Re: [PATCH v9 20/22] ACPI: platform_profile: Allow multiple handlers

Ilpo Järvinen
2024-12-05T14:27:14Z

[-- Attachment #1: Type: text/plain, Size: 3230 bytes --]

On Sun, 1 Dec 2024, Mario Limonciello wrote:

> Multiple drivers may attempt to register platform profile handlers,
> but only one may be registered and the behavior is non-deterministic
> for which one wins. It's mostly controlled by probing order.
>
> This can be problematic if one driver changes CPU settings and another
> driver notifies the EC for changing fan curves.
>
> Modify the ACPI platform profile handler to let multiple drivers
> register platform profile handlers and abstract this detail from userspace.
>
> To avoid undefined behaviors only offer profiles that are commonly
> advertised across multiple handlers.
>
> If any problems occur when changing profiles for any driver, then the
> drivers that were already changed remain changed and the legacy sysfs
> handler will report 'custom'.
>
> Tested-by: Mark Pearson <mpearson-lenovo@squebb.ca>
> Tested-by: Matthew Schwartz <matthew.schwartz@linux.dev>
> Reviewed-by: Mark Pearson <mpearson-lenovo@squebb.ca>
> Reviewed-by: Armin Wolf <W_Armin@gmx.de>
> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
> ---
> drivers/acpi/platform_profile.c | 11 -----------
> 1 file changed, 11 deletions(-)
>
> diff --git a/drivers/acpi/platform_profile.c b/drivers/acpi/platform_profile.c
> index 289b5d43638ae..2e38aa410b3ad 100644
> --- a/drivers/acpi/platform_profile.c
> +++ b/drivers/acpi/platform_profile.c
> @@ -10,7 +10,6 @@
> #include <linux/platform_profile.h>
> #include <linux/sysfs.h>
>
> -static struct platform_profile_handler *cur_profile;
> static DEFINE_MUTEX(profile_lock);
>
> static const char * const profile_names[] = {
> @@ -399,8 +398,6 @@ static const struct attribute_group platform_profile_group = {
>
> void platform_profile_notify(struct platform_profile_handler *pprof)
> {
> - if (!cur_profile)
> - return;
> scoped_cond_guard(mutex_intr, return, &profile_lock) {
> _notify_class_profile(pprof->class_dev, NULL);
> }
> @@ -463,9 +460,6 @@ int platform_profile_register(struct platform_profile_handler *pprof)
> }
>
> guard(mutex)(&profile_lock);
> - /* We can only have one active profile */
> - if (cur_profile)
> - return -EEXIST;
>
> /* create class interface for individual handler */
> pprof->minor = ida_alloc(&platform_profile_ida, GFP_KERNEL);
> @@ -481,8 +475,6 @@ int platform_profile_register(struct platform_profile_handler *pprof)
>
> sysfs_notify(acpi_kobj, NULL, "platform_profile");
>
> - cur_profile = pprof;
> -
> err = sysfs_update_group(acpi_kobj, &platform_profile_group);
> if (err)
> goto cleanup_cur;
> @@ -490,7 +482,6 @@ int platform_profile_register(struct platform_profile_handler *pprof)
> return 0;
>
> cleanup_cur:
> - cur_profile = NULL;
> device_unregister(pprof->class_dev);
>
> cleanup_ida:
> @@ -505,8 +496,6 @@ int platform_profile_remove(struct platform_profile_handler *pprof)
> int id;
> guard(mutex)(&profile_lock);
>
> - cur_profile = NULL;
> -
> id = pprof->minor;
> device_unregister(pprof->class_dev);
> ida_free(&platform_profile_ida, id);
>

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

--
i.