drm/i915: add PANEL_UNLOCK_REGS definition

In some cases, unlocking the panel regs is safe and can help us avoid a
flickery, full mode set sequence.  So define the unlock key and use it.

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Eric Anholt <eric@anholt.net>

2 files changed, 5 insertions, 2 deletions

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 150400f40534..c41f945283ab 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -2805,6 +2805,7 @@
 
 #define PCH_PP_STATUS           0xc7200
 #define PCH_PP_CONTROL          0xc7204
+#define  PANEL_UNLOCK_REGS      (0xabcd << 16)
 #define  EDP_FORCE_VDD          (1 << 3)
 #define  EDP_BLC_ENABLE         (1 << 2)
 #define  PANEL_POWER_RESET      (1 << 1)
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index f28691f9742a..6d5477c5df04 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -4413,7 +4413,8 @@ static void intel_increase_pllclock(struct drm_crtc *crtc, bool schedule)
                 DRM_DEBUG_DRIVER("upclocking LVDS\n");
 
                 /* Unlock panel regs */
-                I915_WRITE(PP_CONTROL, I915_READ(PP_CONTROL) | (0xabcd << 16));
+                I915_WRITE(PP_CONTROL, I915_READ(PP_CONTROL) |
+                           PANEL_UNLOCK_REGS);
 
                 dpll &= ~DISPLAY_RATE_SELECT_FPA1;
                 I915_WRITE(dpll_reg, dpll);
@@ -4456,7 +4457,8 @@ static void intel_decrease_pllclock(struct drm_crtc *crtc)
                 DRM_DEBUG_DRIVER("downclocking LVDS\n");
 
                 /* Unlock panel regs */
-                I915_WRITE(PP_CONTROL, I915_READ(PP_CONTROL) | (0xabcd << 16));
+                I915_WRITE(PP_CONTROL, I915_READ(PP_CONTROL) |
+                           PANEL_UNLOCK_REGS);
 
                 dpll |= DISPLAY_RATE_SELECT_FPA1;
                 I915_WRITE(dpll_reg, dpll);