drm/i915: add panel lock assertion function

When PLLs or timing regs are changed, we need to make sure the panel
lock will allow it.

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

1 files changed, 29 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 2bf72a4b069f..491ac56199d1 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -1081,6 +1081,35 @@ static void assert_pll(struct drm_i915_private *dev_priv,
 #define assert_pll_enabled(d, p) assert_pll(d, p, true)
 #define assert_pll_disabled(d, p) assert_pll(d, p, false)
 
+static void assert_panel_unlocked(struct drm_i915_private *dev_priv,
+                                  enum pipe pipe)
+{
+        int pp_reg, lvds_reg;
+        u32 val;
+        enum pipe panel_pipe = PIPE_A;
+        bool locked = locked;
+
+        if (HAS_PCH_SPLIT(dev_priv->dev)) {
+                pp_reg = PCH_PP_CONTROL;
+                lvds_reg = PCH_LVDS;
+        } else {
+                pp_reg = PP_CONTROL;
+                lvds_reg = LVDS;
+        }
+
+        val = I915_READ(pp_reg);
+        if (!(val & PANEL_POWER_ON) ||
+            ((val & PANEL_UNLOCK_REGS) == PANEL_UNLOCK_REGS))
+                locked = false;
+
+        if (I915_READ(lvds_reg) & LVDS_PIPEB_SELECT)
+                panel_pipe = PIPE_B;
+
+        WARN(panel_pipe == pipe && locked,
+             "panel assertion failure, pipe %c regs locked\n",
+             pipe ? 'B' : 'A');
+}
+
 static void assert_pipe_enabled(struct drm_i915_private *dev_priv,
                                 enum pipe pipe)
 {