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Subject: [PATCH v2 1/2] drm/atomic: Allow drivers to write their own plane check for async flips
Date: Fri, 19 Jan 2024 15:12:34 -0300
Message-ID: <20240119181235.255060-2-andrealmeid@igalia.com>
In-Reply-To: <20240119181235.255060-1-andrealmeid@igalia.com>
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Some hardware are more flexible on what they can flip asynchronously, so
rework the plane check so drivers can implement their own check, lifting
up some of the restrictions.

Signed-off-by: André Almeida <andrealmeid@igalia.com>
---
 drivers/gpu/drm/drm_atomic_uapi.c | 62 ++++++++++++++++++++++---------
 include/drm/drm_atomic_uapi.h     | 12 ++++++
 include/drm/drm_plane.h           |  5 +++
 3 files changed, 62 insertions(+), 17 deletions(-)

diff --git a/drivers/gpu/drm/drm_atomic_uapi.c b/drivers/gpu/drm/drm_atomic_uapi.c
index aee4a65d4959..6d5b9fec90c7 100644
--- a/drivers/gpu/drm/drm_atomic_uapi.c
+++ b/drivers/gpu/drm/drm_atomic_uapi.c
@@ -620,7 +620,7 @@ static int drm_atomic_plane_set_property(struct drm_plane *plane,
 	return 0;
 }
 
-static int
+int
 drm_atomic_plane_get_property(struct drm_plane *plane,
 		const struct drm_plane_state *state,
 		struct drm_property *property, uint64_t *val)
@@ -683,6 +683,7 @@ drm_atomic_plane_get_property(struct drm_plane *plane,
 
 	return 0;
 }
+EXPORT_SYMBOL(drm_atomic_plane_get_property);
 
 static int drm_atomic_set_writeback_fb_for_connector(
 		struct drm_connector_state *conn_state,
@@ -1026,18 +1027,54 @@ int drm_atomic_connector_commit_dpms(struct drm_atomic_state *state,
 	return ret;
 }
 
-static int drm_atomic_check_prop_changes(int ret, uint64_t old_val, uint64_t prop_value,
+int drm_atomic_check_prop_changes(int ret, uint64_t old_val, uint64_t prop_value,
 					 struct drm_property *prop)
 {
 	if (ret != 0 || old_val != prop_value) {
 		drm_dbg_atomic(prop->dev,
-			       "[PROP:%d:%s] No prop can be changed during async flip\n",
+			       "[PROP:%d:%s] This prop cannot be changed during async flip\n",
 			       prop->base.id, prop->name);
 		return -EINVAL;
 	}
 
 	return 0;
 }
+EXPORT_SYMBOL(drm_atomic_check_prop_changes);
+
+/* plane changes may have exceptions, so we have a special function for them */
+static int drm_atomic_check_plane_changes(struct drm_property *prop,
+					  struct drm_plane *plane,
+					  struct drm_plane_state *plane_state,
+					  struct drm_mode_object *obj,
+					  u64 prop_value, u64 old_val)
+{
+	struct drm_mode_config *config = &plane->dev->mode_config;
+	int ret;
+
+	if (plane->funcs->check_async_props)
+		return plane->funcs->check_async_props(prop, plane, plane_state,
+							     obj, prop_value, old_val);
+
+	/*
+	 * if you are trying to change something other than the FB ID, your
+	 * change will be either rejected or ignored, so we can stop the check
+	 * here
+	 */
+	if (prop != config->prop_fb_id) {
+		ret = drm_atomic_plane_get_property(plane, plane_state,
+						    prop, &old_val);
+		return drm_atomic_check_prop_changes(ret, old_val, prop_value, prop);
+	}
+
+	if (plane_state->plane->type != DRM_PLANE_TYPE_PRIMARY) {
+		drm_dbg_atomic(prop->dev,
+			       "[OBJECT:%d] Only primary planes can be changed during async flip\n",
+			       obj->id);
+		return -EINVAL;
+	}
+
+	return 0;
+}
 
 int drm_atomic_set_property(struct drm_atomic_state *state,
 			    struct drm_file *file_priv,
@@ -1100,7 +1137,6 @@ int drm_atomic_set_property(struct drm_atomic_state *state,
 	case DRM_MODE_OBJECT_PLANE: {
 		struct drm_plane *plane = obj_to_plane(obj);
 		struct drm_plane_state *plane_state;
-		struct drm_mode_config *config = &plane->dev->mode_config;
 
 		plane_state = drm_atomic_get_plane_state(state, plane);
 		if (IS_ERR(plane_state)) {
@@ -1108,19 +1144,11 @@ int drm_atomic_set_property(struct drm_atomic_state *state,
 			break;
 		}
 
-		if (async_flip && prop != config->prop_fb_id) {
-			ret = drm_atomic_plane_get_property(plane, plane_state,
-							    prop, &old_val);
-			ret = drm_atomic_check_prop_changes(ret, old_val, prop_value, prop);
-			break;
-		}
-
-		if (async_flip && plane_state->plane->type != DRM_PLANE_TYPE_PRIMARY) {
-			drm_dbg_atomic(prop->dev,
-				       "[OBJECT:%d] Only primary planes can be changed during async flip\n",
-				       obj->id);
-			ret = -EINVAL;
-			break;
+		if (async_flip) {
+			ret = drm_atomic_check_plane_changes(prop, plane, plane_state,
+							     obj, prop_value, old_val);
+			if (ret)
+				break;
 		}
 
 		ret = drm_atomic_plane_set_property(plane,
diff --git a/include/drm/drm_atomic_uapi.h b/include/drm/drm_atomic_uapi.h
index 4c6d39d7bdb2..d65fa8fbbca0 100644
--- a/include/drm/drm_atomic_uapi.h
+++ b/include/drm/drm_atomic_uapi.h
@@ -29,6 +29,8 @@
 #ifndef DRM_ATOMIC_UAPI_H_
 #define DRM_ATOMIC_UAPI_H_
 
+#include <linux/types.h>
+
 struct drm_crtc_state;
 struct drm_display_mode;
 struct drm_property_blob;
@@ -37,6 +39,9 @@ struct drm_crtc;
 struct drm_connector_state;
 struct dma_fence;
 struct drm_framebuffer;
+struct drm_mode_object;
+struct drm_property;
+struct drm_plane;
 
 int __must_check
 drm_atomic_set_mode_for_crtc(struct drm_crtc_state *state,
@@ -53,4 +58,11 @@ int __must_check
 drm_atomic_set_crtc_for_connector(struct drm_connector_state *conn_state,
 				  struct drm_crtc *crtc);
 
+int drm_atomic_plane_get_property(struct drm_plane *plane,
+				  const struct drm_plane_state *state,
+				  struct drm_property *property, uint64_t *val);
+
+int drm_atomic_check_prop_changes(int ret, uint64_t old_val, uint64_t prop_value,
+				  struct drm_property *prop);
+
 #endif
diff --git a/include/drm/drm_plane.h b/include/drm/drm_plane.h
index c6565a6f9324..73dac8d76831 100644
--- a/include/drm/drm_plane.h
+++ b/include/drm/drm_plane.h
@@ -540,6 +540,11 @@ struct drm_plane_funcs {
 	 */
 	bool (*format_mod_supported)(struct drm_plane *plane, uint32_t format,
 				     uint64_t modifier);
+
+	int (*check_async_props)(struct drm_property *prop, struct drm_plane *plane,
+				 struct drm_plane_state *plane_state,
+				 struct drm_mode_object *obj,
+				 u64 prop_value, u64 old_val);
 };
 
 /**
-- 
2.43.0