Hi Lad,
Thanks for your work.
On 2020-03-10 11:06:02 +0000, Lad Prabhakar wrote:
> The rcar-csi2 driver uses the v4l2-async framework to do endpoint matching
> instead of node matching. This is needed as it needs to work with the
> adv748x driver which register it self in v4l2-async using endpoints
> instead of nodes. The reason for this is that from a single DT node it
> creates multiple subdevices, one for each endpoint.
>
> But when using subdevs which register itself in v4l2-async using nodes,
> the rcar-csi2 driver failed to find the matching endpoint because the
> match.fwnode was pointing to remote endpoint instead of remote parent
> port.
>
> This commit adds support in rcar-csi2 driver to handle both the cases
> where subdev registers in v4l2-async using endpoints/nodes, by using
> match_type as V4L2_ASYNC_MATCH_CUSTOM and implementing the match()
> callback to compare the fwnode of either remote/parent.
This is a novel approach to the solution, and I won't object to it out
right. But I think the proper solution is to move this logic into
v4l2-async instead of adding a custom match handler in rcar-csi2.
Think of the reveres use-case, a different CSI-2 receiver who wish to
use the ADV748x would still have this node vs. endpoint issue.
>
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
> ---
> drivers/media/platform/rcar-vin/rcar-csi2.c | 41 ++++++++++++++++++++++++++---
> 1 file changed, 38 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/media/platform/rcar-vin/rcar-csi2.c b/drivers/media/platform/rcar-vin/rcar-csi2.c
> index faa9fb2..39e1639 100644
> --- a/drivers/media/platform/rcar-vin/rcar-csi2.c
> +++ b/drivers/media/platform/rcar-vin/rcar-csi2.c
> @@ -808,6 +808,41 @@ static int rcsi2_parse_v4l2(struct rcar_csi2 *priv,
> return 0;
> }
>
> +static bool rcsi2_asd_match(struct device *dev,
> + struct v4l2_async_subdev *async_sd)
> +{
> + struct rcar_csi2 *priv = (struct rcar_csi2 *)
> + async_sd->match.custom.priv;
> + struct fwnode_handle *endpoint;
> + struct fwnode_handle *remote;
> + struct fwnode_handle *parent;
> + struct device_node *np;
> + bool matched = false;
> +
> + np = of_graph_get_endpoint_by_regs(priv->dev->of_node, 0, 0);
> + if (!np) {
> + dev_err(priv->dev, "Not connected to subdevice\n");
> + return -EINVAL;
You can't return -EINVAL here as it will be interpreted as a match by
the caller ;-). You should not even register a device with v4l2-async
if it's not connected to an endpoint.
> + }
> +
> + endpoint = of_fwnode_handle(np);
> + remote = fwnode_graph_get_remote_endpoint(endpoint);
> + parent = fwnode_graph_get_remote_port_parent(endpoint);
> + if (parent) {
This is wrong, we will always have a parent and will always take this
code path. Hence reducing this to the equivalent of node only matching.
I applied this patch and tried on M3-N with a ADv748x and the wrong
endpoints of the ADV7482 is routed to the two CSI-2 receivers, breaking
it.
I added some debug printouts to explain whats going on:
* First call
dev: rcar-csi2 fea80000.csi2
endpoint: /soc/csi2@feaa0000/ports/port@0/endpoint
remote: /soc/i2c@e66d8000/video-receiver@70/port@a/endpoint
parent: /soc/i2c@e66d8000/video-receiver@70
dev->fwnode: /soc/csi2@fea80000
dev->of_node: /soc/csi2@fea80000
match: false
* Second call
dev: adv748x 4-0070
endpoint: /soc/csi2@feaa0000/ports/port@0/endpoint
remote: /soc/i2c@e66d8000/video-receiver@70/port@a/endpoint
parent: /soc/i2c@e66d8000/video-receiver@70
dev->fwnode: /soc/i2c@e66d8000/video-receiver@70
dev->of_node: /soc/i2c@e66d8000/video-receiver@70
match: true
* Third call
dev: adv748x 4-0070
endpoint: /soc/csi2@fea80000/ports/port@0/endpoint
remote: /soc/i2c@e66d8000/video-receiver@70/port@b/endpoint
parent: /soc/i2c@e66d8000/video-receiver@70
dev->fwnode: /soc/i2c@e66d8000/video-receiver@70
dev->of_node: /soc/i2c@e66d8000/video-receiver@70
match: true
Now we have a media graph that is completely probed and video devices
register in the system but you are not able to stream video as the wrong
CSI-2 transmitter is described in the graph to be connected to the wrong
receiver.
This only strengthens my view that this should not be fixed with a
custom matcher in rcar-csi2 but directly in v4l-async. Please see if you
can't address the issue in the framework to allow node and endpoint
matching to co-exists.
> + if (parent == dev->fwnode ||
> + parent == &dev->of_node->fwnode)
> + matched = true;
> + } else if (remote && !matched) {
No need to check !matched here ;-)
> + if (remote == dev->fwnode ||
> + remote == &dev->of_node->fwnode)
> + matched = true;
> + }
> +
> + of_node_put(np);
> +
> + return matched;
> +}
> +
> static int rcsi2_parse_dt(struct rcar_csi2 *priv)
> {
> struct device_node *ep;
> @@ -833,9 +868,9 @@ static int rcsi2_parse_dt(struct rcar_csi2 *priv)
> return ret;
> }
>
> - priv->asd.match.fwnode =
> - fwnode_graph_get_remote_endpoint(of_fwnode_handle(ep));
> - priv->asd.match_type = V4L2_ASYNC_MATCH_FWNODE;
> + priv->asd.match.custom.match = &rcsi2_asd_match;
> + priv->asd.match.custom.priv = priv;
> + priv->asd.match_type = V4L2_ASYNC_MATCH_CUSTOM;
>
> of_node_put(ep);
>
> --
> 2.7.4
>
--
Regards,
Niklas Söderlund
