[PATCH v2] drm/i915: Cantiga+ cannot handle a hsync front porch of 0

[Jani Nikula <jani.nikula@intel.com>]

From: Chris Wilson <chris@chris-wilson.co.uk>

This addresses WaPruneModeWithIncorrectHsyncOffset.

Bugzilla: http://bugs.freedesktop.org/show_bug.cgi?id=50236
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

---

v2: drop patch 1/2, to be addressed later.
---
 drivers/gpu/drm/i915/intel_display.c |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 9730162..76516b9 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -3420,6 +3420,13 @@ static bool intel_crtc_mode_fixup(struct drm_crtc *crtc,
 	if (!(adjusted_mode->private_flags & INTEL_MODE_CRTC_TIMINGS_SET))
 		drm_mode_set_crtcinfo(adjusted_mode, 0);
 
+	/* WaPruneModeWithIncorrectHsyncOffset: Cantiga+ cannot handle modes
+	 * with a hsync front porch of 0.
+	 */
+	if ((INTEL_INFO(dev)->gen > 4 || IS_G4X(dev)) &&
+		adjusted_mode->hsync_start == adjusted_mode->hdisplay)
+		return false;
+
 	return true;
 }
 
-- 
1.7.4.1