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

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

In the future, please send this to the regressions M/L and CC people 
instead of just sending a private message.

For now, I've added the @regressions and @stable mailing lists as this 
is an issue you find exposed specifically in the LTS series.

Hi Lars,

Can you please test 6.9.7?  If this is still failing, can you please 
check 6.10-rc6?

I'd like to understand if we just have a missing commit to backport or 
it's a problem in the mainline kernel as well.

 From the below description it's specifically with boost in passive 
mode, right?

If 6.10-rc6 is still affected, can you please see if this commit helps?
https://git.kernel.org/pub/scm/linux/kernel/git/superm1/linux.git/commit/?h=linux-next&id=e8f555daacd3377bf691fdda2490c0b164e00085

This is going into 6.11-rc1.

Perry, Jassmine,

Can you try to repro this using bleeding-edge or linux-next branches?

Thanks,

On 7/1/2024 4:33, Huang, Ray wrote:
> [AMD Official Use Only - AMD Internal Distribution Only]
> 
> Hi all,
> 
> Could you please help for a quick fix?
> 
> -----Original Message-----
> From: Lars Wendler <wendler.lars@web.de>
> Sent: Monday, July 1, 2024 5:30 PM
> To: Huang, Ray <Ray.Huang@amd.com>
> Cc: gregkh@linuxfoundation.org
> Subject: linux-6.6.y: Regression in amd-pstate cpufreq driver since 6.6.34
> 
> Hello dear kernel developers,
> 
> I might have found a regression in the amd-pstate driver of linux-6.6 stable series. I haven't checked linux-master nor any other LTS branch.
> 
> 
> Now here's what I have found:
> 
> Since linux-6.6.34 the following command fails:
> 
>    # echo 0 > /sys/devices/system/cpu/cpufreq/boost
>      -bash: echo: write error: Invalid argument
> 
> and indeed, disabling CPU boost seems to not work:
> 
>    # cat /sys/devices/system/cpu/cpufreq/boost
>    1
> 
> I have bisected the issue to commit
> 8f893e52b9e030a25ea62e31271bf930b01f2f07:
> 
>    cpufreq: amd-pstate: Fix the inconsistency in max frequency units
> 
>    commit e4731baaf29438508197d3a8a6d4f5a8c51663f8 upstream.
> 
> Reverting that commit (even on latest linux-6.6 release) gives me back the ability to disable CPU boost again.
> 
> I can only reproduce this bug on my Zen4 machine:
> 
>    # lscpu | grep "^Model name:" | sed 's@[[:space:]][[:space:]]\+@ @'
>    Model name: AMD Ryzen 7 7745HX with Radeon Graphics
> 
> My older Zen3 machines seem not to be affected by this issue. All my Ryzen systems run on latest linux-6.6 kernels and have the following configuration regarding amd-pstate:
> 
>    # zgrep -F AMD_PSTATE /proc/config.gz
>    CONFIG_X86_AMD_PSTATE=y
>    CONFIG_X86_AMD_PSTATE_DEFAULT_MODE=2
>    # CONFIG_X86_AMD_PSTATE_UT is not set
> 
> 
> If you need more information, please don't hesitate to ask.
> 
> Kind regards
> Lars Wendler