN(HAS_RUNTIME_PM(dev_priv->dev) && dev_priv->pm.suspended,
> -	     "Device suspended\n");
> +	WARN_ONCE(HAS_RUNTIME_PM(dev_priv->dev) && dev_priv->pm.suspended,
> +		  "Device suspended\n");
>  }
>  
>  static void __gen6_gt_wait_for_thread_c0(struct drm_i915_private *dev_priv)
> -- 
> 2.1.3
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch