[Intel-gfx] [PATCH] drm/i915: Flush using only the correct base address register

[Damien Lespiau]

From: Damien Lespiau <damien.lespiau at intel.com>

We were writing DSP_ADDR and DSP_SURF unconditionally. This did not
trigger an unclaimed write before HSW as the address of DSP_ADDR has
been repurposed as DSP_LINOFF.

On HSW, though, DSP_LINOFF has been removed and then writting to it
triggers an unclaimed write.

This patch writes to DSP_ADDR or DSP_SURF to flush the display plane
configuration depending on the gen we're running on.

Signed-off-by: Damien Lespiau <damien.lespiau at intel.com>
---
 drivers/gpu/drm/i915/intel_display.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index a038e4f..f32244b 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -1836,8 +1836,10 @@ static void intel_disable_pipe(struct drm_i915_private *dev_priv,
 void intel_flush_display_plane(struct drm_i915_private *dev_priv,
 				      enum plane plane)
 {
-	I915_WRITE(DSPADDR(plane), I915_READ(DSPADDR(plane)));
-	I915_WRITE(DSPSURF(plane), I915_READ(DSPSURF(plane)));
+	if (dev_priv->info->gen >= 4)
+		I915_WRITE(DSPSURF(plane), I915_READ(DSPSURF(plane)));
+	else
+		I915_WRITE(DSPADDR(plane), I915_READ(DSPADDR(plane)));
 }
 
 /**
-- 
1.7.7.5