drm/i915: add Ivybridge clock gating init function

Some of the bits have changed, including one we were setting that enables
a VGA test mode, preventing pipe B from working at all.  So add a new
IVB specific function with the right bits.
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Reviewed-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Keith Packard <keithp@keithp.com>

drivers/gpu/drm/i915/i915_reg.h

@@ -2825,6 +2825,7 @@
 #define  ILK_eDP_A_DISABLE		(1<<24)
 #define  ILK_DESKTOP			(1<<23)
 #define ILK_DSPCLK_GATE		0x42020
+#define  IVB_VRHUNIT_CLK_GATE	(1<<28)
 #define  ILK_DPARB_CLK_GATE	(1<<5)
 #define  ILK_DPFD_CLK_GATE	(1<<7)
 

drivers/gpu/drm/i915/intel_display.c

@@ -7336,6 +7336,33 @@ static void gen6_init_clock_gating(struct drm_device *dev)
 			   DISPPLANE_TRICKLE_FEED_DISABLE);
 }
 
+static void ivybridge_init_clock_gating(struct drm_device *dev)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	int pipe;
+	uint32_t dspclk_gate = VRHUNIT_CLOCK_GATE_DISABLE;
+
+	I915_WRITE(PCH_DSPCLK_GATE_D, dspclk_gate);
+
+	/*
+	 * On Ibex Peak and Cougar Point, we need to disable clock
+	 * gating for the panel power sequencer or it will fail to
+	 * start up when no ports are active.
+	 */
+	I915_WRITE(SOUTH_DSPCLK_GATE_D, PCH_DPLSUNIT_CLOCK_GATE_DISABLE);
+
+	I915_WRITE(WM3_LP_ILK, 0);
+	I915_WRITE(WM2_LP_ILK, 0);
+	I915_WRITE(WM1_LP_ILK, 0);
+
+	I915_WRITE(ILK_DSPCLK_GATE, IVB_VRHUNIT_CLK_GATE);
+
+	for_each_pipe(pipe)
+		I915_WRITE(DSPCNTR(pipe),
+			   I915_READ(DSPCNTR(pipe)) |
+			   DISPPLANE_TRICKLE_FEED_DISABLE);
+}
+
 static void g4x_init_clock_gating(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
@@ -7603,7 +7630,7 @@ static void intel_init_display(struct drm_device *dev)
 					      "Disable CxSR\n");
 				dev_priv->display.update_wm = NULL;
 			}
-			dev_priv->display.init_clock_gating = gen6_init_clock_gating;
+			dev_priv->display.init_clock_gating = ivybridge_init_clock_gating;
 
 		} else
 			dev_priv->display.update_wm = NULL;