drm/i915: don't disable a PCH DPLL that's in use

If a PCH pipe PLL is being used by transcoder C, don't disable it.

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Keith Packard <keithp@keithp.com>

1 files changed, 11 insertions, 1 deletions

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 2e00c8ae361..bdab82b999e 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -1204,7 +1204,8 @@ static void intel_disable_pch_pll(struct drm_i915_private *dev_priv,
                                   enum pipe pipe)
 {
         int reg;
-        u32 val;
+        u32 val, pll_mask = TRANSC_DPLL_ENABLE | TRANSC_DPLLB_SEL,
+                pll_sel = TRANSC_DPLL_ENABLE;
 
         if (pipe > 1)
                 return;
@@ -1215,6 +1216,15 @@ static void intel_disable_pch_pll(struct drm_i915_private *dev_priv,
         /* Make sure transcoder isn't still depending on us */
         assert_transcoder_disabled(dev_priv, pipe);
 
+        if (pipe == 0)
+                pll_sel |= TRANSC_DPLLA_SEL;
+        else if (pipe == 1)
+                pll_sel |= TRANSC_DPLLB_SEL;
+
+
+        if ((I915_READ(PCH_DPLL_SEL) & pll_mask) == pll_sel)
+                return;
+
         reg = PCH_DPLL(pipe);
         val = I915_READ(reg);
         val &= ~DPLL_VCO_ENABLE;