On Mon, Aug 14, 2023 at 10:23:59AM +0000, Sakari Ailus wrote:
> On Thu, Aug 10, 2023 at 05:19:02PM +0200, Jacopo Mondi wrote:
> > On Tue, Aug 08, 2023 at 10:55:33AM +0300, Sakari Ailus wrote:
> > > Now that metadata mbus formats have been added, it is necessary to define
> > > which fields in struct v4l2_mbus_format are applicable to them (not many).
> > >
> > > Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
> > > ---
> > > include/uapi/linux/v4l2-mediabus.h | 18 ++++++++++++------
> > > 1 file changed, 12 insertions(+), 6 deletions(-)
> > >
> > > diff --git a/include/uapi/linux/v4l2-mediabus.h b/include/uapi/linux/v4l2-mediabus.h
> > > index 6b07b73473b5..3cadb3b58b85 100644
> > > --- a/include/uapi/linux/v4l2-mediabus.h
> > > +++ b/include/uapi/linux/v4l2-mediabus.h
> > > @@ -19,12 +19,18 @@
> > > * @width: image width
> > > * @height: image height
> > > * @code: data format code (from enum v4l2_mbus_pixelcode)
> > > - * @field: used interlacing type (from enum v4l2_field)
> > > - * @colorspace: colorspace of the data (from enum v4l2_colorspace)
> > > - * @ycbcr_enc: YCbCr encoding of the data (from enum v4l2_ycbcr_encoding)
> > > - * @hsv_enc: HSV encoding of the data (from enum v4l2_hsv_encoding)
> > > - * @quantization: quantization of the data (from enum v4l2_quantization)
> > > - * @xfer_func: transfer function of the data (from enum v4l2_xfer_func)
> > > + * @field: used interlacing type (from enum v4l2_field), not applicable
> > > + * to metadata mbus codes
> >
> > "not applicable" is a bit geeric. Should this be set to
> > V4L2_FIELD_NONE (for metadata, and progressive image formats maybe ?)
>
> I actually intended to have the same wording here than for the other fields
> but missed changing this.
>
> 0 corresponds to V4L2_FIELD_ANY.
>
> > > + * @colorspace: colorspace of the data (from enum v4l2_colorspace), zero on
> > > + * metadata mbus codes
> > > + * @ycbcr_enc: YCbCr encoding of the data (from enum v4l2_ycbcr_encoding), zero
> > > + * on metadata mbus codes
> > > + * @hsv_enc: HSV encoding of the data (from enum v4l2_hsv_encoding), zero on
> > > + * metadata mbus codes
> >
> > Can this be zero ?
> >
> > enum v4l2_hsv_encoding {
> >
> > /* Hue mapped to 0 - 179 */
> > V4L2_HSV_ENC_180 = 128,
> >
> > /* Hue mapped to 0-255 */
> > V4L2_HSV_ENC_256 = 129,
> > };
>
> Good question. Neither value is meaningful for metadata.
>
> The values appear to be such in the enum to avoid colliding with ycbcr
> encoding values (another field above).
>
> Generally, what doesn't matter will be zero. These fields have been added
> at some point and a lot of drivers do not set them, even for pixel data.
>
> I wonder what Hans and Laurent think.
ycbcr_enc and hsv_enc are stored in an unnamed union.
> > > + * @quantization: quantization of the data (from enum v4l2_quantization), zero
> > > + * on metadata mbus codes
> > > + * @xfer_func: transfer function of the data (from enum v4l2_xfer_func), zero
> > > + * on metadata mbus codes
> > > * @flags: flags (V4L2_MBUS_FRAMEFMT_*)
> > > * @reserved: reserved bytes that can be later used
> > > */
--
Regards,
Laurent Pinchart
