linux-kernel - Re: [PATCH v3 13/22] ACPI: platform_profile: Require handlers to support balanced profile

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Message-ID: <62756516-21cf-49c8-851f-f7fe3a0b0345@gmx.de>
Date: Thu, 31 Oct 2024 22:01:27 +0100
From: Armin Wolf <W_Armin@....de>
To: Mario Limonciello <mario.limonciello@....com>,
 Hans de Goede <hdegoede@...hat.com>,
 Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Cc: "Rafael J . Wysocki" <rafael@...nel.org>, Len Brown <lenb@...nel.org>,
 Maximilian Luz <luzmaximilian@...il.com>, Lee Chun-Yi <jlee@...e.com>,
 Shyam Sundar S K <Shyam-sundar.S-k@....com>,
 Corentin Chary <corentin.chary@...il.com>, "Luke D . Jones"
 <luke@...nes.dev>, Ike Panhc <ike.pan@...onical.com>,
 Henrique de Moraes Holschuh <hmh@....eng.br>,
 Alexis Belmonte <alexbelm48@...il.com>,
 Uwe Kleine-König <u.kleine-koenig@...gutronix.de>,
 Ai Chao <aichao@...inos.cn>, Gergo Koteles <soyer@....hu>,
 open list <linux-kernel@...r.kernel.org>,
 "open list:ACPI" <linux-acpi@...r.kernel.org>,
 "open list:MICROSOFT SURFACE PLATFORM PROFILE DRIVER"
 <platform-driver-x86@...r.kernel.org>,
 "open list:THINKPAD ACPI EXTRAS DRIVER"
 <ibm-acpi-devel@...ts.sourceforge.net>,
 Mark Pearson <mpearson-lenovo@...ebb.ca>,
 Matthew Schwartz <matthew.schwartz@...ux.dev>
Subject: Re: [PATCH v3 13/22] ACPI: platform_profile: Require handlers to
 support balanced profile

Am 31.10.24 um 21:43 schrieb Mario Limonciello:

> On 10/31/2024 15:39, Armin Wolf wrote:
>> Am 31.10.24 um 05:09 schrieb Mario Limonciello:
>>
>>> As support for multiple simultaneous platform handers is introduced
>>> it's
>>> important they have at least the balanced profile in common.
>>>
>>> This will be used as a fallback in case setting the profile across
>>> one of the
>>> handlers happens to fail.
>>
>> Do we actually need this patch anymore now that we have the "custom"
>> platform profile?
>> If setting the platform profile fails for some handlers, then we
>> simply display the current
>> platform profile as "custom".
>
> Yes; it's still needed because 'balanced' is used as the fallback of
> something failed.  If you fail to write to a handler it gets you back
> to a known place for all GPUs.
>
> Now I suppose it's up for discussion if that's really the right thing
> to do.
>
> Maybe because of custom we don't even need that.
>
> If I have 3 profile handlers in
> low-power
> balanced
> balanced
>
> IE I'm already in 'custom'.
>
> If I try to write performance and the first two succeed but the third
> fails what's better:
>
> performance
> performance
> balanced
>
> Or
>
> balanced
> balanced
> balanced
>
I think the first is better, as we cannot really guarantee that setting "balanced" for all handlers
will always work.

Thanks,
Armin Wolf

>>
>> Thanks,
>> Armin Wolf
>>
>>> Tested-by: Matthew Schwartz <matthew.schwartz@...ux.dev>
>>> Suggested-by: Hans de Goede <hdegoede@...hat.com>
>>> Signed-off-by: Mario Limonciello <mario.limonciello@....com>
>>> ---
>>>   drivers/acpi/platform_profile.c | 4 ++++
>>>   1 file changed, 4 insertions(+)
>>>
>>> diff --git a/drivers/acpi/platform_profile.c b/drivers/acpi/
>>> platform_profile.c
>>> index b70ceb11947d0..57c66d7dbf827 100644
>>> --- a/drivers/acpi/platform_profile.c
>>> +++ b/drivers/acpi/platform_profile.c
>>> @@ -164,6 +164,10 @@ int platform_profile_register(struct
>>> platform_profile_handler *pprof)
>>>           pr_err("platform_profile: handler is invalid\n");
>>>           return -EINVAL;
>>>       }
>>> +    if (!test_bit(PLATFORM_PROFILE_BALANCED, pprof->choices)) {
>>> +        pr_err("platform_profile: handler does not support balanced
>>> profile\n");
>>> +        return -EINVAL;
>>> +    }
>>>       if (!pprof->dev) {
>>>           pr_err("platform_profile: handler device is not set\n");
>>>           return -EINVAL;
>