Intel GuC Firmware Fix Submitted For Linux 5.19

Sent in on Friday night were this week's batch of Direct Rendering Manager (DRM) driver fixes for Linux 5.19-rc8 due out on Sunday. While usually the late-stage changes tend to be not too eventful, this pull does carry some extra interest since it does fix the Intel GuC firmware breakage I wrote about last week that ended up breaking Alder Lake P graphics on Linux 5.19 unless also upgrading the firmware version.

As part of this week's Linux 5.19-rc8 DRM fixes is a fix for the Intel GuC firmware breakage that back during the Linux 5.19 merge window the Intel engineers bumped their GuC firmware requirement to version 70 while removing version 69 support. That breakage became apparent during my Intel Alder Lake P testing with the GuC firmware now being required. However, breaking user-space support is frowned upon by upstream developers.

The GuC'ed up state for Intel ADL-P is now fixed for Sunday's Linux 5.19-rc8 release, ahead of Linux 5.19 stable next weekend.

Following last week's article about the Linux 5.19 Alder Lake P graphics acceleration breakage due to upping the firmware requirement, DRM subsystem maintainer David Airlie called on Intel to address this fundamental issue of firmware breakage for production hardware.

Worked out this week was a change to allow GuC 69 firmware to be supported in parallel to GuC 70. Thus with Linux 5.19-rc8 and beyond, GuC 69 firmware will continue to work for allowing Alder Lake P graphics acceleration rather than just breaking if not having version 70.

Intel is now expected to properly maintain GuC firmware compatibility moving forward. Airlie has also laid out new, clear guidelines around Linux firmware support requirements to try to avoid such issues from coming up in the future with developers breaking firmware compatibility for stable drivers/hardware.

Hi Linus,

Fixes for this week. The main one is the i915 firmware fix for the phoronix reported issue. I've written some firmware guidelines as a result, should land in -next soon. Otherwise a few amdgpu fixes, a scheduler fix, ttm fix and two other minor ones.

Regards,
Dave.

More details within this pull.