drm/i915: assert panel is unlocked before writing transcoder timing regs

Otherwise our writes will be silently ignored.

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 515e0b99f32e..f274d5b1b7c6 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -2444,7 +2444,8 @@ static void ironlake_crtc_enable(struct drm_crtc *crtc)
                 I915_WRITE(PCH_DPLL_SEL, temp);
         }
 
-        /* set transcoder timing */
+        /* set transcoder timing, panel must allow it */
+        assert_panel_unlocked(dev_priv, pipe);
         I915_WRITE(TRANS_HTOTAL(pipe), I915_READ(HTOTAL(pipe)));
         I915_WRITE(TRANS_HBLANK(pipe), I915_READ(HBLANK(pipe)));
         I915_WRITE(TRANS_HSYNC(pipe),  I915_READ(HSYNC(pipe)));