linux-kernel - Re: [PATCH v7 14/22] ACPI: platform_profile: Notify change events on register and unregister

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Message-ID: <99c47bd4-02f4-46bc-a355-50a0ab1d8538@gmx.de>
Date: Thu, 21 Nov 2024 23:24:52 +0100
From: Armin Wolf <W_Armin@....de>
To: Mario Limonciello <mario.limonciello@....com>,
 Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Cc: Hans de Goede <hdegoede@...hat.com>,
 "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 v7 14/22] ACPI: platform_profile: Notify change events on
 register and unregister

Am 20.11.24 um 16:37 schrieb Mario Limonciello:

> On 11/20/2024 09:09, Ilpo Järvinen wrote:
>> On Tue, 19 Nov 2024, Mario Limonciello wrote:
>>
>>> 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.
>>>
>>> Reviewed-by: Armin Wolf <W_Armin@....de>
>>> Tested-by: Mark Pearson <mpearson-lenovo@...ebb.ca>
>>> Tested-by: Matthew Schwartz <matthew.schwartz@...ux.dev>
>>> Reviewed-by: Mark Pearson <mpearson-lenovo@...ebb.ca>
>>> Signed-off-by: Mario Limonciello <mario.limonciello@....com>
>>> ---
>>> v7:
>>>   * Add Armin's tag
>>> ---
>>>   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 1530e6096cd39..de0804305b02c 100644
>>> --- a/drivers/acpi/platform_profile.c
>>> +++ b/drivers/acpi/platform_profile.c
>>> @@ -363,6 +363,8 @@ int platform_profile_register(struct
>>> platform_profile_handler *pprof)
>>>           goto cleanup_ida;
>>>       }
>>>   +    sysfs_notify(acpi_kobj, NULL, "platform_profile");
>>> +
>>>       cur_profile = pprof;
>>>         err = sysfs_update_group(acpi_kobj, &platform_profile_group);
>>
>> Is the ordering problematic here, how long userspace has to wait for the
>> update to become visible?
>
> TBH - this feels like an artifact of the earlier patches.  I don't
> know that we really need the notify anymore since calling
> sysfs_update_group().
>
> I'm tending to think drop this patch entirely.
>
I do not think so. A new platform profile handler might cause the platform profile choices to change. It might also cause the platform profile
to switch to "custom" in some cases. So i think we still have to keep this patch.

Thanks

>>
>>> @@ -393,6 +395,8 @@ int platform_profile_remove(struct
>>> platform_profile_handler *pprof)
>>>       device_unregister(pprof->class_dev);
>>>       ida_free(&platform_profile_ida, id);
>>>   +    sysfs_notify(acpi_kobj, NULL, "platform_profile");
>>> +
>>>       sysfs_update_group(acpi_kobj, &platform_profile_group);
>>
>>
>
>