Re: linux-6.6.y: Regression in amd-pstate cpufreq driver since 6.6.34

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

On 7/1/2024 11:13, Lars Wendler wrote:
> Hello Mario,
> 
> Am Mon, 1 Jul 2024 10:58:17 -0500
> schrieb Mario Limonciello <mario.limonciello@amd.com>:
> 
>>> I've tested both, 6.9.7 and 6.10-rc6 and they both don't have that
>>> issue. I can disable CPU boost with both kernel versions.
>>
>> Thanks for checking those.  That's good to hear it's only an issue in
>> the LTS series.
>>
>> It means we have the option to either drop that patch from LTS kernel
>> series or identify the other commit(s) that helped it.
>>
>> Can you see if adding this commit to 6.6.y helps you?
>>
>> https://git.kernel.org/superm1/c/8164f743326404fbe00a721a12efd86b2a8d74d2
> 
> that commit does not fix the regression.
> 

I think I might have found the issue.

With that commit backported on 6.6.y in amd_pstate_set_boost() the 
policy max frequency is nominal  *1000 [1].

However amd_get_nominal_freq() already returns nominal *1000 [2].

If you compare on 6.9 get_nominal_freq() doesn't return * 1000 [3].

So the patch only makes sense on 6.9 and later.

We should revert it in 6.6.y.



Greg,


Can you please revert 8f893e52b9e0 ("cpufreq: amd-pstate: Fix the 
inconsistency in max frequency units") in 6.6.y?


[1] 
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/drivers/cpufreq/amd-pstate.c?h=linux-6.6.y#n678
[2] 
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/drivers/cpufreq/amd-pstate.c?h=linux-6.6.y#n637
[3] 
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/drivers/cpufreq/amd-pstate.c?h=linux-6.9.y#n703