drm/i915: Honour LVDS sync polarity from EDID
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. So we need to
check that the LVDS sync polarity is correctly configured per any
available modelines (e.g. EDID) and adjust if not, issuing a warning as
we do.
Signed-off-by: Mark Hayter <mdhayter@chromium.org>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 810cfa8..4c71f56 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -1437,6 +1437,10 @@
#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 a90d65d..2c7e90f 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -4304,6 +4304,7 @@
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);
@@ -4755,6 +4756,22 @@
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);
}