AMD Zen 3 APU Temperature Monitoring Narrowly Misses Linux 5.14

Landing into "hwmon-next" just after the Linux 5.14-rc1 tagging that marks the formal end to feature work for the current cycle was the k10temp driver adding support for AMD Zen 3 APU temperature monitoring under Linux.

The k10temp driver already has support for Zen 3 desktop CPUs and even Zen 3 SP3/Threadripper CPUs with the necessary model IDs in place, but unfortunately the Zen 3 Ryzen APU model ID was missing until the commit on late Sunday.

The change is rather trivial and namely just adding the Family 19h Model 50 bits in place for allowing this k10temp thermal driver to work for Zen 3 APUs.

Zen 3 APU temperature monitoring makes it to hwmon-next.

The patch is small enough that it could be submitted as a "fix" so early in the Linux 5.14 cycle, but as of writing it's only in "hwmon-next" and not marked for stable or submitted as a pull request for 5.14 mainline. Thus this temperature reporting might not appear until Linux 5.15. The patch for k10temp was posted back in May but from the hwmon side was held up by needing this patch with the IDs that worked its way in through the TIP branch.

This k10temp addition didn't come from AMD engineers but rather an end-user after presumably getting his hands on one of the Zen 3 APUs so far to market and finding the Linux temperature reporting not working. It's a pity such a mundane patch didn't work its way into the Linux kernel months ago - even before launch - for such a basic feature but for areas like k10temp it generally hasn't been a focus by AMD and left up to the community.