Re: platform/x86: asus-wmi: SW_TABLET_MODE is always 1 on some devices

[Hans de Goede]

Hi,

On 9/1/20 11:55 PM, Samuel Čavoj wrote:
> Hello!
>
> A bug was introduced with the following commit[1]:
>
>      b0dbd97de: platform/x86: asus-wmi: Add support for SW_TABLET_MODE
>
> The SW_TABLET_MODE switch seems to be always 1 on some devices,
> including my UX360CA and a UX390UAK[2].
>
> This can be seen in the output of evtest:
>
>      # evtest /dev/input/by-path/platform-asus-nb-wmi-event
>      Input driver version is 1.0.1
>      Input device ID: bus 0x19 vendor 0x0 product 0x0 version 0x0
>      Input device name: "Asus WMI hotkeys"
>      Supported events:
>        (...)
>        Event type 5 (EV_SW)
>          Event code 1 (SW_TABLET_MODE) state 1
>
> And directly results in libinput disabling the trackpad and keyboard via
> its tablet-mode mechanism, rendering X.org and Wayland unusable (not even
> switching to VT works without sysrq+r):
>
>      # libinput debug-events
>      (...)
>      -event8   DEVICE_ADDED     Asus WMI hotkeys     seat0 default group10 cap:kS
>       event8   SWITCH_TOGGLE    +0.000s	switch tablet-mode state 1
>      (...)
>
> I have been using the following workaround to get my input working
> again:
>
>      # cat /usr/share/libinput/50-system-asus.quirks
>      (...)
>      [Asus WMI hotkeys]
>      MatchName=*Asus WMI hotkeys*
>      ModelTabletModeSwitchUnreliable=1
>
> Another option would be to rmmod asus_nb_wmi and blacklist it for now.
>
> I am not sure what the solution would be as I am not acquainted with the
> WMI module. However, I can provide some information about my hardware:
>
> The UX360CA fully disables the keyboard in hardware(firmware?) when the
> lid is flipped beyond 180 degrees (tablet mode). The trackpad is not
> disabled. A KEY_PROG2 event is generated by the same "Asus WMI hotkeys"
> input device at this moment, it however does not carry the actual state
> -- a 1 is sent and a 0 follows immediately[3]. The same KEY_PROG2
> sequence is generated when the lid is returned back to laptop position.
> The SW_TABLET_MODE switch does not change state at all during this.
> Thank you.

Thank you for your detailed bug report.

I have only tested the new TABLET_MODE support on Bay Trail and
Cherry Trail based devices. So one possible solution would be to
limit the support based on cpu-id.

But I would rather try to figure out a better way. Can you
create an acpidump, by as root running:

acpidump -o acpidump.asus-UX360CA

And then send me a direct (so without including the list)
email with the generated acpidump.asus-UX360CA file attached please?

Also, if necessary are you capable of building your own
kernel with a (test)patch applied ?

Regards,

Hans