media: v4l2-subdev: Limit the number of active routes to V4L2_FRAME_DESC_ENTRY_MAX

Drivers that implement routing need to report a frame descriptor
accordingly, with up to one entry per route. The number of frame
descriptor entries is fixed to V4L2_FRAME_DESC_ENTRY_MAX, currently
equal to 8. Multiple drivers therefore limit the number of routes to
V4L2_FRAME_DESC_ENTRY_MAX, with a note indicating that the limit should
be lifted when frame descriptor entries will be allocated dynamically.

Duplicating the check in multiple drivers isn't ideal. Move it to the
VIDIOC_SUBDEV_S_ROUTING handling code in the v4l2-subdev core.

Signed-off-by: Laurent Pinchart <[email protected]>
Reviewed-by: Jacopo Mondi <[email protected]>
Reviewed-by: Tomi Valkeinen <[email protected]>
Reviewed-by: Lad Prabhakar <[email protected]>
Signed-off-by: Sakari Ailus <[email protected]>
Signed-off-by: Hans Verkuil <[email protected]>

1 files changed, 14 insertions, 0 deletions

diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
index a3074f469b15..c69d1aff701f 100644
--- a/drivers/media/v4l2-core/v4l2-subdev.c
+++ b/drivers/media/v4l2-core/v4l2-subdev.c
@@ -1004,6 +1004,7 @@ static long subdev_do_ioctl(struct file *file, unsigned int cmd, void *arg,
 		struct v4l2_subdev_route *routes =
 			(struct v4l2_subdev_route *)(uintptr_t)routing->routes;
 		struct v4l2_subdev_krouting krouting = {};
+		unsigned int num_active_routes = 0;
 		unsigned int i;
 
 		if (!v4l2_subdev_enable_streams_api)
@@ -1041,9 +1042,22 @@ static long subdev_do_ioctl(struct file *file, unsigned int cmd, void *arg,
 			if (!(pads[route->source_pad].flags &
 			      MEDIA_PAD_FL_SOURCE))
 				return -EINVAL;
+
+			if (route->flags & V4L2_SUBDEV_ROUTE_FL_ACTIVE)
+				num_active_routes++;
 		}
 
 		/*
+		 * Drivers that implement routing need to report a frame
+		 * descriptor accordingly, with up to one entry per route. Until
+		 * the frame descriptors entries get allocated dynamically,
+		 * limit the number of active routes to
+		 * V4L2_FRAME_DESC_ENTRY_MAX.
+		 */
+		if (num_active_routes > V4L2_FRAME_DESC_ENTRY_MAX)
+			return -E2BIG;
+
+		/*
 		 * If the driver doesn't support setting routing, just return
 		 * the routing table.
 		 */