[Intel-gfx] [PATCH 1/5] drm/i915: Initialise g4x watermarks for disabled pipes

[Chris Wilson]

We were using uninitialised watermarks values for disabled pipes which
were combined into a single WM register and so corrupting the values for
the enabled pipe and upsetting the display hardware.

Reported-by: Riccardo Magliocchetti <riccardo.magliocchetti at gmail.com>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=32612
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/intel_display.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index e1c6da1..f1798f2 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -3800,8 +3800,10 @@ static bool g4x_compute_wm0(struct drm_device *dev,
 	int entries, tlb_miss;
 
 	crtc = intel_get_crtc_for_plane(dev, plane);
-	if (crtc->fb == NULL || !crtc->enabled)
+	if (crtc->fb == NULL || !crtc->enabled) {
+		*cursor_wm = *plane_wm = display->guard_size;
 		return false;
+	}
 
 	htotal = crtc->mode.htotal;
 	hdisplay = crtc->mode.hdisplay;
-- 
1.7.4.1