linux-kernel - [PATCH] drm/i915/ilk: Wait one vblank before enabling audio

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Date:	Fri, 20 May 2016 17:36:40 -0400
From:	Lyude <cpaul@...hat.com>
To:	intel-gfx@...ts.freedesktop.org
Cc:	Lyude <cpaul@...hat.com>, stable@...r.kernel.org,
	Daniel Vetter <daniel.vetter@...el.com>,
	Jani Nikula <jani.nikula@...ux.intel.com>,
	David Airlie <airlied@...ux.ie>,
	dri-devel@...ts.freedesktop.org (open list:INTEL DRM DRIVERS (excluding
	Poulsbo, Moorestow...), linux-kernel@...r.kernel.org (open list))
Subject: [PATCH] drm/i915/ilk: Wait one vblank before enabling audio

We no longer call ilk_audio_codec_enable() while we have vblanks
disabled. As such, we can finally fix this and stop the occasional pipe
underruns I'm seeing on this Dell OptiPlex 990.

Cc: stable@...r.kernel.org
Signed-off-by: Lyude <cpaul@...hat.com>
---
 drivers/gpu/drm/i915/intel_audio.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_audio.c b/drivers/gpu/drm/i915/intel_audio.c
index 7d281b4..0d685fe 100644
--- a/drivers/gpu/drm/i915/intel_audio.c
+++ b/drivers/gpu/drm/i915/intel_audio.c
@@ -423,12 +423,8 @@ static void ilk_audio_codec_enable(struct drm_connector *connector,
 	if (WARN_ON(port == PORT_A))
 		return;
 
-	/*
-	 * FIXME: We're supposed to wait for vblank here, but we have vblanks
-	 * disabled during the mode set. The proper fix would be to push the
-	 * rest of the setup into a vblank work item, queued here, but the
-	 * infrastructure is not there yet.
-	 */
+	/* Need to wait one vblank before enabling audio */
+	intel_wait_for_vblank(connector->dev, pipe);
 
 	if (HAS_PCH_IBX(connector->dev)) {
 		hdmiw_hdmiedid = IBX_HDMIW_HDMIEDID(pipe);
-- 
2.5.5