drm/object: Add drm_object_property_get_default_value() function

Some functions to create properties (drm_plane_create_zpos_property or
drm_plane_create_color_properties for example) will ask for a range of
acceptable value and an initial one.

This initial value is then stored in the values array for that property.

Let's provide an helper to access this property.

Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20220221095918.18763-7-maxime@cerno.tech

diff --git a/drivers/gpu/drm/drm_mode_object.c b/drivers/gpu/drm/drm_mode_object.c
index 86d9e90..ba1608e 100644 (file)
--- a/drivers/gpu/drm/drm_mode_object.c
+++ b/drivers/gpu/drm/drm_mode_object.c
@@ -297,11 +297,26 @@ int drm_object_property_set_value(struct drm_mode_object *obj,
 }
 EXPORT_SYMBOL(drm_object_property_set_value);
 
+static int __drm_object_property_get_prop_value(struct drm_mode_object *obj,
+                                               struct drm_property *property,
+                                               uint64_t *val)
+{
+       int i;
+
+       for (i = 0; i < obj->properties->count; i++) {
+               if (obj->properties->properties[i] == property) {
+                       *val = obj->properties->values[i];
+                       return 0;
+               }
+       }
+
+       return -EINVAL;
+}
+
 static int __drm_object_property_get_value(struct drm_mode_object *obj,
                                           struct drm_property *property,
                                           uint64_t *val)
 {
-       int i;
 
        /* read-only properties bypass atomic mechanism and still store
         * their value in obj->properties->values[].. mostly to avoid
@@ -311,15 +326,7 @@ static int __drm_object_property_get_value(struct drm_mode_object *obj,
                        !(property->flags & DRM_MODE_PROP_IMMUTABLE))
                return drm_atomic_get_property(obj, property, val);
 
-       for (i = 0; i < obj->properties->count; i++) {
-               if (obj->properties->properties[i] == property) {
-                       *val = obj->properties->values[i];
-                       return 0;
-               }
-
-       }
-
-       return -EINVAL;
+       return __drm_object_property_get_prop_value(obj, property, val);
 }
 
 /**
@@ -348,6 +355,32 @@ int drm_object_property_get_value(struct drm_mode_object *obj,
 }
 EXPORT_SYMBOL(drm_object_property_get_value);
 
+/**
+ * drm_object_property_get_default_value - retrieve the default value of a
+ * property when in atomic mode.
+ * @obj: drm mode object to get property value from
+ * @property: property to retrieve
+ * @val: storage for the property value
+ *
+ * This function retrieves the default state of the given property as passed in
+ * to drm_object_attach_property
+ *
+ * Only atomic drivers should call this function directly, as for non-atomic
+ * drivers it will return the current value.
+ *
+ * Returns:
+ * Zero on success, error code on failure.
+ */
+int drm_object_property_get_default_value(struct drm_mode_object *obj,
+                                         struct drm_property *property,
+                                         uint64_t *val)
+{
+       WARN_ON(!drm_drv_uses_atomic_modeset(property->dev));
+
+       return __drm_object_property_get_prop_value(obj, property, val);
+}
+EXPORT_SYMBOL(drm_object_property_get_default_value);
+
 /* helper for getconnector and getproperties ioctls */
 int drm_mode_object_get_properties(struct drm_mode_object *obj, bool atomic,
                                   uint32_t __user *prop_ptr,

diff --git a/include/drm/drm_mode_object.h b/include/drm/drm_mode_object.h
index c34a3e8..912f1e4 100644 (file)
--- a/include/drm/drm_mode_object.h
+++ b/include/drm/drm_mode_object.h
@@ -98,6 +98,10 @@ struct drm_object_properties {
         * Hence atomic drivers should not use drm_object_property_set_value()
         * and drm_object_property_get_value() on mutable objects, i.e. those
         * without the DRM_MODE_PROP_IMMUTABLE flag set.
+        *
+        * For atomic drivers the default value of properties is stored in this
+        * array, so drm_object_property_get_default_value can be used to
+        * retrieve it.
         */
        uint64_t values[DRM_OBJECT_MAX_PROPERTY];
 };
@@ -126,6 +130,9 @@ int drm_object_property_set_value(struct drm_mode_object *obj,
 int drm_object_property_get_value(struct drm_mode_object *obj,
                                  struct drm_property *property,
                                  uint64_t *value);
+int drm_object_property_get_default_value(struct drm_mode_object *obj,
+                                         struct drm_property *property,
+                                         uint64_t *val);
 
 void drm_object_attach_property(struct drm_mode_object *obj,
                                struct drm_property *property,