[Bug 1958563] Update Released

[Brian Murray]

The verification of the Stable Release Update for raspberrypi-userland
has completed successfully and the package is now being released to
-updates.  Subsequently, the Ubuntu Stable Release Updates Team is being
unsubscribed and will not receive messages about this bug report.  In
the event that you encounter a regression using the package from
-updates please report a new bug using ubuntu-bug and tag the bug report
regression-update so we can easily find any regressions.

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https://bugs.launchpad.net/bugs/1958563

Title:
  [SRU] Wrong permissions on vcio

Status in raspberrypi-userland package in Ubuntu:
  Fix Released
Status in raspberrypi-userland source package in Focal:
  Fix Committed
Status in raspberrypi-userland source package in Impish:
  Fix Released

Bug description:
  [Impact]

  The incorrect permissions on these devices mean the regular console
  user cannot access various videocore services. An example of a side-
  effect of this is that camera usage (via the new libcamera mechanism)
  requires root access. Likewise, usage of the GPU (under the KMS
  system) for H.264 decoding (via v4l2m2m) likewise requires root
  access.

  [Test Plan]

  * Flash the appropriate version to a fresh SD card and boot it
  * sudo apt install libraspberrypi-bin  # because it's not seeded on focal (this can be skipped on impish)
  * sudo reboot
  * ls -l /dev/vc* /dev/dma_heap/
  * Note that /dev/vcio, /dev/vcsm-cma, /dev/vchiq, /dev/dma_heap/* have incorrect permissions (specifically, their ownership is not root:video and/or their mode is not 0664)
  * sudo reboot
  * sudo apt install libraspberrypi-bin
  * sudo reboot
  * ls -l /dev/vc* /dev/dma_heap/
  * Note that /dev/vcio, /dev/vcsm-cma, /dev/vchiq, /dev/dma_heap/* now have correct permissions (root:video ownership, and mode 0664)

  [Regression Potential]

  Only the permission changes are being backported, not a fully updated
  userland. Nonetheless, existing functionality from userland should be
  re-tested, in particular the legacy camera stack, with the following
  procedure:

  * Attach a raspberry pi camera module to the board
  * Add "start_x=1" and "gpu_mem=128" to /boot/firmware/config.txt
  * sudo reboot
  * raspistill -o test.jpg
  * Confirm that test.jpg contains a valid picture

  The "tvservice" binary *may* be tested too, but is known to be
  inoperable under the arm64 architecture (see LP: #1944541). It is also
  worth noting that the test plan above only looks at the permissions as
  libcamera is not *currently* expected to operate on Focal.

  Tests should be carried out on all supported boards (Zero 2, 2B, 3B,
  3A+, 3B+, 4B) under both armhf and arm64 architectures (within the
  caveats noted above about the arm64 architecture).

  [Original Description]

  The /dev/vcio can have the wrong permissions due to a change in the
  kernel. As reported in https://github.com/raspberrypi/linux/pull/4624
  (which I missed entirely, sorry pelwell!) we'll need a change in the
  udev rules to ensure the correct permissions are set.

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