[PATCH 2/2] drm/i915: don't use uninitialized EDID bpc values when picking pipe bpp

[Jesse Barnes <jbarnes@virtuousgeek.org>]

The EDID parser will zero out the bpc value, and the driver needs to handle
that case.  In our picker, we'll just ignore 0 values as far as bpp
picking goes.

Fixes https://bugs.freedesktop.org/show_bug.cgi?id=39323.

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
---
 drivers/gpu/drm/i915/intel_display.c |    7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 2a367de..09d5683 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -4571,7 +4571,9 @@ static bool intel_choose_pipe_bpp_dither(struct drm_crtc *crtc,
 			if (connector->encoder != encoder)
 				continue;
 
-			if (connector->display_info.bpc < display_bpc) {
+			/* Don't use an invalid EDID bpc value */
+			if (connector->display_info.bpc &&
+			    connector->display_info.bpc < display_bpc) {
 				DRM_DEBUG_DRIVER("clamping display bpc (was %d) to EDID reported max of %d\n", display_bpc, connector->display_info.bpc);
 				display_bpc = connector->display_info.bpc;
 			}
@@ -5186,7 +5188,8 @@ static int ironlake_crtc_mode_set(struct drm_crtc *crtc,
 		temp |= PIPE_12BPC;
 		break;
 	default:
-		WARN(1, "intel_choose_pipe_bpp returned invalid value\n");
+		WARN(1, "intel_choose_pipe_bpp returned invalid value %d\n",
+			pipe_bpp);
 		temp |= PIPE_8BPC;
 		pipe_bpp = 24;
 		break;
-- 
1.7.4.1