On Mon, 2017-03-20 at 14:17 +0000, Russell King - ARM Linux wrote:

On Mon, Mar 20, 2017 at 03:00:51PM +0100, Philipp Zabel wrote:

quoted

On Mon, 2017-03-20 at 12:08 +0000, Russell King - ARM Linux wrote:

quoted

The same document says:

  Scaling support is optional. When supported by a subdev, the crop
  rectangle on the subdev's sink pad is scaled to the size configured
  using the
  :ref:`VIDIOC_SUBDEV_S_SELECTION <VIDIOC_SUBDEV_G_SELECTION>` IOCTL
  using ``V4L2_SEL_TGT_COMPOSE`` selection target on the same pad. If the
  subdev supports scaling but not composing, the top and left values are
  not used and must always be set to zero.

Right, this sentence does imply that when scaling is supported, there
must be a sink compose rectangle, even when composing is not.

I have previously set up scaling like this:

media-ctl --set-v4l2 "'ipu1_csi0_mux':2[fmt:UYVY2X8/1920x1080 at 1/60]"
media-ctl --set-v4l2 "'ipu1_csi0':2[fmt:AYUV32/960x540 at 1/30]"

Does this mean, it should work like this instead?

media-ctl --set-v4l2 "'ipu1_csi0_mux':2[fmt:UYVY2X8/1920x1080 at 1/60]"
media-ctl --set-v4l2 "'ipu1_csi0':0[fmt:UYVY2X8/1920x1080 at 1/60,compose:(0,0)/960x540]"
media-ctl --set-v4l2 "'ipu1_csi0':2[fmt:AYUV32/960x540 at 1/30]"

I suppose setting the source pad format should not be allowed to modify
the sink compose rectangle.

That is what I believe having read these documents several times, but
we need v4l2 people to confirm.

Note that setting the format on 'ipu1_csi0':0 should already be done by
the previous media-ctl command, so it should be possible to simplify
that to:

media-ctl --set-v4l2 "'ipu1_csi0_mux':2[fmt:UYVY2X8/1920x1080 at 1/60]"
media-ctl --set-v4l2 "'ipu1_csi0':0[compose:(0,0)/960x540]"
media-ctl --set-v4l2 "'ipu1_csi0':2[fmt:AYUV32/960x540 at 1/30]"

Thanks, that works, too.

I have tripped over a bug in media-ctl when specifying both a crop and
compose rectangle - the --help output suggests that "," should be used
to separate them.  media-ctl rejects that, telling me the character at
the "," should be "]".  Replacing the "," with " " allows media-ctl to
accept it and set both rectangles, so it sounds like a parser bug - I've
not looked into this any further yet.

I can confirm this. I don't see any place in
v4l2_subdev_parse_pad_format that handles the "," separator. There's
just whitespace skipping between the v4l2-properties.

regards
Philipp