drm/i915/glk: Validate only DSI PORT A PLL divider

As per BSPEC, GLK supports MIPI DSI 8X clk only on PORT A.
Therefore only for PORT A PLL divider value should be validated.

Signed-off-by: Madhav Chauhan <madhav.chauhan@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1487335415-14766-8-git-send-email-madhav.chauhan@intel.com

diff --git a/drivers/gpu/drm/i915/intel_dsi_pll.c b/drivers/gpu/drm/i915/intel_dsi_pll.c
index 7a7617b..2ff2ee7 100644 (file)
--- a/drivers/gpu/drm/i915/intel_dsi_pll.c
+++ b/drivers/gpu/drm/i915/intel_dsi_pll.c
@@ -206,17 +206,24 @@ static bool bxt_dsi_pll_is_enabled(struct drm_i915_private *dev_priv)
                return false;
 
        /*
-        * Both dividers must be programmed with valid values even if only one
-        * of the PLL is used, see BSpec/Broxton Clocks. Check this here for
+        * Dividers must be programmed with valid values. As per BSEPC, for
+        * GEMINLAKE only PORT A divider values are checked while for BXT
+        * both divider values are validated. Check this here for
         * paranoia, since BIOS is known to misconfigure PLLs in this way at
         * times, and since accessing DSI registers with invalid dividers
         * causes a system hang.
         */
        val = I915_READ(BXT_DSI_PLL_CTL);
-       if (!(val & BXT_DSIA_16X_MASK) || !(val & BXT_DSIC_16X_MASK)) {
-               DRM_DEBUG_DRIVER("PLL is enabled with invalid divider settings (%08x)\n",
-                                val);
-               enabled = false;
+       if (IS_GEMINILAKE(dev_priv)) {
+               if (!(val & BXT_DSIA_16X_MASK)) {
+                       DRM_DEBUG_DRIVER("Invalid PLL divider (%08x)\n", val);
+                       enabled = false;
+               }
+       } else {
+               if (!(val & BXT_DSIA_16X_MASK) || !(val & BXT_DSIC_16X_MASK)) {
+                       DRM_DEBUG_DRIVER("Invalid PLL divider (%08x)\n", val);
+                       enabled = false;
+               }
        }
 
        return enabled;