drm/crtc: Add property for aspect ratio

Added a property to enable user space to set aspect ratio.
This patch contains declaration of the property and code to create the
property.

v2: Thierry's review comments.
	- Made aspect ratio enum generic instead of HDMI/CEA specfic
	- Removed usage of temporary aspect_ratio variable

v3: Thierry's review comments.
	- Fixed indentation

v4: Thierry's review comments.
	- Return ENOMEM when property creation fails
Signed-off-by: Vandana Kannan <vandana.kannan@intel.com>
Cc: Thierry Reding <thierry.reding@gmail.com>
Reviewed-by: Thierry Reding <treding@nvidia.com>
Acked-by: Dave Airlie <airlied@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/drm_crtc.c

@@ -182,6 +182,12 @@ static const struct drm_prop_enum_list drm_scaling_mode_enum_list[] =
 	{ DRM_MODE_SCALE_ASPECT, "Full aspect" },
 };
 
+static const struct drm_prop_enum_list drm_aspect_ratio_enum_list[] = {
+	{ DRM_MODE_PICTURE_ASPECT_NONE, "Automatic" },
+	{ DRM_MODE_PICTURE_ASPECT_4_3, "4:3" },
+	{ DRM_MODE_PICTURE_ASPECT_16_9, "16:9" },
+};
+
 /*
  * Non-global properties, but "required" for certain connectors.
  */
@@ -1390,6 +1396,33 @@ int drm_mode_create_scaling_mode_property(struct drm_device *dev)
 }
 EXPORT_SYMBOL(drm_mode_create_scaling_mode_property);
 
+/**
+ * drm_mode_create_aspect_ratio_property - create aspect ratio property
+ * @dev: DRM device
+ *
+ * Called by a driver the first time it's needed, must be attached to desired
+ * connectors.
+ *
+ * Returns:
+ * Zero on success, errno on failure.
+ */
+int drm_mode_create_aspect_ratio_property(struct drm_device *dev)
+{
+	if (dev->mode_config.aspect_ratio_property)
+		return 0;
+
+	dev->mode_config.aspect_ratio_property =
+		drm_property_create_enum(dev, 0, "aspect ratio",
+				drm_aspect_ratio_enum_list,
+				ARRAY_SIZE(drm_aspect_ratio_enum_list));
+
+	if (dev->mode_config.aspect_ratio_property == NULL)
+		return -ENOMEM;
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_mode_create_aspect_ratio_property);
+
 /**
  * drm_mode_create_dirty_property - create dirty property
  * @dev: DRM device

include/drm/drm_crtc.h

@@ -835,6 +835,7 @@ struct drm_mode_config {
 
 	/* Optional properties */
 	struct drm_property *scaling_mode_property;
+	struct drm_property *aspect_ratio_property;
 	struct drm_property *dirty_info_property;
 
 	/* dumb ioctl parameters */
@@ -1023,6 +1024,7 @@ extern int drm_mode_create_dvi_i_properties(struct drm_device *dev);
 extern int drm_mode_create_tv_properties(struct drm_device *dev, int num_formats,
 				     char *formats[]);
 extern int drm_mode_create_scaling_mode_property(struct drm_device *dev);
+extern int drm_mode_create_aspect_ratio_property(struct drm_device *dev);
 extern int drm_mode_create_dirty_info_property(struct drm_device *dev);
 
 extern int drm_mode_connector_attach_encoder(struct drm_connector *connector,

include/uapi/drm/drm_mode.h

@@ -88,6 +88,11 @@
 #define DRM_MODE_SCALE_CENTER		2 /* Centered, no scaling */
 #define DRM_MODE_SCALE_ASPECT		3 /* Full screen, preserve aspect */
 
+/* Picture aspect ratio options */
+#define DRM_MODE_PICTURE_ASPECT_NONE	0
+#define DRM_MODE_PICTURE_ASPECT_4_3	1
+#define DRM_MODE_PICTURE_ASPECT_16_9	2
+
 /* Dithering mode options */
 #define DRM_MODE_DITHERING_OFF	0
 #define DRM_MODE_DITHERING_ON	1