Hi Ezequiel,
thank you for picking this up.
On Sun, 2021-01-03 at 12:41 -0300, Ezequiel Garcia wrote:
> Currently, the CSI2 subdevice is using the data-lanes from the
> neareast endpoint to config the CSI2 lanes.
>
> While this may work, the proper way to configure the hardware is
> to obtain the remote subdevice in v4l2_async_notifier_operations.bound(),
> and then call get_mbus_config using the remote subdevice to get
> the active lanes.
>
> Signed-off-by: Ezequiel Garcia <ezequiel@xxxxxxxxxxxxx>
> Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
Same comment as Laurent, csi2_get_active_lanes() looks to be the same as
rcsi2_get_active_lanes() in rcar-csi2, so this could benefit from a
common helper (later).
Reviewed-by: Philipp Zabel <p.zabel@xxxxxxxxxxxxxx>
> ---
> drivers/staging/media/imx/TODO | 12 ---
> drivers/staging/media/imx/imx6-mipi-csi2.c | 99 +++++++++++++++++++---
> 2 files changed, 87 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/staging/media/imx/TODO b/drivers/staging/media/imx/TODO
> index 9cfc1c1e78dc..c575f419204a 100644
> --- a/drivers/staging/media/imx/TODO
> +++ b/drivers/staging/media/imx/TODO
> @@ -2,18 +2,6 @@
> - The Frame Interval Monitor could be exported to v4l2-core for
> general use.
>
> -- The CSI subdevice parses its nearest upstream neighbor's device-tree
> - bus config in order to setup the CSI. Laurent Pinchart argues that
> - instead the CSI subdev should call its neighbor's g_mbus_config op
> - (which should be propagated if necessary) to get this info. However
> - Hans Verkuil is planning to remove the g_mbus_config op. For now this
> - driver uses the parsed DT bus config method until this issue is
> - resolved.
> -
> - 2020-06: g_mbus has been removed in favour of the get_mbus_config pad
> - operation which should be used to avoid parsing the remote endpoint
> - configuration.
> -
> - This media driver supports inheriting V4L2 controls to the
> video capture devices, from the subdevices in the capture device's
> pipeline. The controls for each capture device are updated in the
> diff --git a/drivers/staging/media/imx/imx6-mipi-csi2.c b/drivers/staging/media/imx/imx6-mipi-csi2.c
> index 94d87d27d389..8cfd6358c306 100644
> --- a/drivers/staging/media/imx/imx6-mipi-csi2.c
> +++ b/drivers/staging/media/imx/imx6-mipi-csi2.c
[...]
> @@ -300,8 +300,56 @@ static void csi2ipu_gasket_init(struct csi2_dev *csi2)
> writel(reg, csi2->base + CSI2IPU_GASKET);
> }
>
> +static int csi2_get_active_lanes(struct csi2_dev *csi2, unsigned int *lanes)
> +{
> + struct v4l2_mbus_config mbus_config = { 0 };
> + unsigned int num_lanes = UINT_MAX;
> + int ret;
> +
> + *lanes = csi2->data_lanes;
> +
> + ret = v4l2_subdev_call(csi2->remote, pad, get_mbus_config,
> + csi2->remote_pad, &mbus_config);
> + if (ret == -ENOIOCTLCMD) {
> + dev_dbg(csi2->dev, "No remote mbus configuration available\n");
> + return 0;
> + }
> +
> + if (ret) {
> + dev_err(csi2->dev, "Failed to get remote mbus configuration\n");
> + return ret;
> + }
> +
> + if (mbus_config.type != V4L2_MBUS_CSI2_DPHY) {
> + dev_err(csi2->dev, "Unsupported media bus type %u\n",
> + mbus_config.type);
> + return -EINVAL;
> + }
> +
> + if (mbus_config.flags & V4L2_MBUS_CSI2_1_LANE)
> + num_lanes = 1;
> + else if (mbus_config.flags & V4L2_MBUS_CSI2_2_LANE)
> + num_lanes = 2;
> + else if (mbus_config.flags & V4L2_MBUS_CSI2_3_LANE)
> + num_lanes = 3;
> + else if (mbus_config.flags & V4L2_MBUS_CSI2_4_LANE)
> + num_lanes = 4;
I'd turn this into a
switch (mbus_config.flags & V4L2_MBUS_CSI2_LANES) { }
to catch erroneous values of 0 or multiple bits set, as for those the
following error message doesn't make much sense:
> + if (num_lanes > csi2->data_lanes) {
> + dev_err(csi2->dev,
> + "Unsupported mbus config: too many data lanes %u\n",
> + num_lanes);
> + return -EINVAL;
> + }
> +
> + *lanes = num_lanes;
> +
> + return 0;
> +}
Still, this patch looks good to me.
regards
Philipp
