[Intel-gfx] [PATCH 1/3] drm/i915: set up PIPECONF explicitly on ilk-ivb

[Daniel Vetter]

Dragging random garbage along from the BIOS isn't a good idea, since
we really only support exactly what we've set up.

In the specific case for the bug reporter the BIOS used the 10bit
gamma table, but since we only support an 8bit table the dark colors
ended up all wrong and the light ones all unadjusted.

Note that this has a nice implication for fastboot, it essentially
means that we have quite a bit more state to check and compare before
we can decide whether fastboot is possible.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=65593
Reported-and-Tested-by: Thomas Hebb <tommyhebb at gmail.com>
Cc: stable at vger.kernel.org
Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
---
 drivers/gpu/drm/i915/intel_display.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 85e023f..01f26b03 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -5298,9 +5298,8 @@ static void ironlake_set_pipeconf(struct drm_crtc *crtc)
 	int pipe = intel_crtc->pipe;
 	uint32_t val;
 
-	val = I915_READ(PIPECONF(pipe));
+	val = 0;
 
-	val &= ~PIPECONF_BPC_MASK;
 	switch (intel_crtc->config.pipe_bpp) {
 	case 18:
 		val |= PIPECONF_6BPC;
@@ -5319,11 +5318,9 @@ static void ironlake_set_pipeconf(struct drm_crtc *crtc)
 		BUG();
 	}
 
-	val &= ~(PIPECONF_DITHER_EN | PIPECONF_DITHER_TYPE_MASK);
 	if (intel_crtc->config.dither)
 		val |= (PIPECONF_DITHER_EN | PIPECONF_DITHER_TYPE_SP);
 
-	val &= ~PIPECONF_INTERLACE_MASK;
 	if (intel_crtc->config.adjusted_mode.flags & DRM_MODE_FLAG_INTERLACE)
 		val |= PIPECONF_INTERLACED_ILK;
 	else
@@ -5331,8 +5328,6 @@ static void ironlake_set_pipeconf(struct drm_crtc *crtc)
 
 	if (intel_crtc->config.limited_color_range)
 		val |= PIPECONF_COLOR_RANGE_SELECT;
-	else
-		val &= ~PIPECONF_COLOR_RANGE_SELECT;
 
 	I915_WRITE(PIPECONF(pipe), val);
 	POSTING_READ(PIPECONF(pipe));
-- 
1.7.11.7