Re: [PATCH] drm/i915: Clear intel_crtc->atomic before updating it.

From: "Ville Syrjälä" <ville.syrjala@linux.intel.com>
To: Maarten Lankhorst <dev@mblankhorst.nl>
Cc: Intel Graphics Development <intel-gfx@lists.freedesktop.org>
Subject: Re: [PATCH] drm/i915: Clear intel_crtc->atomic before updating it.
Date: Mon, 16 Nov 2015 15:15:40 +0200	[thread overview]
Message-ID: <20151116131540.GK4437@intel.com> (raw)
In-Reply-To: <5649C2F5.1050804@mblankhorst.nl>

On Mon, Nov 16, 2015 at 12:50:13PM +0100, Maarten Lankhorst wrote:
> If an atomic update fails intel_crtc->atomic may have have some values left
> from the last atomic check. One example is atomic->wait_for_vblank,
> which results in spurious errors in kms_flip.
> 
> Testcase: kms_flip
> Reported-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Cc: stable@vger.kernel.org #v4.3
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> ---
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index b5f7493213b7..b9539b14fe0d 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -13141,6 +13141,9 @@ static int intel_atomic_check(struct drm_device *dev,
>  		struct intel_crtc_state *pipe_config =
>  			to_intel_crtc_state(crtc_state);
>  
> +		memset(&to_intel_crtc(crtc)->atomic, 0,
> +		       sizeof(struct intel_crtc_atomic_commit));

sizeof(to_intel_crtc(crtc)->atomic) would be better.

This cures a ton of "wait_for_vblank called with a disabled pipe"
type of errors.

Tested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

> +
>  		/* Catch I915_MODE_FLAG_INHERITED */
>  		if (crtc_state->mode.private_flags != crtc->state->mode.private_flags)
>  			crtc_state->mode_changed = true;

-- 
Ville Syrjälä
Intel OTC
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