On Thu, Oct 31, 2024, at 12:09 AM, 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 revert
> back to the balanced profile, which is now required.
>
> Tested-by: Matthew Schwartz <matthew.schwa...@linux.dev>
> Signed-off-by: Mario Limonciello <mario.limoncie...@amd.com>
> ---
> drivers/acpi/platform_profile.c | 10 ++--------
> 1 file changed, 2 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/acpi/platform_profile.c b/drivers/acpi/platform_profile.c
> index 1cc8182930dde..a845524a248b9 100644
> --- a/drivers/acpi/platform_profile.c
> +++ b/drivers/acpi/platform_profile.c
> @@ -9,7 +9,6 @@
> #include <linux/platform_profile.h>
> #include <linux/sysfs.h>
>
> -static struct platform_profile_handler *cur_profile;
> static LIST_HEAD(platform_profile_handler_list);
> static DEFINE_MUTEX(profile_lock);
>
> @@ -212,7 +211,8 @@ static const struct attribute_group
> platform_profile_group = {
>
> void platform_profile_notify(void)
> {
> - if (!cur_profile)
> + guard(mutex)(&profile_lock);
> + if (!platform_profile_is_registered())
> return;
> sysfs_notify(acpi_kobj, NULL, "platform_profile");
> }
> @@ -280,9 +280,6 @@ 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;
>
> registered = platform_profile_is_registered();
> if (!registered) {
> @@ -313,7 +310,6 @@ int platform_profile_register(struct
> platform_profile_handler *pprof)
> list_add_tail(&pprof->list, &platform_profile_handler_list);
> sysfs_notify(acpi_kobj, NULL, "platform_profile");
>
> - cur_profile = pprof;
> return 0;
>
> cleanup_device:
> @@ -336,8 +332,6 @@ int platform_profile_remove(struct
> platform_profile_handler *pprof)
>
> list_del(&pprof->list);
>
> - cur_profile = NULL;
> -
> sysfs_notify(acpi_kobj, NULL, "platform_profile");
>
> sysfs_remove_group(&pprof->class_dev->kobj, &platform_profile_group);
> --
> 2.43.0
Looks good to me
Reviewed-by: Mark Pearson <mpearson-len...@squebb.ca>
Mark
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