Re: [PATCH v3 1/3] HID: asus: export asus_hid_fnlock_set() for direct fn-lock control

["Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>]

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On Thu, 7 May 2026, Marcus Grenängen wrote:

> Some ASUS platforms cannot control fn-lock via WMI DEVS and must send a
> HID feature report directly to the N-Key keyboard device instead.
> 
> Add a module-level fnlock_hdev pointer (protected by a mutex) that is set
> at probe time for devices with QUIRK_HID_FN_LOCK and cleared at remove.
> Export asus_hid_fnlock_set(bool) so that asus-armoury can call into
> hid-asus without a circular dependency.
> 
> Signed-off-by: Marcus Grenängen <marcus@grenangen.se>
> ---
>  drivers/hid/hid-asus.c                     | 44 +++++++++++++++++++++-
>  include/linux/platform_data/x86/asus-wmi.h | 15 ++++++++
>  2 files changed, 58 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/hid/hid-asus.c b/drivers/hid/hid-asus.c
> index d34d74df3dc0..402ba9d5e982 100644
> --- a/drivers/hid/hid-asus.c
> +++ b/drivers/hid/hid-asus.c
> @@ -584,6 +584,39 @@ static void asus_sync_fn_lock(struct work_struct *work)
>  	asus_kbd_set_fn_lock(drvdata->hdev, drvdata->fn_lock);
>  }
>  
> +/*
> + * Module-level reference to the HID device that handles fn-lock via feature
> + * report. Set at probe and cleared at remove for QUIRK_HID_FN_LOCK devices.
> + * Protected by fnlock_hdev_lock.
> + */
> +static DEFINE_MUTEX(fnlock_hdev_lock);
> +static struct hid_device *fnlock_hdev;
> +
> +/**
> + * asus_hid_fnlock_set() - Set fn-lock state directly via HID feature report.
> + * @enabled: true to lock fn (F1-F12 primary), false to unlock.
> + *
> + * Called by asus-armoury on platforms where the WMI DEVS path for fn-lock is
> + * non-functional (e.g. ASUS ProArt P16, N-Key keyboard product ID 0x19B6).
> + *
> + * Returns: 0 on success, -ENODEV if no fn-lock capable HID device is present.
> + */
> +int asus_hid_fnlock_set(bool enabled)
> +{
> +	int ret;
> +
> +	guard(mutex)(&fnlock_hdev_lock);
> +	if (!fnlock_hdev)
> +		return -ENODEV;
> +
> +	ret = asus_kbd_set_fn_lock(fnlock_hdev, enabled);
> +	if (ret < 0)
> +		return ret;
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(asus_hid_fnlock_set);
> +
>  static void asus_schedule_work(struct asus_kbd_leds *led)
>  {
>  	unsigned long flags;
> @@ -969,6 +1002,8 @@ static int asus_input_configured(struct hid_device *hdev, struct hid_input *hi)
>  		drvdata->fn_lock = true;
>  		INIT_WORK(&drvdata->fn_lock_sync_work, asus_sync_fn_lock);
>  		asus_kbd_set_fn_lock(hdev, true);
> +		guard(mutex)(&fnlock_hdev_lock);
> +		fnlock_hdev = hdev;
>  	}
>  
>  	if (drvdata->tp) {
> @@ -1008,6 +1043,8 @@ static int asus_input_configured(struct hid_device *hdev, struct hid_input *hi)
>  		drvdata->fn_lock = true;
>  		INIT_WORK(&drvdata->fn_lock_sync_work, asus_sync_fn_lock);
>  		asus_kbd_set_fn_lock(hdev, true);
> +		guard(mutex)(&fnlock_hdev_lock);
> +		fnlock_hdev = hdev;

What's going on with this patch? Why this context appears more than once 
on different lines???

I even wasted my time on checking what hid tree has queued, and came up 
zero explanation (as expected).

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 i.