drm/client: Add drm_client_framebuffer_flush()

Some drivers need explicit flushing of buffer changes, add a function
that does that.

v2:
- Put all clip rect stuff inside if statement (Sam)
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200509141619.32970-4-noralf@tronnes.org

drivers/gpu/drm/drm_client.c

@@ -437,6 +437,39 @@ void drm_client_framebuffer_delete(struct drm_client_buffer *buffer)
 }
 EXPORT_SYMBOL(drm_client_framebuffer_delete);
 
+/**
+ * drm_client_framebuffer_flush - Manually flush client framebuffer
+ * @buffer: DRM client buffer (can be NULL)
+ * @rect: Damage rectangle (if NULL flushes all)
+ *
+ * This calls &drm_framebuffer_funcs->dirty (if present) to flush buffer changes
+ * for drivers that need it.
+ *
+ * Returns:
+ * Zero on success or negative error code on failure.
+ */
+int drm_client_framebuffer_flush(struct drm_client_buffer *buffer, struct drm_rect *rect)
+{
+	if (!buffer || !buffer->fb || !buffer->fb->funcs->dirty)
+		return 0;
+
+	if (rect) {
+		struct drm_clip_rect clip = {
+			.x1 = rect->x1,
+			.y1 = rect->y1,
+			.x2 = rect->x2,
+			.y2 = rect->y2,
+		};
+
+		return buffer->fb->funcs->dirty(buffer->fb, buffer->client->file,
+						0, 0, &clip, 1);
+	}
+
+	return buffer->fb->funcs->dirty(buffer->fb, buffer->client->file,
+					0, 0, NULL, 0);
+}
+EXPORT_SYMBOL(drm_client_framebuffer_flush);
+
 #ifdef CONFIG_DEBUG_FS
 static int drm_client_debugfs_internal_clients(struct seq_file *m, void *data)
 {

include/drm/drm_client.h

@@ -154,6 +154,7 @@ struct drm_client_buffer {
 struct drm_client_buffer *
 drm_client_framebuffer_create(struct drm_client_dev *client, u32 width, u32 height, u32 format);
 void drm_client_framebuffer_delete(struct drm_client_buffer *buffer);
+int drm_client_framebuffer_flush(struct drm_client_buffer *buffer, struct drm_rect *rect);
 void *drm_client_buffer_vmap(struct drm_client_buffer *buffer);
 void drm_client_buffer_vunmap(struct drm_client_buffer *buffer);