linux-kernel - Re: [PATCH v1] media: i2c: ov5640: Implement get_mbus

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Message-ID: <b851143625401cac631b099e1b496bc726e19e4d.camel@toradex.com>
Date:   Sat, 28 Jan 2023 11:36:49 +0000
From:   Marcel Ziswiler <marcel.ziswiler@...adex.com>
To:     "jacopo.mondi@...asonboard.com" <jacopo.mondi@...asonboard.com>,
        "laurent.pinchart@...asonboard.com" 
        <laurent.pinchart@...asonboard.com>
CC:     "linux-media@...r.kernel.org" <linux-media@...r.kernel.org>,
        "slongerbeam@...il.com" <slongerbeam@...il.com>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        Aishwarya Kothari <aishwarya.kothari@...adex.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Francesco Dolcini <francesco.dolcini@...adex.com>,
        "p.zabel@...gutronix.de" <p.zabel@...gutronix.de>,
        "mchehab@...nel.org" <mchehab@...nel.org>,
        "sakari.ailus@...ux.intel.com" <sakari.ailus@...ux.intel.com>
Subject: Re: [PATCH v1] media: i2c: ov5640: Implement get_mbus_config

Hi Laurent

On Fri, 2023-01-27 at 20:34 +0200, Laurent Pinchart wrote:
> On Fri, Jan 27, 2023 at 06:50:03PM +0100, Jacopo Mondi wrote:
> > On Fri, Jan 27, 2023 at 04:12:44PM +0100, Marcel Ziswiler wrote:
> > > From: Aishwarya Kothari <aishwarya.kothari@...adex.com>
> > > 
> > > Implement the introduced get_mbus_config operation to report the
> > > number of used data lanes on the MIPI CSI-2 interface.
> > > 
> > 
> > OV5640 can operate in parallel mode too.
> > 
> > You can check how it currently configured with ov5640_is_csi2() and
> > populate struct v4l2_mbus_config accordingly.
> 
> I'm also wondering which CSI-2 receiver needs .get_mbus_config() for the
> ov5640. The number of lanes is usually specified in DT, on both sides of
> the link. It's only when selecting a number of lanes dynamically at
> runtime that .get_mbus_config() is needed.

Remember, this is on Apalis iMX6 where we do and always did specify the lanes on both sides of the link ([1],
[2]) or are we missing anything else in that respect?

Fact is, that with this patch (and the two from Hans [3], [4]) all starts working again. So it really seems
required.

[1]
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm/boot/dts/imx6qdl-apalis.dtsi#n710
[2]
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm/boot/dts/imx6qdl-apalis.dtsi#n755
[3] https://lore.kernel.org/all/69624c54-7cbd-7362-c468-f8ffea9614be@xs4all.nl/
[4] https://lore.kernel.org/all/c12cfcc5-1d46-7b5f-4a27-f4cd52a1b885@xs4all.nl/

Cheers

Marcel

> > > Signed-off-by: Aishwarya Kothari <aishwarya.kothari@...adex.com>
> > > Signed-off-by: Marcel Ziswiler <marcel.ziswiler@...adex.com>
> > > 
> > > ---
> > > 
> > >  drivers/media/i2c/ov5640.c | 14 ++++++++++++++
> > >  1 file changed, 14 insertions(+)
> > > 
> > > diff --git a/drivers/media/i2c/ov5640.c b/drivers/media/i2c/ov5640.c
> > > index e0f908af581b..42d43f0d1e1c 100644
> > > --- a/drivers/media/i2c/ov5640.c
> > > +++ b/drivers/media/i2c/ov5640.c
> > > @@ -3733,6 +3733,19 @@ static int ov5640_init_cfg(struct v4l2_subdev *sd,
> > >         return 0;
> > >  }
> > > 
> > > +static int ov5640_get_mbus_config(struct v4l2_subdev *sd,
> > > +                                  unsigned int pad,
> > > +                                  struct v4l2_mbus_config *cfg)
> > > +{
> > > +       struct ov5640_dev *sensor = to_ov5640_dev(sd);
> > > +
> > > +       cfg->type = V4L2_MBUS_CSI2_DPHY;
> > > +       cfg->bus.mipi_csi2.num_data_lanes = sensor->ep.bus.mipi_csi2.num_data_lanes;
> > > +       cfg->bus.mipi_csi2.flags = 0;
> > > +
> > > +       return 0;
> > > +}
> > > +
> > >  static const struct v4l2_subdev_core_ops ov5640_core_ops = {
> > >         .log_status = v4l2_ctrl_subdev_log_status,
> > >         .subscribe_event = v4l2_ctrl_subdev_subscribe_event,
> > > @@ -3753,6 +3766,7 @@ static const struct v4l2_subdev_pad_ops ov5640_pad_ops = {
> > >         .get_selection = ov5640_get_selection,
> > >         .enum_frame_size = ov5640_enum_frame_size,
> > >         .enum_frame_interval = ov5640_enum_frame_interval,
> > > +       .get_mbus_config = ov5640_get_mbus_config,
> > >  };
> > > 
> > >  static const struct v4l2_subdev_ops ov5640_subdev_ops = {