[PATCH v2 0/3] media: uvcvideo: live pan/tilt/zoom readback on the OBSBOT Tiny 2

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

The OBSBOT Tiny 2's GET_INFO strips the AUTOUPDATE bit from its pan,
tilt and zoom controls, so uvcvideo caches them and userspace can never
observe the actuator's live state. This series reports AUTO_UPDATE
controls as volatile to userspace, generalises the existing XU flags
fixup table to all controls, and adds entries for the three affected
controls on this camera.

Changes in v2 (following Ricardo's review of v1 [1]):

- Patch 1: unchanged; picked up Ricardo's Reviewed-by.
- Patch 2: uvc_ctrl_fixup_flags() now returns bool and runs at the
  start of uvc_ctrl_get_flags(), before the allocation, skipping the
  GET_INFO query entirely for controls the table covers (Ricardo).
- Patch 3: as asked, I checked whether the camera's other
  AUTO_UPDATE-flagged controls suffer the same bug. Two more do:
  CT_PANTILT_RELATIVE and CT_ZOOM_ABSOLUTE, both verified on hardware
  to change autonomously and report live values on GET_CUR; entries
  added for both. Exposure, white balance and focus turned out to be
  write-only on this firmware (their autos work, but GET_CUR echoes the
  last SET_CUR), so they gain nothing from AUTO_UPDATE and were left
  alone; details in the commit message. The commit message also no
  longer claims the capability byte is the same for every control --
  probing every control showed it is computed per control, just wrong
  for the PTZ ones. Dropped Ricardo's Reviewed-by since the patch
  changed materially.

The full lsusb -v output was posted in reply to v1's patch 3, in the
thread at [1].

[1] https://lore.kernel.org/linux-media/20260828152557.653475-1-jordan.mymail@gmail.com/

Michael Jordan (3):
  media: uvcvideo: report AUTO_UPDATE controls as volatile
  media: uvcvideo: generalise the XU flags fixup to all controls
  media: uvcvideo: fix up missing AUTO_UPDATE on the OBSBOT Tiny 2

 drivers/media/usb/uvc/uvc_ctrl.c | 122 ++++++++++++++++++++-----------
 1 file changed, 81 insertions(+), 41 deletions(-)

-- 
2.43.0