drm/i915/glk: Update Port PLL enable sequence for Geminilkae

Add steps for enabling and disabling Port PLL as per bspec.
Signed-off-by: Madhav Chauhan <madhav.chauhan@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/1480667037-11215-6-git-send-email-ander.conselvan.de.oliveira@intel.com

drivers/gpu/drm/i915/i915_reg.h

@@ -1574,6 +1574,8 @@ enum skl_disp_power_wells {
 #define   PORT_PLL_ENABLE		(1 << 31)
 #define   PORT_PLL_LOCK			(1 << 30)
 #define   PORT_PLL_REF_SEL		(1 << 27)
+#define   PORT_PLL_POWER_ENABLE		(1 << 26)
+#define   PORT_PLL_POWER_STATE		(1 << 25)
 #define BXT_PORT_PLL_ENABLE(port)	_MMIO_PORT(port, _PORT_PLL_A, _PORT_PLL_B)
 
 #define _PORT_PLL_EBB_0_A		0x162034

drivers/gpu/drm/i915/intel_dpll_mgr.c

@@ -1380,6 +1380,16 @@ static void bxt_ddi_pll_enable(struct drm_i915_private *dev_priv,
 	temp |= PORT_PLL_REF_SEL;
 	I915_WRITE(BXT_PORT_PLL_ENABLE(port), temp);
 
+	if (IS_GEMINILAKE(dev_priv)) {
+		temp = I915_READ(BXT_PORT_PLL_ENABLE(port));
+		temp |= PORT_PLL_POWER_ENABLE;
+		I915_WRITE(BXT_PORT_PLL_ENABLE(port), temp);
+
+		if (wait_for_us((I915_READ(BXT_PORT_PLL_ENABLE(port)) &
+				 PORT_PLL_POWER_STATE), 200))
+			DRM_ERROR("Power state not set for PLL:%d\n", port);
+	}
+
 	/* Disable 10 bit clock */
 	temp = I915_READ(BXT_PORT_PLL_EBB_4(phy, ch));
 	temp &= ~PORT_PLL_10BIT_CLK_ENABLE;
@@ -1485,6 +1495,16 @@ static void bxt_ddi_pll_disable(struct drm_i915_private *dev_priv,
 	temp &= ~PORT_PLL_ENABLE;
 	I915_WRITE(BXT_PORT_PLL_ENABLE(port), temp);
 	POSTING_READ(BXT_PORT_PLL_ENABLE(port));
+
+	if (IS_GEMINILAKE(dev_priv)) {
+		temp = I915_READ(BXT_PORT_PLL_ENABLE(port));
+		temp &= ~PORT_PLL_POWER_ENABLE;
+		I915_WRITE(BXT_PORT_PLL_ENABLE(port), temp);
+
+		if (wait_for_us(!(I915_READ(BXT_PORT_PLL_ENABLE(port)) &
+				PORT_PLL_POWER_STATE), 200))
+			DRM_ERROR("Power state not reset for PLL:%d\n", port);
+	}
 }
 
 static bool bxt_ddi_pll_get_hw_state(struct drm_i915_private *dev_priv,