[RFC] drm: store property instead of id in obj attachment

[Rob Clark]

Keep property pointer, instead of id, in per mode-object attachments.
This will simplify things in later patches.

---
Does anyone care about the lifetime issue and dangling property ptrs?
Currently properties are destroyed during drm_mode_config_cleanup(),
so it doesn't really matter.. if someone *did* see a use for dynamically
destroying properties we'd have to do something a bit more clever and
handle properly detaching from any mode object to which that property
had been attached.

Just sending as an RFC for now, but later atomic properties/ioctl patches
will depend on this.

 drivers/gpu/drm/drm_crtc.c | 17 ++++++++---------
 include/drm/drm_crtc.h     |  7 ++++++-
 2 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index 3ba84df..3e6ef39 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -2058,12 +2058,11 @@ int drm_mode_getconnector(struct drm_device *dev, void *data,
 		prop_ptr = (uint32_t __user *)(unsigned long)(out_resp->props_ptr);
 		prop_values = (uint64_t __user *)(unsigned long)(out_resp->prop_values_ptr);
 		for (i = 0; i < connector->properties.count; i++) {
-			if (put_user(connector->properties.ids[i],
-				     prop_ptr + copied)) {
+			struct drm_property *prop = connector->properties.properties[i];
+			if (put_user(prop->base.id, prop_ptr + copied)) {
 				ret = -EFAULT;
 				goto out;
 			}
-
 			if (put_user(connector->properties.values[i],
 				     prop_values + copied)) {
 				ret = -EFAULT;
@@ -3744,7 +3743,7 @@ void drm_object_attach_property(struct drm_mode_object *obj,
 		return;
 	}
 
-	obj->properties->ids[count] = property->base.id;
+	obj->properties->properties[count] = property;
 	obj->properties->values[count] = init_val;
 	obj->properties->count++;
 }
@@ -3769,7 +3768,7 @@ int drm_object_property_set_value(struct drm_mode_object *obj,
 	int i;
 
 	for (i = 0; i < obj->properties->count; i++) {
-		if (obj->properties->ids[i] == property->base.id) {
+		if (obj->properties->properties[i] == property) {
 			obj->properties->values[i] = val;
 			return 0;
 		}
@@ -3799,7 +3798,7 @@ int drm_object_property_get_value(struct drm_mode_object *obj,
 	int i;
 
 	for (i = 0; i < obj->properties->count; i++) {
-		if (obj->properties->ids[i] == property->base.id) {
+		if (obj->properties->properties[i] == property) {
 			*val = obj->properties->values[i];
 			return 0;
 		}
@@ -4263,8 +4262,8 @@ int drm_mode_obj_get_properties_ioctl(struct drm_device *dev, void *data,
 		prop_values_ptr = (uint64_t __user *)(unsigned long)
 				  (arg->prop_values_ptr);
 		for (i = 0; i < props_count; i++) {
-			if (put_user(obj->properties->ids[i],
-				     props_ptr + copied)) {
+			struct drm_property *prop = obj->properties->properties[i];
+			if (put_user(prop->base.id, props_ptr + copied)) {
 				ret = -EFAULT;
 				goto out;
 			}
@@ -4322,7 +4321,7 @@ int drm_mode_obj_set_property_ioctl(struct drm_device *dev, void *data,
 		goto out;
 
 	for (i = 0; i < arg_obj->properties->count; i++)
-		if (arg_obj->properties->ids[i] == arg->prop_id)
+		if (arg_obj->properties->properties[i]->base.id == arg->prop_id)
 			break;
 
 	if (i == arg_obj->properties->count)
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index dd2c16e..017029d 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -64,7 +64,12 @@ struct drm_mode_object {
 #define DRM_OBJECT_MAX_PROPERTY 24
 struct drm_object_properties {
 	int count;
-	uint32_t ids[DRM_OBJECT_MAX_PROPERTY];
+	/* NOTE: if we ever start dynamically destroying properties (ie.
+	 * not at drm_mode_config_cleanup() time), then we'd have to do
+	 * a better job of detaching property from mode objects to avoid
+	 * dangling property pointers:
+	 */
+	struct drm_property *properties[DRM_OBJECT_MAX_PROPERTY];
 	uint64_t values[DRM_OBJECT_MAX_PROPERTY];
 };
 
-- 
1.9.3