Re: [PATCH v2 1/1] ACPI: platform_profile: Treat quiet and low power the same

["Kurt Borja" <kuurtb@gmail.com>]

On Tue Mar 4, 2025 at 8:32 AM -05, Antheas Kapenekakis wrote:
> On Tue, 4 Mar 2025 at 14:28, Kurt Borja <kuurtb@gmail.com> wrote:
>>
>> Hi all,
>>
>> On Tue Mar 4, 2025 at 7:49 AM -05, Mario Limonciello wrote:
>> >
>> >
>> > On 3/4/25 02:38, Antheas Kapenekakis wrote:
>> >> On Tue, 4 Mar 2025 at 07:48, Mario Limonciello <superm1@kernel.org> wrote:
>> >>>
>> >>> From: Mario Limonciello <mario.limonciello@amd.com>
>> >>>
>> >>> When two drivers don't support all the same profiles the legacy interface
>> >>> only exports the common profiles.
>> >>>
>> >>> This causes problems for cases where one driver uses low-power but another
>> >>> uses quiet because the result is that neither is exported to sysfs.
>> >>>
>> >>> If one platform profile handler supports quiet and the other
>> >>> supports low power treat them as the same for the purpose of
>> >>> the sysfs interface.
>> >>>
>> >>> Fixes: 688834743d67 ("ACPI: platform_profile: Allow multiple handlers")
>> >>> Reported-by: Antheas Kapenekakis <lkml@antheas.dev>
>> >>> Closes: https://lore.kernel.org/platform-driver-x86/e64b771e-3255-42ad-9257-5b8fc6c24ac9@gmx.de/T/#mc068042dd29df36c16c8af92664860fc4763974b
>> >>> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
>> >>> ---
>> >>>   drivers/acpi/platform_profile.c | 38 ++++++++++++++++++++++++++++++---
>> >>>   1 file changed, 35 insertions(+), 3 deletions(-)
>> >>>
>> >>> diff --git a/drivers/acpi/platform_profile.c b/drivers/acpi/platform_profile.c
>> >>> index 2ad53cc6aae53..d9a7cc5891734 100644
>> >>> --- a/drivers/acpi/platform_profile.c
>> >>> +++ b/drivers/acpi/platform_profile.c
>> >>> @@ -73,8 +73,20 @@ static int _store_class_profile(struct device *dev, void *data)
>> >>>
>> >>>          lockdep_assert_held(&profile_lock);
>> >>>          handler = to_pprof_handler(dev);
>> >>> -       if (!test_bit(*bit, handler->choices))
>> >>> -               return -EOPNOTSUPP;
>> >>> +       if (!test_bit(*bit, handler->choices)) {
>> >>> +               switch (*bit) {
>> >>> +               case PLATFORM_PROFILE_QUIET:
>> >>> +                       *bit = PLATFORM_PROFILE_LOW_POWER;
>> >>> +                       break;
>> >>> +               case PLATFORM_PROFILE_LOW_POWER:
>> >>> +                       *bit = PLATFORM_PROFILE_QUIET;
>> >>> +                       break;
>> >>> +               default:
>> >>> +                       return -EOPNOTSUPP;
>> >>> +               }
>> >>> +               if (!test_bit(*bit, handler->choices))
>> >>> +                       return -EOPNOTSUPP;
>> >>> +       }
>> >>>
>> >>>          return handler->ops->profile_set(dev, *bit);
>> >>>   }
>> >>> @@ -252,8 +264,16 @@ static int _aggregate_choices(struct device *dev, void *data)
>> >>>          handler = to_pprof_handler(dev);
>> >>>          if (test_bit(PLATFORM_PROFILE_LAST, aggregate))
>> >>>                  bitmap_copy(aggregate, handler->choices, PLATFORM_PROFILE_LAST);
>> >>> -       else
>> >>> +       else {
>> >>> +               /* treat quiet and low power the same for aggregation purposes */
>> >>> +               if (test_bit(PLATFORM_PROFILE_QUIET, handler->choices) &&
>> >>> +                   test_bit(PLATFORM_PROFILE_LOW_POWER, aggregate))
>> >>> +                       set_bit(PLATFORM_PROFILE_QUIET, aggregate);
>> >>> +               else if (test_bit(PLATFORM_PROFILE_LOW_POWER, handler->choices) &&
>> >>> +                        test_bit(PLATFORM_PROFILE_QUIET, aggregate))
>> >>> +                       set_bit(PLATFORM_PROFILE_LOW_POWER, aggregate);
>> >>>                  bitmap_and(aggregate, handler->choices, aggregate, PLATFORM_PROFILE_LAST);
>> >>> +       }
>> >>
>> >> So you end up showing both? If that's the case, isn't it equivalent to
>> >> just make amd-pmf show both quiet and low-power?
>> >>
>> >> I guess it is not ideal for framework devices. But if asus devices end
>> >> up showing both, then it should be ok for framework devices to show
>> >> both.
>> >>
>> >> I like the behavior of the V1 personally.
>> >
>> > No; this doesn't cause it to show both.  It only causes one to show up.
>> > I confirmed it with a contrived situation on my laptop that forced
>> > multiple profile handlers that supported a mix.
>> >
>> >
>> > # cat /sys/firmware/acpi/platform_profile*
>> > low-power
>> > low-power balanced performance
>> >
>> > # cat /sys/class/platform-profile/platform-profile-*/profile
>> > quiet
>> > quiet
>> > quiet
>> > quiet
>> > quiet
>> > quiet
>> > quiet
>> > quiet
>> > quiet
>> > quiet
>> > quiet
>> > quiet
>> > quiet
>> > quiet
>> > quiet
>> > quiet
>> > quiet
>> > quiet
>> > quiet
>> > quiet
>> > quiet
>> > quiet
>> > quiet
>> > quiet
>> > low-power
>> >
>> >>
>> >>>          return 0;
>> >>>   }
>> >>> @@ -305,6 +325,13 @@ static int _aggregate_profiles(struct device *dev, void *data)
>> >>>          if (err)
>> >>>                  return err;
>> >>>
>> >>> +       /* treat low-power and quiet as the same */
>> >>> +       if ((*profile == PLATFORM_PROFILE_LOW_POWER &&
>> >>> +            val == PLATFORM_PROFILE_QUIET) ||
>> >>> +           (*profile == PLATFORM_PROFILE_QUIET &&
>> >>> +            val == PLATFORM_PROFILE_LOW_POWER))
>> >>> +               *profile = val;
>> >>> +
>> >>>          if (*profile != PLATFORM_PROFILE_LAST && *profile != val)
>> >>>                  *profile = PLATFORM_PROFILE_CUSTOM;
>> >>>          else
>> >>> @@ -531,6 +558,11 @@ struct device *platform_profile_register(struct device *dev, const char *name,
>> >>>                  dev_err(dev, "Failed to register platform_profile class device with empty choices\n");
>> >>>                  return ERR_PTR(-EINVAL);
>> >>>          }
>> >>> +       if (test_bit(PLATFORM_PROFILE_QUIET, pprof->choices) &&
>> >>> +           test_bit(PLATFORM_PROFILE_LOW_POWER, pprof->choices)) {
>> >>> +               dev_err(dev, "Failed to register platform_profile class device with both quiet and low-power\n");
>> >>> +               return ERR_PTR(-EINVAL);
>> >>> +       }
>> >>
>> >> Can you avoid failing here? It caused a lot of issues in the past (the
>> >> WMI driver bails). a dev_err should be enough. Since you do not fail
>> >> maybe it can be increased to dev_crit.
>> >>
>> >> There is at least one driver that implements both currently, and a fix
>> >> would have to precede this patch.
>> >
>> > Oh, acer-wmi?  Kurt; can you please comment?  Are both simultaneous?
>>
>> There are a few laptops supported by alienware-wmi that definitely have
>> both (including mine). The acer-wmi and the samsung-galaxybook drivers
>> also probe for available choices dynamically, so some of those devices
>> may be affected by this too.
>>
>> So yes, we shouldn't fail registration here.
>>
>> Anyway, I like this approach more than v1. What do you think about
>> constraining this fix to the legacy interface?
>
> AFAIK new interface is ok and should not be modified. None of the
> previous solutions touched it (well, changing quiet to low-power did).
> But I still expect the legacy interface to work the same way on 6.14.

This patch also permanently alias quiet and low-power for the new
interface, if either one is not available.

>
> What happens if there is one handler that does low-power and one that
> does quiet? Is one choice preferred? And then are writes accepted in
> both?
>
> I cannot have the same device requiring low-power and quiet depending
> on kernel version or boot. I do tdp controls per manufacturer.

I'm not sure what you mean here.

-- 
 ~ Kurt

>
>> --
>>  ~ Kurt
>>
>> >
>> >>
>> >>>
>> >>>          guard(mutex)(&profile_lock);
>> >>>
>> >>> --
>> >>> 2.43.0
>> >>>
>>