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

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Message-ID: <a95ed9c4-a112-4087-aca9-8323902273b2@amd.com>
Date: Thu, 31 Oct 2024 15:43:45 -0500
From: Mario Limonciello <mario.limonciello@....com>
To: Armin Wolf <W_Armin@....de>, 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

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

> 
> 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;