drm/i915: make the panel fitter work on pipes B and C on IVB

I actually found this problem on Haswell, but then discovered Ivy
Bridge also has it by reading the spec.

I don't have the hardware to test this.

Cc: stable@vger.kernel.org
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_reg.h

@@ -3339,6 +3339,8 @@
 #define _PFA_CTL_1               0x68080
 #define _PFB_CTL_1               0x68880
 #define  PF_ENABLE              (1<<31)
+#define  PF_PIPE_SEL_MASK_IVB	(3<<29)
+#define  PF_PIPE_SEL_IVB(pipe)	((pipe)<<29)
 #define  PF_FILTER_MASK		(3<<23)
 #define  PF_FILTER_PROGRAMMED	(0<<23)
 #define  PF_FILTER_MED_3x3	(1<<23)

drivers/gpu/drm/i915/intel_display.c

@@ -3387,7 +3387,11 @@ static void ironlake_crtc_enable(struct drm_crtc *crtc)
 		 * as some pre-programmed values are broken,
 		 * e.g. x201.
 		 */
-		I915_WRITE(PF_CTL(pipe), PF_ENABLE | PF_FILTER_MED_3x3);
+		if (IS_IVYBRIDGE(dev))
+			I915_WRITE(PF_CTL(pipe), PF_ENABLE | PF_FILTER_MED_3x3 |
+						 PF_PIPE_SEL_IVB(pipe));
+		else
+			I915_WRITE(PF_CTL(pipe), PF_ENABLE | PF_FILTER_MED_3x3);
 		I915_WRITE(PF_WIN_POS(pipe), dev_priv->pch_pf_pos);
 		I915_WRITE(PF_WIN_SZ(pipe), dev_priv->pch_pf_size);
 	}