linux-kernel - Re: [PATCH] media: adv7180: Fix media bus format

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Date:   Thu, 27 Jan 2022 13:45:25 +0000
From:   Dave Stevenson <dave.stevenson@...pberrypi.com>
To:     Jean-Michel Hautbois <jeanmichel.hautbois@...asonboard.com>
Cc:     Linux Media Mailing List <linux-media@...r.kernel.org>,
        lars@...afoo.de, Mauro Carvalho Chehab <mchehab@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>
Subject: Re: [PATCH] media: adv7180: Fix media bus format

Hi Jean-Michel

On Thu, 27 Jan 2022 at 10:09, Jean-Michel Hautbois
<jeanmichel.hautbois@...asonboard.com> wrote:
>
> MEDIA_BUS_FMT_UYVY8_2X8 isn't correct for CSI-2. Use
> MEDIA_BUS_FMT_UYVY8_1X16 instead.

2X8 isn't correct for CSI-2, but it is correct for the parallel
configuration that is also supported by this driver.

Referencing the adv7180 datasheet[1] page 76, OF_SEL (bits [5:2] of
register 0x03) are 0010b for 16bit, or 0011b for 8 bit.
[2] in the driver sets these bits to 0011b, so it is in 2x8 mode.

You may be able to get away with a simple check of
if (state->chip_info->flags & ADV7180_FLAG_MIPI_CSI2)
  fmt->code = MEDIA_BUS_FMT_UYVY8_1X16;
else
  fmt->code = MEDIA_BUS_FMT_UYVY8_2X8;
but I haven't examined all the potential options.

  Dave

[1] https://www.analog.com/media/en/technical-documentation/data-sheets/ADV7180.pdf
[2] https://github.com/torvalds/linux/blob/master/drivers/media/i2c/adv7180.c#L1006

> Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@...asonboard.com>
> ---
>  drivers/media/i2c/adv7180.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/media/i2c/adv7180.c b/drivers/media/i2c/adv7180.c
> index d9a99fcfacb1..cbededfb6b3f 100644
> --- a/drivers/media/i2c/adv7180.c
> +++ b/drivers/media/i2c/adv7180.c
> @@ -655,7 +655,7 @@ static int adv7180_enum_mbus_code(struct v4l2_subdev *sd,
>         if (code->index != 0)
>                 return -EINVAL;
>
> -       code->code = MEDIA_BUS_FMT_UYVY8_2X8;
> +       code->code = MEDIA_BUS_FMT_UYVY8_1X16;
>
>         return 0;
>  }
> @@ -665,7 +665,7 @@ static int adv7180_mbus_fmt(struct v4l2_subdev *sd,
>  {
>         struct adv7180_state *state = to_state(sd);
>
> -       fmt->code = MEDIA_BUS_FMT_UYVY8_2X8;
> +       fmt->code = MEDIA_BUS_FMT_UYVY8_1X16;
>         fmt->colorspace = V4L2_COLORSPACE_SMPTE170M;
>         fmt->width = 720;
>         fmt->height = state->curr_norm & V4L2_STD_525_60 ? 480 : 576;
> --
> 2.32.0
>