[PATCH 10/16] media: sun6i-csi: Add support for MC-centric format enumeration

[arash golgol]

Hi Paul,

On Mon, May 18, 2026 at 2:00 PM Paul Kocialkowski <paulk at sys-base.io> wrote:
>
> Use the dedicated helper to check possible pixelformats against the
> provided mbus code in order to support MC-centric format enumeration.
>
> Note that multiple pixelformats may be returned for a given mbus code.
>
> Signed-off-by: Paul Kocialkowski <paulk at sys-base.io>
> ---
>  .../sunxi/sun6i-csi/sun6i_csi_capture.c       | 38 +++++++++++++++++--
>  1 file changed, 34 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi_capture.c b/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi_capture.c
> index a836fa7f081a..409c28621093 100644
> --- a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi_capture.c
> +++ b/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi_capture.c
> @@ -773,14 +773,43 @@ static int sun6i_csi_capture_querycap(struct file *file, void *priv,
>  static int sun6i_csi_capture_enum_fmt(struct file *file, void *priv,
>                                       struct v4l2_fmtdesc *fmtdesc)
>  {
> +       const struct sun6i_csi_capture_format *capture_format;
> +       const struct sun6i_csi_bridge_format *bridge_format;
> +       u32 mbus_code = fmtdesc->mbus_code;
>         u32 index = fmtdesc->index;
> +       unsigned int index_valid = 0;
> +       unsigned int i;
> +
> +       /* Video-node-centric enumeration. */
> +       if (!mbus_code) {
> +               if (index >= ARRAY_SIZE(sun6i_csi_capture_formats))
> +                       return -EINVAL;
> +
> +               fmtdesc->pixelformat =
> +                       sun6i_csi_capture_formats[index].pixelformat;
> +               return 0;
> +       }
>
> -       if (index >= ARRAY_SIZE(sun6i_csi_capture_formats))
> +       bridge_format = sun6i_csi_bridge_format_find(mbus_code);
> +       if (!bridge_format)
>                 return -EINVAL;
>
> -       fmtdesc->pixelformat = sun6i_csi_capture_formats[index].pixelformat;
> +       for (i = 0; i < ARRAY_SIZE(sun6i_csi_capture_formats); i++) {
> +               capture_format = &sun6i_csi_capture_formats[i];
>
> -       return 0;
> +               if (!sun6i_csi_capture_format_check(capture_format,
> +                                                   bridge_format))
> +                       continue;
> +
> +               if (index_valid == index) {
> +                       fmtdesc->pixelformat = capture_format->pixelformat;
> +                       return 0;
> +               }
> +
> +               index_valid++;
> +       }
> +
> +       return -EINVAL;
>  }
>
>  static int sun6i_csi_capture_enum_framesize(struct file *file, void *fh,
> @@ -1076,7 +1105,8 @@ int sun6i_csi_capture_setup(struct sun6i_csi_device *csi_dev)
>
>         strscpy(video_dev->name, SUN6I_CSI_CAPTURE_NAME,
>                 sizeof(video_dev->name));
> -       video_dev->device_caps = V4L2_CAP_VIDEO_CAPTURE | V4L2_CAP_STREAMING;
> +       video_dev->device_caps = V4L2_CAP_VIDEO_CAPTURE | V4L2_CAP_STREAMING |
> +                                V4L2_CAP_IO_MC;
>         video_dev->vfl_dir = VFL_DIR_RX;
>         video_dev->release = video_device_release_empty;
>         video_dev->fops = &sun6i_csi_capture_fops;
> --
> 2.54.0
>

Tested on a LicheePi Zero Dock (V3s) with the following pipeline:

ov7670 -> sun6i-csi-bridge -> sun6i-csi-capture

I verified that mbus-code-based format enumeration works correctly
from userspace and that the reported capture formats change according
to the selected media bus format.

I could also successfully start streaming with several of the
enumerated capture formats (e.g. YUYV and BA81)

However, I could not fully validate actual format conversion behavior
(e.g. MEDIA_BUS_FMT_YUYV8_2X8 to NV12) because my OV7670 setup
currently has non-functional test patterns except for 'shifting-1'
mode.

Tested-by: Arash Golgol <arash.golgol at gmail.com>

PS:

While testing this patch I also noticed that
VIDIOC_SUBDEV_ENUM_MBUS_CODE reports duplicate entries for:
 - MEDIA_BUS_FMT_UYVY8_2X8
 - MEDIA_BUS_FMT_UYVY8_1X16
on sun6i-csi-bridge.

This appears to come from duplicate format entries being exposed by
the bridge driver.

-- 
Regards,
Arash Golgol