Re: When it rains it pours

["Limonciello, Mario" <mario.limonciello@amd.com>]

On 6/30/2023 14:39, Bjorn Helgaas wrote:
> On Fri, Jun 30, 2023 at 02:30:56PM -0500, Limonciello, Mario wrote:
>> 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.
> 
> I think we can do that.  But the patch is already in the pull request
> for v6.5, so we'll have to wait until Linus pulls it and then ask the
> stable folks to pick it up.  I don't think it should be a big deal; we
> just need a mainline SHA1 for it.
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/stable-kernel-rules.rst?id=v6.4#n64

OK thanks, I saw your PR was sent out but I didn't realize it wasn't 
picked yet.

I'll keep an eye out for when the SHA1 is in Linus' tree and I'll 
request it for stable when it is.