media: subdev: Add V4L2_SUBDEV_ROUTING_NO_MULTIPLEXING

A common case with subdev routing is that on the subdevice just before
the DMA engines (video nodes), no multiplexing is allowed on the source
pads, as the DMA engine can only handle a single stream.

In some other situations one might also want to do the same check on the
sink side.

Add new routing validation flags to check these:
V4L2_SUBDEV_ROUTING_NO_SINK_MULTIPLEXING and
V4L2_SUBDEV_ROUTING_NO_SOURCE_MULTIPLEXING.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

drivers/media/v4l2-core/v4l2-subdev.c

@@ -1708,7 +1708,8 @@ int v4l2_subdev_routing_validate(struct v4l2_subdev *sd,
 	unsigned int i, j;
 	int ret = -EINVAL;
 
-	if (disallow & V4L2_SUBDEV_ROUTING_NO_STREAM_MIX) {
+	if (disallow & (V4L2_SUBDEV_ROUTING_NO_STREAM_MIX |
+			V4L2_SUBDEV_ROUTING_NO_MULTIPLEXING)) {
 		remote_pads = kcalloc(sd->entity.num_pads, sizeof(*remote_pads),
 				      GFP_KERNEL);
 		if (!remote_pads)
@@ -1748,8 +1749,6 @@ int v4l2_subdev_routing_validate(struct v4l2_subdev *sd,
 					i, "sink");
 				goto out;
 			}
-
-			remote_pads[route->sink_pad] = route->source_pad;
 		}
 
 		/*
@@ -1764,7 +1763,38 @@ int v4l2_subdev_routing_validate(struct v4l2_subdev *sd,
 					i, "source");
 				goto out;
 			}
+		}
+
+		/*
+		 * V4L2_SUBDEV_ROUTING_NO_SINK_MULTIPLEXING: Pads on the sink
+		 * side can not do stream multiplexing, i.e. there can be only
+		 * a single stream in a sink pad.
+		 */
+		if (disallow & V4L2_SUBDEV_ROUTING_NO_SINK_MULTIPLEXING) {
+			if (remote_pads[route->sink_pad] != U32_MAX) {
+				dev_dbg(sd->dev,
+					"route %u attempts to multiplex on %s pad %u\n",
+					i, "sink", route->sink_pad);
+				goto out;
+			}
+		}
 
+		/*
+		 * V4L2_SUBDEV_ROUTING_NO_SOURCE_MULTIPLEXING: Pads on the
+		 * source side can not do stream multiplexing, i.e. there can
+		 * be only a single stream in a source pad.
+		 */
+		if (disallow & V4L2_SUBDEV_ROUTING_NO_SOURCE_MULTIPLEXING) {
+			if (remote_pads[route->source_pad] != U32_MAX) {
+				dev_dbg(sd->dev,
+					"route %u attempts to multiplex on %s pad %u\n",
+					i, "source", route->source_pad);
+				goto out;
+			}
+		}
+
+		if (remote_pads) {
+			remote_pads[route->sink_pad] = route->source_pad;
 			remote_pads[route->source_pad] = route->sink_pad;
 		}
 

include/media/v4l2-subdev.h

@@ -1651,6 +1651,10 @@ u64 v4l2_subdev_state_xlate_streams(const struct v4l2_subdev_state *state,
  *	all streams from a sink pad must be routed to a single source pad
  * @V4L2_SUBDEV_ROUTING_NO_SOURCE_STREAM_MIX:
  *	all streams on a source pad must originate from a single sink pad
+ * @V4L2_SUBDEV_ROUTING_NO_SOURCE_MULTIPLEXING:
+ *	source pads shall not contain multiplexed streams
+ * @V4L2_SUBDEV_ROUTING_NO_SINK_MULTIPLEXING:
+ *	sink pads shall not contain multiplexed streams
  * @V4L2_SUBDEV_ROUTING_ONLY_1_TO_1:
  *	only non-overlapping 1-to-1 stream routing is allowed (a combination of
  *	@V4L2_SUBDEV_ROUTING_NO_1_TO_N and @V4L2_SUBDEV_ROUTING_NO_N_TO_1)
@@ -1659,18 +1663,25 @@ u64 v4l2_subdev_state_xlate_streams(const struct v4l2_subdev_state *state,
  *	that source pad shall not get routes from any other sink pad
  *	(a combination of @V4L2_SUBDEV_ROUTING_NO_SINK_STREAM_MIX and
  *	@V4L2_SUBDEV_ROUTING_NO_SOURCE_STREAM_MIX)
+ * @V4L2_SUBDEV_ROUTING_NO_MULTIPLEXING:
+ *	no multiplexed streams allowed on either source or sink sides.
  */
 enum v4l2_subdev_routing_restriction {
 	V4L2_SUBDEV_ROUTING_NO_1_TO_N = BIT(0),
 	V4L2_SUBDEV_ROUTING_NO_N_TO_1 = BIT(1),
 	V4L2_SUBDEV_ROUTING_NO_SINK_STREAM_MIX = BIT(2),
 	V4L2_SUBDEV_ROUTING_NO_SOURCE_STREAM_MIX = BIT(3),
+	V4L2_SUBDEV_ROUTING_NO_SINK_MULTIPLEXING = BIT(4),
+	V4L2_SUBDEV_ROUTING_NO_SOURCE_MULTIPLEXING = BIT(5),
 	V4L2_SUBDEV_ROUTING_ONLY_1_TO_1 =
 		V4L2_SUBDEV_ROUTING_NO_1_TO_N |
 		V4L2_SUBDEV_ROUTING_NO_N_TO_1,
 	V4L2_SUBDEV_ROUTING_NO_STREAM_MIX =
 		V4L2_SUBDEV_ROUTING_NO_SINK_STREAM_MIX |
 		V4L2_SUBDEV_ROUTING_NO_SOURCE_STREAM_MIX,
+	V4L2_SUBDEV_ROUTING_NO_MULTIPLEXING =
+		V4L2_SUBDEV_ROUTING_NO_SINK_MULTIPLEXING |
+		V4L2_SUBDEV_ROUTING_NO_SOURCE_MULTIPLEXING,
 };
 
 /**