linux-kernel - [PATCH] drm/i915/tv: Flush register writes before sleeping.

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Date:	Tue, 24 Aug 2010 10:21:17 +0100
From:	Chris Wilson <chris@...is-wilson.co.uk>
To:	Ivan Bulatovic <combuster@....com>
Cc:	Chris Wilson <chris@...is-wilson.co.uk>,
	linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
	jbarnes@...tuousgeek.org, eric@...olt.net, penberg@...nel.org
Subject: [PATCH] drm/i915/tv: Flush register writes before sleeping.

Ivan, can you try this patch?

Linus is going to make some more snide comments if he sees just how many
of these trivial-ish patches that I have pending...

---

If we need to wait until the next vblank for the register to be updated
and to take effect, make sure the write is actually flushed to the register
prior to sleeping.

Signed-off-by: Chris Wilson <chris@...is-wilson.co.uk>
---
 drivers/gpu/drm/i915/intel_tv.c |    9 ++++++++-
 1 files changed, 8 insertions(+), 1 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_tv.c b/drivers/gpu/drm/i915/intel_tv.c
index d2029ef..19b9739 100644
--- a/drivers/gpu/drm/i915/intel_tv.c
+++ b/drivers/gpu/drm/i915/intel_tv.c
@@ -1157,10 +1157,13 @@ intel_tv_mode_set(struct drm_encoder *encoder, struct drm_display_mode *mode,
 		I915_WRITE(dspbase_reg, I915_READ(dspbase_reg));
 
 		/* Wait for vblank for the disable to take effect */
-		if (!IS_I9XX(dev))
+		if (!IS_I9XX(dev)) {
+			POSTING_READ(dspbase_reg);
 			intel_wait_for_vblank(dev, intel_crtc->pipe);
+		}
 
 		I915_WRITE(pipeconf_reg, pipeconf & ~PIPEACONF_ENABLE);
+		POSTING_READ(pipeconf_reg);
 		/* Wait for vblank for the disable to take effect. */
 		intel_wait_for_vblank(dev, intel_crtc->pipe);
 
@@ -1268,11 +1271,15 @@ intel_tv_detect_type (struct intel_tv *intel_tv)
 		   DAC_C_0_7_V);
 	I915_WRITE(TV_CTL, tv_ctl);
 	I915_WRITE(TV_DAC, tv_dac);
+	POSTING_READ(TV_DAC);
 	intel_wait_for_vblank(dev, intel_crtc->pipe);
+
 	tv_dac = I915_READ(TV_DAC);
 	I915_WRITE(TV_DAC, save_tv_dac);
 	I915_WRITE(TV_CTL, save_tv_ctl);
+	POSTING_READ(TV_CTL);
 	intel_wait_for_vblank(dev, intel_crtc->pipe);
+
 	/*
 	 *  A B C
 	 *  0 1 1 Composite
-- 
1.7.1

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