Hi Bjorn,
For the _REG change that went into Linus' tree I was recently made aware
of another system that it helps.
This system was appearing to hang during bootup which evaluating the
USB4 _OSC.
This hang happened on both the 6.1 LTS kernel and 6.4 final kernel.
In looking at the BIOS debug log shared by the reporter I noticed that
the kernel isn't hung it's just that the BIOS was waiting to be given
the ability to access the config space.
Backporting just that _REG patch onto 6.1 LTS kernel fixes the issue.
I'm encouraging the BIOS team to try to come up with a cleaner failure
path for the lack of _REG being called. However there is always the
possibility they can't or choose not to and people try to boot older
kernels and fail.
Given how severe this boot issue is compared to the original suspend
issue that prompted the patch I wanted to gauge how you feel about the
risk of taking this change back to stable.
Thanks!
