Re: [PATCH v5 00/39] i.MX Media Driver

[Philipp Zabel <p.zabel@pengutronix.de>]

On Sun, 2017-03-19 at 12:14 +0000, Russell King - ARM Linux wrote:
> On Sat, Mar 18, 2017 at 12:58:27PM -0700, Steve Longerbeam wrote:
> > On 03/18/2017 12:22 PM, Russell King - ARM Linux wrote:
> > >0:00:01.955927879 20954  0x15ffe90 INFO                    v4l2 gstv4l2object.c:3811:gst_v4l2_object_get_caps:<v4l2src0> probed caps: video/x-bayer, format=(string)rggb, framerate=(fraction)30000/1001, width=(int)816, height=(int)616, pixel-aspect-ratio=(fraction)1/1; video/x-raw, format=(string)I420, framerate=(fraction)30000/1001, width=(int)816, height=(int)616, interlace-mode=(string)progressive, pixel-aspect-ratio=(fraction)1/1; video/x-raw, format=(string)YV12, framerate=(fraction)30000/1001, width=(int)816, height=(int)616, interlace-mode=(string)progressive, pixel-aspect-ratio=(fraction)1/1; video/x-raw, format=(string)BGR, framerate=(fraction)30000/1001, width=(int)816, height=(int)616, interlace-mode=(string)progressive, pixel-aspect-ratio=(fraction)1/1; video/x-raw, format=
 (string)RGB, framerate=(fraction)30000/1001, width=(int)816, height=(int)616, interlace-mode=(string)progressive, pixel-aspect-ratio=(fraction)1/1
> > >
> > >    despite the media pipeline actually being configured for 60fps.
> > >
> > >    Forcing it by adjusting the pipeline only results in gstreamer
> > >    failing, because it believes that v4l2 is unable to operate at
> > >    60fps.
> > >
> > >    Also note the complaints from v4l2src about the non-compliance...
> > 
> > Thanks, I've fixed most of v4l2-compliance issues, but this is not
> > done yet. Is that something you can help with?
> 
> I've looked at this, and IMHO it's yet another media control API mess.
> 
> - media-ctl itself allows setting the format on subdev pads via
>   struct v4l2_subdev_format.
> 
> - struct v4l2_subdev_format contains a struct v4l2_mbus_framefmt.
> 
> - struct v4l2_mbus_framefmt contains:
>   * @width:      frame width
>   * @height:     frame 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)
>   * @quantization: quantization of the data (from enum v4l2_quantization)
>   * @xfer_func:  transfer function of the data (from enum v4l2_xfer_func)
> 
> - media-ctl sets width, height, code and field, but nothing else.
> 
> We're already agreed that the fields that media-ctl are part of the
> format negotiation between the ultimate source, flowing down to the
> capture device.  However, there's no support in media-ctl to deal
> with these other fields - so media-ctl in itself is only half-
> implemented.

To set and read colorimetry information:
https://patchwork.linuxtv.org/patch/39350/

regards
Philipp