drm/i915: Standardize port type for DVO encoders

Changing the return type from 'char' to 'enum port' in
intel_dvo_port_name() makes it easier to later move the port information to
intel_encoder. In addition, the port type conforms to what we have
elsewhere.

Removing the last conditional that handles invalid port because dvo_reg is
intialized to valid values for all DVO devices at definition.

v2: Changed return type, for real (Jani)
Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Reviewed-by: Lyude <cpaul@redhat.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1474334681-22690-2-git-send-email-dhinakaran.pandiyan@intel.com

drivers/gpu/drm/i915/intel_dvo.c

@@ -412,16 +412,14 @@ intel_dvo_get_current_mode(struct drm_connector *connector)
 	return mode;
 }
 
-static char intel_dvo_port_name(i915_reg_t dvo_reg)
+static enum port intel_dvo_port(i915_reg_t dvo_reg)
 {
 	if (i915_mmio_reg_equal(dvo_reg, DVOA))
-		return 'A';
+		return PORT_A;
 	else if (i915_mmio_reg_equal(dvo_reg, DVOB))
-		return 'B';
-	else if (i915_mmio_reg_equal(dvo_reg, DVOC))
-		return 'C';
+		return PORT_B;
 	else
-		return '?';
+		return PORT_C;
 }
 
 void intel_dvo_init(struct drm_device *dev)
@@ -464,6 +462,7 @@ void intel_dvo_init(struct drm_device *dev)
 		bool dvoinit;
 		enum pipe pipe;
 		uint32_t dpll[I915_MAX_PIPES];
+		enum port port;
 
 		/* Allow the I2C driver info to specify the GPIO to be used in
 		 * special cases, but otherwise default to what's defined
@@ -511,9 +510,10 @@ void intel_dvo_init(struct drm_device *dev)
 		if (!dvoinit)
 			continue;
 
+		port = intel_dvo_port(dvo->dvo_reg);
 		drm_encoder_init(dev, &intel_encoder->base,
 				 &intel_dvo_enc_funcs, encoder_type,
-				 "DVO %c", intel_dvo_port_name(dvo->dvo_reg));
+				 "DVO %c", port_name(port));
 
 		intel_encoder->type = INTEL_OUTPUT_DVO;
 		intel_encoder->crtc_mask = (1 << 0) | (1 << 1);