drm/i915/bxt: Don't reprogram an already enabled DDI PHY

If BIOS has already programmed and enabled a PHY, don't reprogram it as
that may interfere with the currently active outputs. A follow-up patch
will add state verification, so we can catch any misconfiguration on
BIOS's behalf.

Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1459515767-29228-14-git-send-email-imre.deak@intel.com

diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index ad8f50e..a3db4da 100644 (file)
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -1722,12 +1722,52 @@ static void intel_disable_ddi(struct intel_encoder *intel_encoder)
        }
 }
 
+static bool broxton_phy_is_enabled(struct drm_i915_private *dev_priv,
+                                  enum dpio_phy phy)
+{
+       if (!(I915_READ(BXT_P_CR_GT_DISP_PWRON) & GT_DISPLAY_POWER_ON(phy)))
+               return false;
+
+       if ((I915_READ(BXT_PORT_CL1CM_DW0(phy)) &
+            (PHY_POWER_GOOD | PHY_RESERVED)) != PHY_POWER_GOOD) {
+               DRM_DEBUG_DRIVER("DDI PHY %d powered, but power hasn't settled\n",
+                                phy);
+
+               return false;
+       }
+
+       if (phy == DPIO_PHY1 &&
+           !(I915_READ(BXT_PORT_REF_DW3(DPIO_PHY1)) & GRC_DONE)) {
+               DRM_DEBUG_DRIVER("DDI PHY 1 powered, but GRC isn't done\n");
+
+               return false;
+       }
+
+       if (!(I915_READ(BXT_PHY_CTL_FAMILY(phy)) & COMMON_RESET_DIS)) {
+               DRM_DEBUG_DRIVER("DDI PHY %d powered, but still in reset\n",
+                                phy);
+
+               return false;
+       }
+
+       return true;
+}
+
 static void broxton_phy_init(struct drm_i915_private *dev_priv,
                             enum dpio_phy phy)
 {
        enum port port;
        u32 ports, val;
 
+       if (broxton_phy_is_enabled(dev_priv, phy)) {
+               DRM_DEBUG_DRIVER("DDI PHY %d already enabled, "
+                                "won't reprogram it\n", phy);
+
+               return;
+       }
+
+       DRM_DEBUG_DRIVER("DDI PHY %d not enabled, enabling it\n", phy);
+
        val = I915_READ(BXT_P_CR_GT_DISP_PWRON);
        val |= GT_DISPLAY_POWER_ON(phy);
        I915_WRITE(BXT_P_CR_GT_DISP_PWRON, val);