Re: [PATCH v2 3/3] media: uvcvideo: fix up missing AUTO_UPDATE on the OBSBOT Tiny 2

[Michael Jordan <jordan.mymail@gmail.com>]

Hi Ricardo,

On Wed, 2 Sep 2026 08:34:34 +0200, Ricardo Ribalda <ribalda@chromium.org> wrote:
> Reviewed-by: Ricardo Ribalda <ribalda@chromium.org>

Thanks for the reviews on v2.

I have a question about how to handle a second device. I now have an
OBSBOT Tail 2 (3564:fefc) and it has the same defect as the Tiny 2.

Its GET_INFO bytes match the Tiny 2 control for control:

  CT_PANTILT_ABSOLUTE   0x03
  CT_PANTILT_RELATIVE   0x03
  CT_ZOOM_ABSOLUTE      0x03
  CT_ZOOM_RELATIVE      0x0f
  CT_ROLL_ABSOLUTE      0x01

Without a fixup entry, pan_absolute reads back the commanded target the
moment it is written. With entries for 3564:fefc on top of v2, all three
controls report the live value on GET_CUR, both during a commanded move
and when the camera changes them on its own:

- pan/tilt position and pan/tilt speed follow the gimbal under the
  camera's subject tracking, with the host issuing no requests;
- zoom follows a zoom change made at the camera.

I checked the other AUTO_UPDATE controls the same way as for the Tiny 2.
White balance and focus only echo the last SET_CUR. Exposure time reports
live values until the host writes a manual exposure once, and from then
on echoes that value, across a power cycle. I would leave all of those
alone, as on the Tiny 2.

So the change is three more table entries, identical to the Tiny 2 ones
apart from the product ID. v2 still applies cleanly to media/next as of
2dcdfb625c3b, so nothing else forces a respin.

Which would you prefer?

 a) a v3 with the Tail 2 entries folded into 3/3;
 b) a v3 with the Tail 2 entries as a new 4/4, leaving 1-3 as reviewed;
 c) leave v2 as it is, and send the Tail 2 entries as a follow-up patch
    once v2 is applied.

I lean towards (c), so that a reviewed series is not disturbed, but I am
happy to do whichever is easiest for you and Laurent. In any of the three
I will include the Tail 2 lsusb -v output.

Thanks,
Michael