Re: [linux-sunxi] [PATCH v4 09/15] media: sunxi: Add support for the A31 MIPI CSI-2 controller

Paul Kocialkowski
2021-01-14T09:31:09Z

[-- Attachment #1: Type: text/plain, Size: 4487 bytes --]

Hey Ezequiel,

On Mon 11 Jan 21, 15:21, Ezequiel Garcia wrote:
> Salut Paul,
>
> Just a minor comment about the v4l2 async API.
>
> On Thu, 31 Dec 2020 at 11:30, Paul Kocialkowski
> <paul.kocialkowski@bootlin.com> wrote:
> >
> > The A31 MIPI CSI-2 controller is a dedicated MIPI CSI-2 bridge
> > found on Allwinner SoCs such as the A31 and V3/V3s.
> >
> > It is a standalone block, connected to the CSI controller on one side
> > and to the MIPI D-PHY block on the other. It has a dedicated address
> > space, interrupt line and clock.
> >
> > It is represented as a V4L2 subdev to the CSI controller and takes a
> > MIPI CSI-2 sensor as its own subdev, all using the fwnode graph and
> > media controller API.
> >
> > Only 8-bit and 10-bit Bayer formats are currently supported.
> > While up to 4 internal channels to the CSI controller exist, only one
> > is currently supported by this implementation.
> >
> > Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
> > ---
> > drivers/media/platform/sunxi/Kconfig | 1 +
> > drivers/media/platform/sunxi/Makefile | 1 +
> > .../platform/sunxi/sun6i-mipi-csi2/Kconfig | 12 +
> > .../platform/sunxi/sun6i-mipi-csi2/Makefile | 4 +
> > .../sunxi/sun6i-mipi-csi2/sun6i_mipi_csi2.c | 590 ++++++++++++++++++
> > .../sunxi/sun6i-mipi-csi2/sun6i_mipi_csi2.h | 117 ++++
> > 6 files changed, 725 insertions(+)
> > create mode 100644 drivers/media/platform/sunxi/sun6i-mipi-csi2/Kconfig
> > create mode 100644 drivers/media/platform/sunxi/sun6i-mipi-csi2/Makefile
> > create mode 100644 drivers/media/platform/sunxi/sun6i-mipi-csi2/sun6i_mipi_csi2.c
> > create mode 100644 drivers/media/platform/sunxi/sun6i-mipi-csi2/sun6i_mipi_csi2.h
> >
> [..]
> > +static int sun6i_mipi_csi2_v4l2_setup(struct sun6i_mipi_csi2_dev *cdev)
> > +{
> > + struct sun6i_mipi_csi2_video *video = &cdev->video;
> > + struct v4l2_subdev *subdev = &video->subdev;
> > + struct v4l2_async_notifier *notifier = &video->notifier;
> > + struct fwnode_handle *handle;
> > + struct v4l2_fwnode_endpoint *endpoint;
> > + struct v4l2_async_subdev *subdev_async;
> > + int ret;
> > +
> > + /* Subdev */
> > +
> > + v4l2_subdev_init(subdev, &sun6i_mipi_csi2_subdev_ops);
> > + subdev->dev = cdev->dev;
> > + subdev->flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
> > + strscpy(subdev->name, MODULE_NAME, sizeof(subdev->name));
> > + v4l2_set_subdevdata(subdev, cdev);
> > +
> > + /* Entity */
> > +
> > + subdev->entity.function = MEDIA_ENT_F_VID_IF_BRIDGE;
> > + subdev->entity.ops = &sun6i_mipi_csi2_entity_ops;
> > +
> > + /* Pads */
> > +
> > + video->pads[0].flags = MEDIA_PAD_FL_SINK;
> > + video->pads[1].flags = MEDIA_PAD_FL_SOURCE;
> > +
> > + ret = media_entity_pads_init(&subdev->entity, 2, video->pads);
> > + if (ret)
> > + return ret;
> > +
> > + /* Endpoint */
> > +
> > + handle = fwnode_graph_get_endpoint_by_id(dev_fwnode(cdev->dev), 0, 0,
> > + FWNODE_GRAPH_ENDPOINT_NEXT);
> > + if (!handle) {
> > + ret = -ENODEV;
> > + goto error_media_entity;
> > + }
> > +
> > + endpoint = &video->endpoint;
> > + endpoint->bus_type = V4L2_MBUS_CSI2_DPHY;
> > +
> > + ret = v4l2_fwnode_endpoint_parse(handle, endpoint);
> > + fwnode_handle_put(handle);
>
> I think the _put should be...
>
> > + if (ret)
> > + goto error_media_entity;
> > +
> > + /* Notifier */
> > +
> > + v4l2_async_notifier_init(notifier);
> > +
> > + subdev_async = &video->subdev_async;
> > + ret = v4l2_async_notifier_add_fwnode_remote_subdev(notifier, handle,
> > + subdev_async);
>
> ... here. See for instance drivers/media/platform/rcar-vin/rcar-csi2.c.
>
> (Unless I've missed something, of course).

I think you're right, the reference is obtained at
fwnode_graph_get_endpoint_by_id and should be held when passing handle to
v4l2_async_notifier_add_fwnode_remote_subdev since it will be used to get
a reference to the remote port.

Good catch and thanks for the review!

Paul

--
Paul Kocialkowski, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]