drm/atomic: Add support for custom scaling mode properties, v2

Some connectors may not allow all scaling mode properties, this function will allow
creating the scaling mode property with only the supported subset. It also wires up
this state for atomic.

This will make it possible to convert i915 connectors to atomic.

Changes since v1:
 - Add DRM_MODE_PROP_ENUM flag to drm_property_create
 - Use the correct index in drm_property_add_enum.
 - Add DocBook for function (Sean Paul).
 - Warn if less than 2 valid scaling modes are passed.
 - Remove level of indent. (Sean Paul)

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170501133804.8116-3-maarten.lankhorst@linux.intel.com
[mlankhorst: Rename function, fix docbook issues]
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 64 insertions, 0 deletions

diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
index 9f847615ac74..5cd61aff7857 100644
--- a/drivers/gpu/drm/drm_connector.c
+++ b/drivers/gpu/drm/drm_connector.c
@@ -941,6 +941,10 @@ EXPORT_SYMBOL(drm_mode_create_tv_properties);
  *
  * Called by a driver the first time it's needed, must be attached to desired
  * connectors.
+ *
+ * Atomic drivers should use drm_connector_attach_scaling_mode_property()
+ * instead to correctly assign &drm_connector_state.picture_aspect_ratio
+ * in the atomic state.
  */
 int drm_mode_create_scaling_mode_property(struct drm_device *dev)
 {
@@ -961,6 +965,66 @@ int drm_mode_create_scaling_mode_property(struct drm_device *dev)
 EXPORT_SYMBOL(drm_mode_create_scaling_mode_property);
 
 /**
+ * drm_connector_attach_scaling_mode_property - attach atomic scaling mode property
+ * @connector: connector to attach scaling mode property on.
+ * @scaling_mode_mask: or'ed mask of BIT(%DRM_MODE_SCALE_\*).
+ *
+ * This is used to add support for scaling mode to atomic drivers.
+ * The scaling mode will be set to &drm_connector_state.picture_aspect_ratio
+ * and can be used from &drm_connector_helper_funcs->atomic_check for validation.
+ *
+ * This is the atomic version of drm_mode_create_scaling_mode_property().
+ *
+ * Returns:
+ * Zero on success, negative errno on failure.
+ */
+int drm_connector_attach_scaling_mode_property(struct drm_connector *connector,
+					       u32 scaling_mode_mask)
+{
+	struct drm_device *dev = connector->dev;
+	struct drm_property *scaling_mode_property;
+	int i, j = 0;
+	const unsigned valid_scaling_mode_mask =
+		(1U << ARRAY_SIZE(drm_scaling_mode_enum_list)) - 1;
+
+	if (WARN_ON(hweight32(scaling_mode_mask) < 2 ||
+		    scaling_mode_mask & ~valid_scaling_mode_mask))
+		return -EINVAL;
+
+	scaling_mode_property =
+		drm_property_create(dev, DRM_MODE_PROP_ENUM, "scaling mode",
+				    hweight32(scaling_mode_mask));
+
+	if (!scaling_mode_property)
+		return -ENOMEM;
+
+	for (i = 0; i < ARRAY_SIZE(drm_scaling_mode_enum_list); i++) {
+		int ret;
+
+		if (!(BIT(i) & scaling_mode_mask))
+			continue;
+
+		ret = drm_property_add_enum(scaling_mode_property, j++,
+					    drm_scaling_mode_enum_list[i].type,
+					    drm_scaling_mode_enum_list[i].name);
+
+		if (ret) {
+			drm_property_destroy(dev, scaling_mode_property);
+
+			return ret;
+		}
+	}
+
+	drm_object_attach_property(&connector->base,
+				   scaling_mode_property, 0);
+
+	connector->scaling_mode_property = scaling_mode_property;
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_connector_attach_scaling_mode_property);
+
+/**
  * drm_mode_create_aspect_ratio_property - create aspect ratio property
  * @dev: DRM device
  *