drm/i915: fix pipe DDI mode select

Mask the value before changing it and also select DVI when needed.

DVI was working in cases where the BIOS was setting the correct value
because we were not masking the value before changing it.
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_reg.h

@@ -4302,6 +4302,7 @@
 /* Those bits are ignored by pipe EDP since it can only connect to DDI A */
 #define  PIPE_DDI_PORT_MASK			(7<<28)
 #define  PIPE_DDI_SELECT_PORT(x)		((x)<<28)
+#define  PIPE_DDI_MODE_SELECT_MASK		(7<<24)
 #define  PIPE_DDI_MODE_SELECT_HDMI		(0<<24)
 #define  PIPE_DDI_MODE_SELECT_DVI		(1<<24)
 #define  PIPE_DDI_MODE_SELECT_DP_SST	(2<<24)

drivers/gpu/drm/i915/intel_ddi.c

@@ -726,13 +726,18 @@ void intel_ddi_mode_set(struct drm_encoder *encoder,
 	temp = I915_READ(DDI_FUNC_CTL(pipe));
 	temp &= ~PIPE_DDI_PORT_MASK;
 	temp &= ~PIPE_DDI_BPC_12;
+	temp &= ~PIPE_DDI_MODE_SELECT_MASK;
 	temp |= PIPE_DDI_SELECT_PORT(port) |
-			PIPE_DDI_MODE_SELECT_HDMI |
 			((intel_crtc->bpp > 24) ?
 				PIPE_DDI_BPC_12 :
 				PIPE_DDI_BPC_8) |
 			PIPE_DDI_FUNC_ENABLE;
 
+	if (intel_hdmi->has_hdmi_sink)
+		temp |= PIPE_DDI_MODE_SELECT_HDMI;
+	else
+		temp |= PIPE_DDI_MODE_SELECT_DVI;
+
 	I915_WRITE(DDI_FUNC_CTL(pipe), temp);
 
 	intel_hdmi->set_infoframes(encoder, adjusted_mode);