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Date:   Fri, 31 Mar 2023 11:42:30 +0530
From:   Wyes Karny <wyes.karny@amd.com>
To:     "Rafael J. Wysocki" <rafael@kernel.org>
Cc:     viresh.kumar@linaro.org, ray.huang@amd.com,
        linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org,
        Alexey Kardashevskiy <aik@amd.com>,
        Mario Limonciello <mario.limonciello@amd.com>,
        Perry Yuan <Perry.Yuan@amd.com>
Subject: Re: [PATCH] amd-pstate: Fix amd_pstate mode switch
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References: <20230330141314.1364083-1-wyes.karny@amd.com>
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Hi Rafael,

On 30 Mar 20:19, Rafael J. Wysocki wrote:
> On Thu, Mar 30, 2023 at 4:13 PM Wyes Karny <wyes.karny@amd.com> wrote:
> >
> > amd_pstate mode can be changed by writing the mode name to the `status`
> > sysfs. But some combinations are not working. Fix this issue by taking
> > care of the edge cases.
> >
> > Before the fix the mode change combination test fails:
> >
> >  #./pst_test.sh
> > Test passed: from: disable, to
> > Test passed: from: disable, to disable
> > Test failed: 1, From mode: disable, to mode: passive
> > Test failed: 1, From mode: disable, to mode: active
> > Test failed: 1, From mode: passive, to mode: active
> > Test passed: from: passive, to disable
> > Test failed: 1, From mode: passive, to mode: passive
> > Test failed: 1, From mode: passive, to mode: active
> > Test failed: 1, From mode: active, to mode: active
> > Test passed: from: active, to disable
> > Test failed: 1, From mode: active, to mode: passive
> > Test failed: 1, From mode: active, to mode: active
> >
> > After the fix test passes:
> >
> >  #./pst_test.sh
> > Test passed: from: disable, to
> > Test passed: from: disable, to disable
> > Test passed: from: disable, to passive
> > Test passed: from: disable, to active
> > Test passed: from: passive, to active
> > Test passed: from: passive, to disable
> > Test passed: from: passive, to passive
> > Test passed: from: passive, to active
> > Test passed: from: active, to active
> > Test passed: from: active, to disable
> > Test passed: from: active, to passive
> > Test passed: from: active, to active
> >
> > Fixes: abd61c08ef349 ("cpufreq: amd-pstate: add driver working mode switch support")
> >
> > Acked-by: Huang Rui <ray.huang@amd.com>
> > Reviewed-by: Alexey Kardashevskiy <aik@amd.com>
> > Signed-off-by: Wyes Karny <wyes.karny@amd.com>
> >
> > Cc: "Rafael J. Wysocki" <rafael@kernel.org>
> > Cc: Viresh Kumar <viresh.kumar@linaro.org>
> > Cc: Mario Limonciello <mario.limonciello@amd.com>
> > Cc: Perry Yuan <Perry.Yuan@amd.com>
> 
> This is all fine, but you need to tell me how it interacts with the
> amd-pstate changes in linux-next.
> 
> Does it affect the code in linux-next at all or is it only for 6.3-rc?
> 

This is only for 6.3-rc.
The commit 3ca7bc818d8c ("cpufreq: amd-pstate: Add guided mode control
support via sysfs") in linux-next may not apply cleanly after this fix.
Please let me know if I need to rebase and send the guided mode patches [1].

[1]: https://lore.kernel.org/linux-pm/20230307112740.132338-1-wyes.karny@amd.com/

Thanks,
Wyes
> > ---
> >  drivers/cpufreq/amd-pstate.c | 18 ++++++++----------
> >  1 file changed, 8 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> > index 73c7643b2697..8dd46fad151e 100644
> > --- a/drivers/cpufreq/amd-pstate.c
> > +++ b/drivers/cpufreq/amd-pstate.c
> > @@ -840,22 +840,20 @@ static int amd_pstate_update_status(const char *buf, size_t size)
> >
> >         switch(mode_idx) {
> >         case AMD_PSTATE_DISABLE:
> > -               if (!current_pstate_driver)
> > -                       return -EINVAL;
> > -               if (cppc_state == AMD_PSTATE_ACTIVE)
> > -                       return -EBUSY;
> > -               cpufreq_unregister_driver(current_pstate_driver);
> > -               amd_pstate_driver_cleanup();
> > +               if (current_pstate_driver) {
> > +                       cpufreq_unregister_driver(current_pstate_driver);
> > +                       amd_pstate_driver_cleanup();
> > +               }
> >                 break;
> >         case AMD_PSTATE_PASSIVE:
> >                 if (current_pstate_driver) {
> >                         if (current_pstate_driver == &amd_pstate_driver)
> >                                 return 0;
> >                         cpufreq_unregister_driver(current_pstate_driver);
> > -                       cppc_state = AMD_PSTATE_PASSIVE;
> > -                       current_pstate_driver = &amd_pstate_driver;
> >                 }
> >
> > +               current_pstate_driver = &amd_pstate_driver;
> > +               cppc_state = AMD_PSTATE_PASSIVE;
> >                 ret = cpufreq_register_driver(current_pstate_driver);
> >                 break;
> >         case AMD_PSTATE_ACTIVE:
> > @@ -863,10 +861,10 @@ static int amd_pstate_update_status(const char *buf, size_t size)
> >                         if (current_pstate_driver == &amd_pstate_epp_driver)
> >                                 return 0;
> >                         cpufreq_unregister_driver(current_pstate_driver);
> > -                       current_pstate_driver = &amd_pstate_epp_driver;
> > -                       cppc_state = AMD_PSTATE_ACTIVE;
> >                 }
> >
> > +               current_pstate_driver = &amd_pstate_epp_driver;
> > +               cppc_state = AMD_PSTATE_ACTIVE;
> >                 ret = cpufreq_register_driver(current_pstate_driver);
> >                 break;
> >         default:
> > --
> > 2.34.1
> >