Re: [PATCH] media: ov5640: select the MIPI lane mode from the endpoint lane count

Hi Sakari,

Thanks for the review.

> I guess there wouldn't be harm from backporting either.

Agreed, switched to a plain stable Cc.

> How about:
>
>         ret = ov5640_write_reg(sensor, OV5640_REG_IO_MIPI_CTRL00,
>                                on ? 0x5 | ep.bus.mipi_csi2.num_data_lanes << 5 :
>                                0x40);

Nicer, thanks - applied, with the lane count in a local variable to
stay within 80 columns.

> Do we need quotes?

Right, dropped.

Thanks,
Jason


Sakari Ailus <[email protected]> 於 2026年8月11日週二 下午1:54寫道：
>
> Hi Jason,
>
> Thanks for the patch.
>
> On Tue, Aug 11, 2026 at 12:40:13PM +0800, Jason Yang via B4 Relay wrote:
> > From: Jason Yang <[email protected]>
> >
> > ov5640_set_stream_mipi() always programs IO_MIPI_CTRL00 with 0x45,
> > which selects the two data lane mode: the number of data lanes
> > described in the devicetree endpoint only feeds the sensor's clock
> > tree computations, so a module wired with one data lane starts
> > streaming in two lane mode and the receiver never assembles a
> > frame.
> >
> > Select the lane mode from the endpoint instead. The one lane
> > encoding is [7:5] = 001 per the current sensor manual (version
> > 2.33). The 2.03 manual documented 000/001 for one/two lanes;
> > OmniVision corrected the table in version 2.1, which is why the
> > long-standing comment here found 001 unusable for two lanes and
> > validated 010 instead.
> >
> > The power-up path also programs a two data lane mode, but that
> > value is overwritten when streaming starts, so it is left alone.
> >
> > Tested with a single data lane module on an i.MX8MP board
> > (imx-mipi-csis receiver), where the unpatched value produces no
> > frames at all, and on an RK3588 board.
> >
> > Fixes: 19a81c1426c1 ("[media] add Omnivision OV5640 sensor driver")
> > Cc: [email protected] # no in-tree 1-lane users
>
> I guess there wouldn't be harm from backporting either.
>
> > Signed-off-by: Jason Yang <[email protected]>
> > Assisted-by: Claude:claude-opus-5
> > ---
> > The three [7:5] encodings were exercised individually on the
> > i.MX8MP board (v7.2-rc4, data-lanes = <1>) by patching the value
> > and capturing with v4l2-ctl:
> >
> >   001 (this patch): 30/30 frames, zero PHY error events in
> >       steady state (3 x 300 frames)
> >   000 (2.03 manual / NXP KB): same result
> >   010 (unpatched two lane mode): no frames; the receiver logs
> >       only start-of-transmission errors and never assembles one
> >
> > The RK3588 run used the same module and devicetree (data-lanes =
> > <1>) through a Rockchip CSI-2 receiver, streaming to natural EOS
> > with a clean kernel log.
> >
> > Happy to run additional tests on either platform if that would
> > help.
> > ---
> >  drivers/media/i2c/ov5640.c | 22 +++++++++++-----------
> >  1 file changed, 11 insertions(+), 11 deletions(-)
> >
> > diff --git a/drivers/media/i2c/ov5640.c b/drivers/media/i2c/ov5640.c
> > index 8deb5f5501fa..ef731709bdc8 100644
> > --- a/drivers/media/i2c/ov5640.c
> > +++ b/drivers/media/i2c/ov5640.c
> > @@ -1826,27 +1826,27 @@ static int ov5640_set_stream_dvp(struct ov5640_dev *sensor, bool on)
> >
> >  static int ov5640_set_stream_mipi(struct ov5640_dev *sensor, bool on)
> >  {
> > +     u8 val;
> >       int ret;
> >
> >       /*
> >        * Enable/disable the MIPI interface
> >        *
> > -      * 0x300e = on ? 0x45 : 0x40
> > -      *
> > -      * FIXME: the sensor manual (version 2.03) reports
> > -      * [7:5] = 000  : 1 data lane mode
> > -      * [7:5] = 001  : 2 data lanes mode
> > -      * But this settings do not work, while the following ones
> > -      * have been validated for 2 data lanes mode.
> > -      *
> > +      * [7:5] = 001  : 1 data lane mode
> >        * [7:5] = 010  : 2 data lanes mode
> > +      *                Encodings per version 2.33 of the sensor manual.
> >        * [4] = 0      : Power up MIPI HS Tx
> >        * [3] = 0      : Power up MIPI LS Rx
> >        * [2] = 1/0    : MIPI interface enable/disable
> >        * [1:0] = 01/00: FIXME: 'debug'
> >        */
> > -     ret = ov5640_write_reg(sensor, OV5640_REG_IO_MIPI_CTRL00,
> > -                            on ? 0x45 : 0x40);
> > +     if (on)
> > +             val = sensor->ep.bus.mipi_csi2.num_data_lanes == 1 ?
> > +                   0x25 : 0x45;
>
> How about:
>
>         ret = ov5640_write_reg(sensor, OV5640_REG_IO_MIPI_CTRL00,
>                                on ? 0x5 | ep.bus.mipi_csi2.num_data_lanes << 5 :
>                                0x40);
>
> > +     else
> > +             val = 0x40;
> > +
> > +     ret = ov5640_write_reg(sensor, OV5640_REG_IO_MIPI_CTRL00, val);
> >       if (ret)
> >               return ret;
> >
> > @@ -2535,7 +2535,7 @@ static int ov5640_set_power_mipi(struct ov5640_dev *sensor, bool on)
> >        * Power up MIPI HS Tx and LS Rx; 2 data lanes mode
> >        *
> >        * 0x300e = 0x40
> > -      * [7:5] = 010  : 2 data lanes mode (see FIXME note in
> > +      * [7:5] = 010  : 2 data lanes mode (see the note in
> >        *                "ov5640_set_stream_mipi()")
>
> Do we need quotes?
>
> >        * [4] = 0      : Power up MIPI HS Tx
> >        * [3] = 0      : Power up MIPI LS Rx
> >
>
> --
> Kind regards,
>
> Sakari Ailus