drm/i915: Beef up skl_sanitize_cdclk() a bit

Also verify the DPLL_CTRL1 register value in skl_sanitize_cdclk(), throw
out a few unneeded variables, and write the CDCLK_CTL check a bit more
legible way.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1463172100-24715-10-git-send-email-ville.syrjala@linux.intel.com
Reviewed-by: Imre Deak <imre.deak@intel.com>

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 2d8630f96556aa478c694ac5460d81f210be62b8..b2adb01671be02db2ccae7847f73df6fbc3a75ad 100644 (file)
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -5709,9 +5709,7 @@ void skl_init_cdclk(struct drm_i915_private *dev_priv)
 
 int skl_sanitize_cdclk(struct drm_i915_private *dev_priv)
 {
-       uint32_t lcpll1 = I915_READ(LCPLL1_CTL);
-       uint32_t cdctl = I915_READ(CDCLK_CTL);
-       int freq = dev_priv->cdclk_freq;
+       uint32_t cdctl, expected;
 
        /*
         * check if the pre-os intialized the display
@@ -5722,7 +5720,14 @@ int skl_sanitize_cdclk(struct drm_i915_private *dev_priv)
                goto sanitize;
 
        /* Is PLL enabled and locked ? */
-       if (!((lcpll1 & LCPLL_PLL_ENABLE) && (lcpll1 & LCPLL_PLL_LOCK)))
+       if ((I915_READ(LCPLL1_CTL) & (LCPLL_PLL_ENABLE | LCPLL_PLL_LOCK)) !=
+           (LCPLL_PLL_ENABLE | LCPLL_PLL_LOCK))
+               goto sanitize;
+
+       if ((I915_READ(DPLL_CTRL1) & (DPLL_CTRL1_HDMI_MODE(SKL_DPLL0) |
+                                     DPLL_CTRL1_SSC(SKL_DPLL0) |
+                                     DPLL_CTRL1_OVERRIDE(SKL_DPLL0))) !=
+           DPLL_CTRL1_OVERRIDE(SKL_DPLL0))
                goto sanitize;
 
        /* DPLL okay; verify the cdclock
@@ -5731,7 +5736,10 @@ int skl_sanitize_cdclk(struct drm_i915_private *dev_priv)
         * decimal part is programmed wrong from BIOS where pre-os does not
         * enable display. Verify the same as well.
         */
-       if (cdctl == ((cdctl & CDCLK_FREQ_SEL_MASK) | skl_cdclk_decimal(freq)))
+       cdctl = I915_READ(CDCLK_CTL);
+       expected = (cdctl & CDCLK_FREQ_SEL_MASK) |
+               skl_cdclk_decimal(dev_priv->cdclk_freq);
+       if (cdctl == expected)
                /* All well; nothing to sanitize */
                return false;
 sanitize: