[PATCH] drm/i915: Modify for pineview lvds sync polarity

[bfreed@chromium.org]

From: Bryan Freed <bfreed@google.com>

The i915 driver normally assumes the video bios has configured several
of the LVDS panel registers, and it just inherits the values. If the
vbios has not run, several of these will need to be setup.

intel_display.c: ensures the sync polarity to the panel is correct
and issues a message if the driver changes it.

If these are not correct then although the panel looks ok, output from an HDMI
encoder (eg, Chrontel CH7036) will be incorrect.

Signed-off-by: Mark Hayter <mdhayter@chromium.org>
---
 drivers/gpu/drm/i915/i915_reg.h      |    4 ++++
 drivers/gpu/drm/i915/intel_display.c |   17 +++++++++++++++++
 2 files changed, 21 insertions(+), 0 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index cb8f434..c0386e2 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -1320,6 +1320,10 @@
 #define   LVDS_PIPEB_SELECT		(1 << 30)
 /* LVDS dithering flag on 965/g4x platform */
 #define   LVDS_ENABLE_DITHER		(1 << 25)
+/* LVDS sync polarity flags. Set to invert (i.e. negative) */
+#define   LVDS_VSYNC_POLARITY		(1 << 21)
+#define   LVDS_HSYNC_POLARITY		(1 << 20)
+
 /* Enable border for unscaled (or aspect-scaled) display */
 #define   LVDS_BORDER_ENABLE		(1 << 15)
 /*
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 394446d..6336927 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -3604,6 +3604,7 @@ static int intel_crtc_mode_set(struct drm_crtc *crtc,
 	int ret;
 	struct fdi_m_n m_n = {0};
 	u32 reg, temp;
+	u32 lvds_sync = 0;
 	int target_clock;
 
 	drm_vblank_pre_modeset(dev, pipe);
@@ -4040,6 +4041,22 @@ static int intel_crtc_mode_set(struct drm_crtc *crtc,
 			else
 				temp &= ~LVDS_ENABLE_DITHER;
 		}
+		if (adjusted_mode->flags & DRM_MODE_FLAG_NHSYNC)
+			lvds_sync |= LVDS_HSYNC_POLARITY;
+		if (adjusted_mode->flags & DRM_MODE_FLAG_NVSYNC)
+			lvds_sync |= LVDS_VSYNC_POLARITY;
+		if ((temp & (LVDS_HSYNC_POLARITY | LVDS_VSYNC_POLARITY))
+		    != lvds_sync) {
+			char flags[2] = "-+";
+			DRM_INFO("Changing LVDS panel from "
+				 "(%chsync, %cvsync) to (%chsync, %cvsync)\n",
+				 flags[!(temp & LVDS_HSYNC_POLARITY)],
+				 flags[!(temp & LVDS_VSYNC_POLARITY)],
+				 flags[!(lvds_sync & LVDS_HSYNC_POLARITY)],
+				 flags[!(lvds_sync & LVDS_VSYNC_POLARITY)]);
+			temp &= ~(LVDS_HSYNC_POLARITY | LVDS_VSYNC_POLARITY);
+			temp |= lvds_sync;
+		}
 		I915_WRITE(reg, temp);
 	}
 
-- 
1.7.3.1