Hi Philipp,
On Mon, 2021-01-04 at 14:41 +0100, Philipp Zabel wrote:
> Hi Ezequiel,
>
> thank you for picking this up.
>
No problem.
> 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>
>
Thanks for the review.
> > ---
> > 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:
>
Makes sense. We can do that later, once we move the function to the core.
> > + 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.
>
Thanks,
Ezequiel
