drm/i915/glk: Set DCC delay range 2 in PLL enable sequence

Follow the PLL enable sequence updated in bspec, which requires the DCC
delay range 2 bit to be set.

v2: Moved from DDI init sequence to PLL enable.
v3: Don't read value from GRP register. (Rodrido)

Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Ander Conselvan De Oliveira <ander.conselvan.de.oliveira@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1480667037-11215-5-git-send-email-ander.conselvan.de.oliveira@intel.com
diff --git a/drivers/gpu/drm/i915/intel_dpll_mgr.c b/drivers/gpu/drm/i915/intel_dpll_mgr.c
index 8a82507..63104b7 100644
--- a/drivers/gpu/drm/i915/intel_dpll_mgr.c
+++ b/drivers/gpu/drm/i915/intel_dpll_mgr.c
@@ -1458,6 +1458,12 @@ static void bxt_ddi_pll_enable(struct drm_i915_private *dev_priv,
 			200))
 		DRM_ERROR("PLL %d not locked\n", port);
 
+	if (IS_GEMINILAKE(dev_priv)) {
+		temp = I915_READ(BXT_PORT_TX_DW5_LN0(phy, ch));
+		temp |= DCC_DELAY_RANGE_2;
+		I915_WRITE(BXT_PORT_TX_DW5_GRP(phy, ch), temp);
+	}
+
 	/*
 	 * While we write to the group register to program all lanes at once we
 	 * can read only lane registers and we pick lanes 0/1 for that.