linux-kernel - Re: [PATCH v4 13/20] ACPI: platform_profile: Notify change events on register and unregister

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Message-ID: <31247970-55b7-4952-a802-a0e2069c1c6d@amd.com>
Date: Wed, 6 Nov 2024 13:44:28 -0600
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 v4 13/20] ACPI: platform_profile: Notify change events on
 register and unregister

On 11/6/2024 13:40, Armin Wolf wrote:
> Am 05.11.24 um 16:33 schrieb Mario Limonciello:
> 
>> As multiple platform profile handlers may come and go, send a 
>> notification
>> to userspace each time that a platform profile handler is registered or
>> unregistered.
>>
>> Tested-by: Matthew Schwartz <matthew.schwartz@...ux.dev>
>> Reviewed-by: Mark Pearson <mpearson-lenovo@...ebb.ca>
>> Signed-off-by: Mario Limonciello <mario.limonciello@....com>
>> ---
>>   drivers/acpi/platform_profile.c | 5 ++++-
>>   1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/acpi/platform_profile.c b/drivers/acpi/ 
>> platform_profile.c
>> index 79083d0bb22e3..c9917daf683cb 100644
>> --- a/drivers/acpi/platform_profile.c
>> +++ b/drivers/acpi/platform_profile.c
>> @@ -404,6 +404,7 @@ int platform_profile_register(struct 
>> platform_profile_handler *pprof)
>>       if (IS_ERR(pprof->class_dev))
>>           return PTR_ERR(pprof->class_dev);
>>       dev_set_drvdata(pprof->class_dev, pprof);
>> +    sysfs_notify(acpi_kobj, NULL, "platform_profile");
>>
>>       cur_profile = pprof;
>>       return 0;
>> @@ -419,7 +420,9 @@ int platform_profile_remove(struct 
>> platform_profile_handler *pprof)
>>   {
>>       guard(mutex)(&profile_lock);
>>
>> -    sysfs_remove_group(acpi_kobj, &platform_profile_group);
> 
> When do we remove platform_profile_group now?
> 

When incorporating your other feedback I noticed this was still there 
and it will be removed for the next revision.

The idea will be as soon as a class registers the legacy interface is 
created and will stay for the lifetime of the boot.

If all drivers are unloaded it will return -EINVAL until a new driver is 
loaded.

> Thanks,
> Armin Wolf
> 
>> +    cur_profile = NULL;
>> +
>> +    sysfs_notify(acpi_kobj, NULL, "platform_profile");
>>
>>       device_destroy(&platform_profile_class, MKDEV(0, pprof->minor));
>>