drm/i915: add for_each_port() and use it

Add another for_each style macro to the pile of custom looping macros.
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191101134333.11612-1-jani.nikula@intel.com

drivers/gpu/drm/i915/display/intel_bios.c

@@ -1246,7 +1246,7 @@ static enum port get_port_by_ddc_pin(struct drm_i915_private *i915, u8 ddc_pin)
 	const struct ddi_vbt_port_info *info;
 	enum port port;
 
-	for (port = PORT_A; port < I915_MAX_PORTS; port++) {
+	for_each_port(port) {
 		info = &i915->vbt.ddi_port_info[port];
 
 		if (info->child && ddc_pin == info->alternate_ddc_pin)
@@ -1297,7 +1297,7 @@ static enum port get_port_by_aux_ch(struct drm_i915_private *i915, u8 aux_ch)
 	const struct ddi_vbt_port_info *info;
 	enum port port;
 
-	for (port = PORT_A; port < I915_MAX_PORTS; port++) {
+	for_each_port(port) {
 		info = &i915->vbt.ddi_port_info[port];
 
 		if (info->child && aux_ch == info->alternate_aux_channel)
@@ -1722,7 +1722,7 @@ init_vbt_defaults(struct drm_i915_private *dev_priv)
 			!HAS_PCH_SPLIT(dev_priv));
 	DRM_DEBUG_KMS("Set default to SSC at %d kHz\n", dev_priv->vbt.lvds_ssc_freq);
 
-	for (port = PORT_A; port < I915_MAX_PORTS; port++) {
+	for_each_port(port) {
 		struct ddi_vbt_port_info *info =
 			&dev_priv->vbt.ddi_port_info[port];
 
@@ -1736,7 +1736,7 @@ init_vbt_missing_defaults(struct drm_i915_private *dev_priv)
 {
 	enum port port;
 
-	for (port = PORT_A; port < I915_MAX_PORTS; port++) {
+	for_each_port(port) {
 		struct ddi_vbt_port_info *info =
 			&dev_priv->vbt.ddi_port_info[port];
 		enum phy phy = intel_port_to_phy(dev_priv, port);

drivers/gpu/drm/i915/display/intel_display.h

@@ -333,8 +333,11 @@ enum phy_fia {
 	     (__s) < RUNTIME_INFO(__dev_priv)->num_sprites[(__p)];	\
 	     (__s)++)
 
+#define for_each_port(__port) \
+	for ((__port) = PORT_A; (__port) < I915_MAX_PORTS; (__port)++)
+
 #define for_each_port_masked(__port, __ports_mask)			\
-	for ((__port) = PORT_A; (__port) < I915_MAX_PORTS; (__port)++)	\
+	for_each_port(__port)						\
 		for_each_if((__ports_mask) & BIT(__port))
 
 #define for_each_phy_masked(__phy, __phys_mask) \