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>

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 2e00c8a..bdab82b 100644 (file)
--- 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;