Re: [PATCH v6 0/7] HID: asus: Fix ASUS ROG Laptop's Keyboard backlight handling

Antheas Kapenekakis
2025-10-17T07:54:51Z

On Thu, 16 Oct 2025 at 18:16, Antheas Kapenekakis <lkml@antheas.dev> wrote:
>
> On Thu, 16 Oct 2025 at 17:09, Ilpo Järvinen
> <ilpo.jarvinen@linux.intel.com> wrote:
> >
> > On Thu, 16 Oct 2025, Antheas Kapenekakis wrote:
> > > On Thu, 16 Oct 2025 at 13:57, Denis Benato <benato.denis96@gmail.com> wrote:
> > > > On 10/13/25 22:15, Antheas Kapenekakis wrote:
> > > > > This is a two part series which does the following:
> > > > > - Clean-up init sequence
> > > > > - Unify backlight handling to happen under asus-wmi so that all Aura
> > > > > devices have synced brightness controls and the backlight button works
> > > > > properly when it is on a USB laptop keyboard instead of one w/ WMI.
> > > > >
> > > > > For more context, see cover letter of V1. Since V5, I removed some patches
> > > > > to make this easier to merge.
> > > > >
> > > > > All comments with these patches had been addressed since V4.
> > > > I have loaded this patchset for users of asus-linux project to try out.
> > > >
> > > > One of them opened a bug report about a kernel bug that happens
> > > > consistently when closing the lid of his laptop [1].
> > > >
> > > > He also sent another piece of kernel log, but didn't specify anything more
> > > > about this [2].
> > > >
> > > > [1] https://pastebin.com/akZx1w10
> > > > [2] https://pastebin.com/sKdczPgf
> > >
> > > Can you provide a link to the bug report? [2] seems unrelated.
> > >
> > > As for [1], it looks like a trace that stems from a sysfs write to
> > > brightness stemming from userspace that follows the same chain it
> > > would on a stock kernel and times out. Is it present on a stock
> > > kernel?
> > >
> > > Ilpo should know more about this, could the spinlock be interfering?
> >
> > [1] certainly seems to do schedule() from do_kbd_led_set() so it's not
> > possible to use spinlock there.
> >
> > So we're back to what requires the spinlock? And what the spinlock
> > protects?
>
> For that invocation, since it is coming from the cdev device owned by
> asus_wmi, it protects asus_ref.listeners under do_kbd_led_set.
> asus_wmi is protected by the fact it is owned by that device. Spinlock
> is not required in this invocation due to not being an IRQ.
>
> Under asus_hid_event (second to last patch), which is called from an
> IRQ, a spinlock is required for protecting both listeners and the
> asus_ref.asus, and I suspect that scheduling from an IRQ is not
> allowed either. Is that correct?

So it is a bit tricky here. When the IRQ fires, it needs to know
whether asus-wmi will handle the keyboard brightness event so that it
falls back to emitting it.

If we want it to know for sure, it needs to access asus_wmi, so it
needs a spinlock or an IRQ friendly lock. This way, currently,
asus_hid_event will return -EBUSY if there is no led device so the
event propagates through hid.

If we say that it is good enough to know that it was compiled with
IS_REACHABLE(CONFIG_ASUS_WMI), ie the actual implementation of
asus_hid_event in asus-wmi will never return an error, then,
asus_hid_event can schedule a task to fire the event without a lock,
and that task can use a normal locking primitive.

If the task needs to be assigned to a device or have a handle,
asus_hid_listener can be provided to asus_hid_event, so that it is
owned by the calling device.

What would the appropriate locking primitive be in this case?

> Antheas
> >
> > Not related to this particular email in this thread, if the users are
> > testing something with different kernels, it's also important to make sure
> > that the lockdep configs are enabled in both. As it could be that in one
> > kernel lockdep is not enabled and thus it won't do the splat.
> >
> > --
> > i.
> >
> >
> > > My testing on devices that have WMI led controls is a bit limited
> > > unfortunately. However, most of our asus users have been happy with
> > > this series for around half a year now.
> > >
> > > > > ---
> > > > > V5: https://lore.kernel.org/all/20250325184601.10990-1-lkml@antheas.dev/
> > > > > V4: https://lore.kernel.org/lkml/20250324210151.6042-1-lkml@antheas.dev/
> > > > > V3: https://lore.kernel.org/lkml/20250322102804.418000-1-lkml@antheas.dev/
> > > > > V2: https://lore.kernel.org/all/20250320220924.5023-1-lkml@antheas.dev/
> > > > > V1: https://lore.kernel.org/all/20250319191320.10092-1-lkml@antheas.dev/
> > > > >
> > > > > Changes since V5:
> > > > > - It's been a long time
> > > > > - Remove addition of RGB as that had some comments I need to work on
> > > > > - Remove folio patch (already merged)
> > > > > - Remove legacy fix patch 11 from V4. There is a small chance that
> > > > > without this patch, some old NKEY keyboards might not respond to
> > > > > RGB commands according to Luke, but the kernel driver does not do
> > > > > RGB currently. The 0x5d init is done by Armoury crate software in
> > > > > Windows. If an issue is found, we can re-add it or just remove patches
> > > > > 1/2 before merging. However, init could use the cleanup.
> > > > >
> > > > > Changes since V4:
> > > > > - Fix KConfig (reported by kernel robot)
> > > > > - Fix Ilpo's nits, if I missed anything lmk
> > > > >
> > > > > Changes since V3:
> > > > > - Add initializer for 0x5d for old NKEY keyboards until it is verified
> > > > > that it is not needed for their media keys to function.
> > > > > - Cover init in asus-wmi with spinlock as per Hans
> > > > > - If asus-wmi registers WMI handler with brightness, init the brightness
> > > > > in USB Asus keyboards, per Hans.
> > > > > - Change hid handler name to asus-UNIQ:rgb:peripheral to match led class
> > > > > - Fix oops when unregistering asus-wmi by moving unregister outside of
> > > > > the spin lock (but after the asus reference is set to null)
> > > > >
> > > > > Changes since V2:
> > > > > - Check lazy init succeds in asus-wmi before setting register variable
> > > > > - make explicit check in asus_hid_register_listener for listener existing
> > > > > to avoid re-init
> > > > > - rename asus_brt to asus_hid in most places and harmonize everything
> > > > > - switch to a spinlock instead of a mutex to avoid kernel ooops
> > > > > - fixup hid device quirks to avoid multiple RGB devices while still exposing
> > > > > all input vendor devices. This includes moving rgb init to probe
> > > > > instead of the input_configured callbacks.
> > > > > - Remove fan key (during retest it appears to be 0xae that is already
> > > > > supported by hid-asus)
> > > > > - Never unregister asus::kbd_backlight while asus-wmi is active, as that
> > > > > - removes fds from userspace and breaks backlight functionality. All
> > > > > - current mainline drivers do not support backlight hotplugging, so most
> > > > > userspace software (e.g., KDE, UPower) is built with that assumption.
> > > > > For the Ally, since it disconnects its controller during sleep, this
> > > > > caused the backlight slider to not work in KDE.
> > > > >
> > > > > Changes since V1:
> > > > > - Add basic RGB support on hid-asus, (Z13/Ally) tested in KDE/Z13
> > > > > - Fix ifdef else having an invalid signature (reported by kernel robot)
> > > > > - Restore input arguments to init and keyboard function so they can
> > > > > be re-used for RGB controls.
> > > > > - Remove Z13 delay (it did not work to fix the touchpad) and replace it
> > > > > with a HID_GROUP_GENERIC quirk to allow hid-multitouch to load. Squash
> > > > > keyboard rename into it.
> > > > > - Unregister brightness listener before removing work queue to avoid
> > > > > a race condition causing corruption
> > > > > - Remove spurious mutex unlock in asus_brt_event
> > > > > - Place mutex lock in kbd_led_set after LED_UNREGISTERING check to avoid
> > > > > relocking the mutex and causing a deadlock when unregistering leds
> > > > > - Add extra check during unregistering to avoid calling unregister when
> > > > > no led device is registered.
> > > > > - Temporarily HID_QUIRK_INPUT_PER_APP from the ROG endpoint as it causes
> > > > > the driver to create 4 RGB handlers per device. I also suspect some
> > > > > extra events sneak through (KDE had the @@@@@@).
> > > > >
> > > > > Antheas Kapenekakis (7):
> > > > > HID: asus: refactor init sequence per spec
> > > > > HID: asus: prevent binding to all HID devices on ROG
> > > > > platform/x86: asus-wmi: Add support for multiple kbd RGB handlers
> > > > > HID: asus: listen to the asus-wmi brightness device instead of
> > > > > creating one
> > > > > platform/x86: asus-wmi: remove unused keyboard backlight quirk
> > > > > platform/x86: asus-wmi: add keyboard brightness event handler
> > > > > HID: asus: add support for the asus-wmi brightness handler
> > > > >
> > > > > drivers/hid/hid-asus.c | 235 +++++++++++----------
> > > > > drivers/platform/x86/asus-wmi.c | 157 ++++++++++++--
> > > > > include/linux/platform_data/x86/asus-wmi.h | 69 +++---
> > > > > 3 files changed, 291 insertions(+), 170 deletions(-)
> > > > >
> > > > >
> > > > > base-commit: 3a8660878839faadb4f1a6dd72c3179c1df56787
> > > >
> > >
> >
> >