linux-kernel - Re: [PATCH v8 0/8] AMD Pstate Fixes And Enhancements

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Date: Tue, 19 Mar 2024 13:37:53 +0800
From: Huang Rui <ray.huang@....com>
To: "Rafael J. Wysocki" <rafael@...nel.org>
Cc: "Yuan, Perry" <Perry.Yuan@....com>,
	"Limonciello, Mario" <Mario.Limonciello@....com>,
	"Shenoy, Gautham Ranjal" <gautham.shenoy@....com>,
	"rafael.j.wysocki@...el.com" <rafael.j.wysocki@...el.com>,
	"viresh.kumar@...aro.org" <viresh.kumar@...aro.org>,
	"Petkov, Borislav" <Borislav.Petkov@....com>,
	"Deucher, Alexander" <Alexander.Deucher@....com>,
	"Huang, Shimmer" <Shimmer.Huang@....com>,
	"Du, Xiaojian" <Xiaojian.Du@....com>,
	"Meng, Li (Jassmine)" <Li.Meng@....com>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v8 0/8] AMD Pstate Fixes And Enhancements

On Mon, Mar 18, 2024 at 08:49:55PM +0800, Rafael J. Wysocki wrote:
> On Mon, Mar 18, 2024 at 10:48 AM Perry Yuan <perry.yuan@....com> wrote:
> >
> > The patch series adds some fixes and enhancements to the AMD pstate
> > driver.
> > It enables CPPC v2 for certain processors in the family 17H, as
> > requested
> > by TR40 processor users who expect improved performance and lower system
> > temperature.
> >
> > Additionally, it fixes the initialization of nominal_freq for each
> > cpudata
> > and changes latency and delay values to be read from platform firmware
> > firstly
> > for more accurate timing.
> >
> > A new quirk is also added for legacy processors that lack CPPC
> > capabilities which caused the pstate driver to fail loading.
> >
> > Testing done with one APU system while cpb boost on:
> >
> > amd_pstate_lowest_nonlinear_freq:1701000
> > amd_pstate_max_freq:3501000
> > cpuinfo_max_freq:3501000
> > cpuinfo_min_freq:400000
> > scaling_cur_freq:3084836
> > scaling_max_freq:3501000
> > scaling_min_freq:400000
> >
> > analyzing CPU 6:
> >   driver: amd-pstate-epp
> >   CPUs which run at the same hardware frequency: 6
> >   CPUs which need to have their frequency coordinated by software: 6
> >   maximum transition latency:  Cannot determine or is not supported.
> >   hardware limits: 400 MHz - 3.50 GHz
> >   available cpufreq governors: performance powersave
> >   current policy: frequency should be within 400 MHz and 3.50 GHz.
> >                   The governor "powersave" may decide which speed to use
> >                   within this range.
> >   current CPU frequency: Unable to call hardware
> >   current CPU frequency: 3.50 GHz (asserted by call to kernel)
> >   boost state support:
> >     Supported: yes
> >     Active: yes
> >     AMD PSTATE Highest Performance: 255. Maximum Frequency: 3.50 GHz.
> >     AMD PSTATE Nominal Performance: 204. Nominal Frequency: 2.80 GHz.
> >     AMD PSTATE Lowest Non-linear Performance: 124. Lowest Non-linear Frequency: 1.70 GHz.
> >     AMD PSTATE Lowest Performance: 30. Lowest Frequency: 400 MHz.
> >
> > If someone would like to test this patchset, it would need to apply
> > another patchset on top of this in case of some unexpected issue found.
> >
> > https://lore.kernel.org/lkml/cover.1707297581.git.perry.yuan@amd.com/
> > It implements the amd pstate cpb boost feature
> > the below patch link is old version, please apply the latest version
> > while you start the testing work.
> >
> > I would greatly appreciate any feedbacks.
> 
> There are missing changelogs and S-o-b tags in a few messages in this series.
> 
> Overall, I would like someone, preferably at AMD, to take
> responsibility for the amd-pstate driver, review patches modifying it
> and ACK the approved ones.
> 
> Huang Rui, who is listed in MAINTAINERS as the official maintainer of
> it, does not seem to be interested in it any more.
> 
> Can this be addressed, please?

Hi Rafael,

Sorry, I was occupied by other task a couple of months ago. I will talk
with AMD colleagues and figure out the way to make sure the amd-pstate
patches will be actively reviewed and tested. Will give you the feedback.

Thanks,
Ray