drm/i915: Clean up DVO pipe select bits

Parametrize the DVO pipe select bits.

For consistency with the new way of doing things, let's read out the
pipe select bits even when the port is disable, even though we don't
need that behaviour for asserts in this case.

v2: Order the defines shift,mask,value (Jani)

Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180514172423.9302-5-ville.syrjala@linux.intel.com

drivers/gpu/drm/i915/i915_reg.h

@@ -4357,7 +4357,9 @@ enum {
 #define _DVOC			0x61160
 #define DVOC			_MMIO(_DVOC)
 #define   DVO_ENABLE			(1 << 31)
-#define   DVO_PIPE_B_SELECT		(1 << 30)
+#define   DVO_PIPE_SEL_SHIFT		30
+#define   DVO_PIPE_SEL_MASK		(1 << 30)
+#define   DVO_PIPE_SEL(pipe)		((pipe) << 30)
 #define   DVO_PIPE_STALL_UNUSED		(0 << 28)
 #define   DVO_PIPE_STALL		(1 << 28)
 #define   DVO_PIPE_STALL_TV		(2 << 28)

drivers/gpu/drm/i915/intel_dvo.c

@@ -137,19 +137,15 @@ static bool intel_dvo_connector_get_hw_state(struct intel_connector *connector)
 static bool intel_dvo_get_hw_state(struct intel_encoder *encoder,
 				   enum pipe *pipe)
 {
-	struct drm_device *dev = encoder->base.dev;
-	struct drm_i915_private *dev_priv = to_i915(dev);
+	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
 	struct intel_dvo *intel_dvo = enc_to_dvo(encoder);
 	u32 tmp;
 
 	tmp = I915_READ(intel_dvo->dev.dvo_reg);
 
-	if (!(tmp & DVO_ENABLE))
-		return false;
-
-	*pipe = PORT_TO_PIPE(tmp);
+	*pipe = (tmp & DVO_PIPE_SEL_MASK) >> DVO_PIPE_SEL_SHIFT;
 
-	return true;
+	return tmp & DVO_ENABLE;
 }
 
 static void intel_dvo_get_config(struct intel_encoder *encoder,
@@ -276,8 +272,7 @@ static void intel_dvo_pre_enable(struct intel_encoder *encoder,
 	dvo_val |= DVO_DATA_ORDER_FP | DVO_BORDER_ENABLE |
 		   DVO_BLANK_ACTIVE_HIGH;
 
-	if (pipe == 1)
-		dvo_val |= DVO_PIPE_B_SELECT;
+	dvo_val |= DVO_PIPE_SEL(pipe);
 	dvo_val |= DVO_PIPE_STALL;
 	if (adjusted_mode->flags & DRM_MODE_FLAG_PHSYNC)
 		dvo_val |= DVO_HSYNC_ACTIVE_HIGH;