[Bug 2092139] Re: Rename media device as ipu6-downstream in Noble

[You-Sheng Yang]

Need sponsor. Also uploaded to
https://launchpad.net/~vicamo/+archive/ubuntu/sru/+packages for
inspection/testing.

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https://bugs.launchpad.net/bugs/2092139

Title:
  Rename media device as ipu6-downstream in Noble

Status in ipu6-drivers package in Ubuntu:
  Invalid
Status in ipu6-drivers source package in Noble:
  In Progress

Bug description:
  [SRU Justificaiton]

  [ Impact ]

  Latest IPU6/7 userspace framework becomes incompatible with
  ipu6-drivers using out-of-tree ipu6-isys kernel module.

  1. The userspace framework has to be compatible with all kernels, and
  therefore all ipu6 kernel driver revisions, available in Noble.

  2. There are implementation differences between the upstreamed
  ipu6-isys driver and that from out-of-tree git repository. Such
  differences are identified by a media device model name.

  3. The out-of-tree driver ipu6-isys used to identify itself as "ipu6",
  but while it being upstreamed, this formal name was taken to identify
  the in-tree ipu6-isys driver, and therefore demanding the out-of-tree
  one to be renamed as "ipu6-downstream" instead.

  4. The latest userspace framework has adopted such naming policy, so
  all the kernels that are still using out-of-tree ipu6-isys with such
  name identity must take corresponding action so that it won't be
  misidentified by the framework.

  [ Test Plan ]

  1. install kernel from -proposed pocket.

  2. install necessary (ipu6/ipu7/usbio/vision) linux-modules-
  FOO-<variant> corresponding packages for the kernel.

  3. For kernels > v6.10 it should be using the in-tree ipu6-isys, and out-of-tree one for kernel < v6.10. From `v4l2-ctl` output:
  ```
  # kernel >= v6.10
  $ v4l2-ctl -D -d 1
  Driver Info:
          Driver name: intel-ipu6-isys
          Card type  : ipu6

  # kernel > v6.10
  $ v4l2-ctl -D -d 1
  Driver Info:
          Driver name: intel-ipu6-isys
          Card type  : ipu6-downstream
  ```

  4. Use https://webcamtests.com/ to verify camera availability.

  [ Where problems could occur ]

  For old userspace framework, there is no such identity checks, so the
  new identity for the out-of-tree driver doesn't have an effect for the
  existing setups.

  [ Other Info ]

  This is already part of the drivers for kernel >= v6.10, and therefore
  it affects only ipu6-drivers/noble.

  ========== original bug report ==========

  The Intel's ARL enablement release (bug 2085845) also makes use of in-
  tree IPU6 ISYS kernel modules for kernel versions >= 6.10. This is not
  optional, and the differences between the in-tree and out-of-tree isys
  kernel modules result in the need of the compatibility handling only
  available in userspace HAL >= 20241122. The new kernel driver depends
  on the new HAL.

  To be worse, the media device model name that used to be "ipu6" is
  chosen to serve as an identity to distinguish the upstream (in-tree)
  and downstream (out-of-tree) implementation of isys. While the
  upstreamed isys driver must use "ipu6" as the model name, it means the
  downstream one has to rename media device model as "ipu6-downstream".
  Since the old ipu6-drivers always use "ipu6", and the new HAL assumes
  "ipu" means the in-tree isys but it's not, all the old ipu6-drivers
  deployments has to rename their media device model to
  "ipu6-downstream" when using the new HAL.

  Then, the last problem, Noble has both oem-6.11 and oem-6.8, which
  follows the oem-6.11 will need the new HAL, and the new HAL demands
  intel-isys module built along with oem-6.8 to be renamed as
  "ipu6-downstream".

  Proposed fix: https://github.com/intel/ipu6-drivers/pull/310

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