Dell laptop touchpad disabling?

Dell laptop touchpad disabling?

[Randy Dunlap]

Hi all,

I have a Dell Inspiron 15 5510 laptop. Of course, it has a touchpad
(which I think of as a nuisance pad).
I would like to be able to disable the touchpad easily.

Are there any best practices or suggestions for how to do this?
(I am using xfce4 as the desktop environment if that matters.)


Sometimes the touchpad is discovered as a PS/2 Generic Mouse on
the i8042 AUX port, and sometimes it is discovered as this
touchpad: "DELL0B24:00 04F3:3147 Touchpad" on some I2C device:
"i2c-DELL0B24:00". (The different discoveries might have something
to do with my kernel configuration/builds, but I don't know that
for sure.)

I have some very hackish scripts that I can run to toggle the
'inhibited' flag in sysfs (/sys/class/input/ for the I2C device or
or /sys/devices/platform/i8042/ for the i8042 AUX port device),
but that requires root (sudo), so that does not qualify as "easily"
IMO.

E.g.,
$ sudo toggle-aux-mouse
or
$ sudo toggle-i2c-touchpad

depending on which configuration the device is in.


Thanks for any advice etc.
-- 
~Randy

Re: Dell laptop touchpad disabling?

[Hans de Goede]

Hi Randy,

On 3/18/22 01:32, Randy Dunlap wrote:
> Hi all,
> 
> I have a Dell Inspiron 15 5510 laptop. Of course, it has a touchpad
> (which I think of as a nuisance pad).
> I would like to be able to disable the touchpad easily.
> 
> Are there any best practices or suggestions for how to do this?
> (I am using xfce4 as the desktop environment if that matters.)
> 
> 
> Sometimes the touchpad is discovered as a PS/2 Generic Mouse on
> the i8042 AUX port, and sometimes it is discovered as this
> touchpad: "DELL0B24:00 04F3:3147 Touchpad" on some I2C device:
> "i2c-DELL0B24:00". (The different discoveries might have something
> to do with my kernel configuration/builds, but I don't know that
> for sure.)
> 
> I have some very hackish scripts that I can run to toggle the
> 'inhibited' flag in sysfs (/sys/class/input/ for the I2C device or
> or /sys/devices/platform/i8042/ for the i8042 AUX port device),
> but that requires root (sudo), so that does not qualify as "easily"
> IMO.
> 
> E.g.,
> $ sudo toggle-aux-mouse
> or
> $ sudo toggle-i2c-touchpad
> 
> depending on which configuration the device is in.

The touchpad is supposed to be always recognized as, well a touchpad,
so you want it to show up as "DELL0B24:00 04F3:3147 Touchpad", as
you said this likely depends on your kernel config.

And then usually the desktop environment will give you an option
to disable it. At least GNOME offers a clear on/off toggle see:

Re: Dell laptop touchpad disabling?

[Hans de Goede]

<attempt 2, fat-fingered send>

Hi Randy,

On 3/18/22 01:32, Randy Dunlap wrote:
> Hi all,
> 
> I have a Dell Inspiron 15 5510 laptop. Of course, it has a touchpad
> (which I think of as a nuisance pad).
> I would like to be able to disable the touchpad easily.
> 
> Are there any best practices or suggestions for how to do this?
> (I am using xfce4 as the desktop environment if that matters.)
> 
> 
> Sometimes the touchpad is discovered as a PS/2 Generic Mouse on
> the i8042 AUX port, and sometimes it is discovered as this
> touchpad: "DELL0B24:00 04F3:3147 Touchpad" on some I2C device:
> "i2c-DELL0B24:00". (The different discoveries might have something
> to do with my kernel configuration/builds, but I don't know that
> for sure.)
> 
> I have some very hackish scripts that I can run to toggle the
> 'inhibited' flag in sysfs (/sys/class/input/ for the I2C device or
> or /sys/devices/platform/i8042/ for the i8042 AUX port device),
> but that requires root (sudo), so that does not qualify as "easily"
> IMO.
> 
> E.g.,
> $ sudo toggle-aux-mouse
> or
> $ sudo toggle-i2c-touchpad
> 
> depending on which configuration the device is in.

The touchpad is supposed to be always recognized as, well a touchpad,
so you want it to show up as "DELL0B24:00 04F3:3147 Touchpad", as
you said this likely depends on your kernel config.

And then usually the desktop environment will give you an option
to disable it. At least GNOME offers a clear on/off toggle see e.g. :

https://blog.separateconcerns.com/img/gnome-touchpad-settings.jpg

Or you could use xinput properties to set the matching xinput
device, to disabled which you can do by device-name:

https://linuxhint.com/change_mouse_touchpad_settings_xinput_linux/

And then change the "Device Enabled" property.

Regardless of the method, the kernel's responsibility here is
to make sure the touchpad gets seen as a touchpad and after that
"disabling" it is a userspace problem.

Regards,

Hans

Re: Dell laptop touchpad disabling?

[Randy Dunlap]

Hi Hans,

On 3/18/22 01:54, Hans de Goede wrote:
> <attempt 2, fat-fingered send>
> 
> Hi Randy,
> 
> On 3/18/22 01:32, Randy Dunlap wrote:
>> Hi all,
>>
>> I have a Dell Inspiron 15 5510 laptop. Of course, it has a touchpad
>> (which I think of as a nuisance pad).
>> I would like to be able to disable the touchpad easily.
>>
>> Are there any best practices or suggestions for how to do this?
>> (I am using xfce4 as the desktop environment if that matters.)
>>
>>
>> Sometimes the touchpad is discovered as a PS/2 Generic Mouse on
>> the i8042 AUX port, and sometimes it is discovered as this
>> touchpad: "DELL0B24:00 04F3:3147 Touchpad" on some I2C device:
>> "i2c-DELL0B24:00". (The different discoveries might have something
>> to do with my kernel configuration/builds, but I don't know that
>> for sure.)
>>
>> I have some very hackish scripts that I can run to toggle the
>> 'inhibited' flag in sysfs (/sys/class/input/ for the I2C device or
>> or /sys/devices/platform/i8042/ for the i8042 AUX port device),
>> but that requires root (sudo), so that does not qualify as "easily"
>> IMO.
>>
>> E.g.,
>> $ sudo toggle-aux-mouse
>> or
>> $ sudo toggle-i2c-touchpad
>>
>> depending on which configuration the device is in.
> 
> The touchpad is supposed to be always recognized as, well a touchpad,
> so you want it to show up as "DELL0B24:00 04F3:3147 Touchpad", as
> you said this likely depends on your kernel config.
> 
> And then usually the desktop environment will give you an option
> to disable it. At least GNOME offers a clear on/off toggle see e.g. :
> 
> https://blog.separateconcerns.com/img/gnome-touchpad-settings.jpg

OK, I finally found that. and it works.

> Or you could use xinput properties to set the matching xinput
> device, to disabled which you can do by device-name:
> 
> https://linuxhint.com/change_mouse_touchpad_settings_xinput_linux/
> 
> And then change the "Device Enabled" property.

and that also works.

> Regardless of the method, the kernel's responsibility here is
> to make sure the touchpad gets seen as a touchpad and after that
> "disabling" it is a userspace problem.

Sure, I get it.

Thanks for your help.

Re: [External] Re: Dell laptop touchpad disabling?

[Mark Pearson]

Apologies if this is thread hijacking...but I've got a similarish
problem on Lenovo laptops that we have on the todo list to investigate
so wanted to jump in with a somewhat related question...

On 3/18/22 04:54, Hans de Goede wrote:
> 
> Regardless of the method, the kernel's responsibility here is
> to make sure the touchpad gets seen as a touchpad and after that
> "disabling" it is a userspace problem.
> 

The issue on our platforms is that if you disable the touchpad in the
BIOS it doesn't actually disable the touchpad. It sets a flag in the EC
registers to let the OS know the touchpad is not supposed to be enabled
(I only just found out this is how it is supposed to work).

I'm not 100% sure the reasons for this - I think it's to do with keeping
the trackpoint usable (maybe).

So just curious on the comment above - is there a standard way to let
user space know to ignore the touchpad or disable it by default?

I'm obviously being lazy here as I've been meaning to go and read code
but I was flicking thru the mailing list and this caught my eye....and
if there's a shortcut to the answer that would be awesome.

I've no idea if this is a Lenovo specific issue or more generic - but
this thread made me wonder if it's actually a common/standard problem?

Mark

Re: [External] Re: Dell laptop touchpad disabling?

[Hans de Goede]

Hi Mark,

On 3/21/22 23:18, Mark Pearson wrote:
> 
> Apologies if this is thread hijacking...but I've got a similarish
> problem on Lenovo laptops that we have on the todo list to investigate
> so wanted to jump in with a somewhat related question...

No problem.

> On 3/18/22 04:54, Hans de Goede wrote:
>>
>> Regardless of the method, the kernel's responsibility here is
>> to make sure the touchpad gets seen as a touchpad and after that
>> "disabling" it is a userspace problem.
>>
> 
> The issue on our platforms is that if you disable the touchpad in the
> BIOS it doesn't actually disable the touchpad. It sets a flag in the EC
> registers to let the OS know the touchpad is not supposed to be enabled
> (I only just found out this is how it is supposed to work).

Interesting.

> I'm not 100% sure the reasons for this - I think it's to do with keeping
> the trackpoint usable (maybe).

Yes that makes sense the trackpoint often sends its data to the touchpad
which then muxes the trackpoint data into its own datastream as special
trackpoint packets. So disabling the touchpad at the hw level would also
disable the trackpoint in these kinda setups.

> So just curious on the comment above - is there a standard way to let
> user space know to ignore the touchpad or disable it by default?

Not yet, but we could define one. Or we could even try to see if
a patch to drop all non trackpoint data inside the kernel when the
flag is set would be accepted.

Someone needs to write the code for this though and if we want to let
userspace know also define a userspace API. I think the all kernel
solution might be the easiest to implement, but I'm not sure if this
will be accepted by the input subsystem maintainer.

> I'm obviously being lazy here as I've been meaning to go and read code
> but I was flicking thru the mailing list and this caught my eye....and
> if there's a shortcut to the answer that would be awesome.
> 
> I've no idea if this is a Lenovo specific issue or more generic - but
> this thread made me wonder if it's actually a common/standard problem?

This is the first time I have heard about this.

Regards,

Hans

Re: [External] Re: Dell laptop touchpad disabling?

[Pali Rohár]

Hello!

On Monday 11 April 2022 15:48:48 Hans de Goede wrote:
> Hi Mark,
> 
> On 3/21/22 23:18, Mark Pearson wrote:
> > 
> > Apologies if this is thread hijacking...but I've got a similarish
> > problem on Lenovo laptops that we have on the todo list to investigate
> > so wanted to jump in with a somewhat related question...
> 
> No problem.
> 
> > On 3/18/22 04:54, Hans de Goede wrote:
> >>
> >> Regardless of the method, the kernel's responsibility here is
> >> to make sure the touchpad gets seen as a touchpad and after that
> >> "disabling" it is a userspace problem.
> >>
> > 
> > The issue on our platforms is that if you disable the touchpad in the
> > BIOS it doesn't actually disable the touchpad. It sets a flag in the EC
> > registers to let the OS know the touchpad is not supposed to be enabled
> > (I only just found out this is how it is supposed to work).
> 
> Interesting.
> 
> > I'm not 100% sure the reasons for this - I think it's to do with keeping
> > the trackpoint usable (maybe).
> 
> Yes that makes sense the trackpoint often sends its data to the touchpad
> which then muxes the trackpoint data into its own datastream as special
> trackpoint packets. So disabling the touchpad at the hw level would also
> disable the trackpoint in these kinda setups.

That is truth. And some kernel drivers are smart and try to de-mux these
packets and reports trackstick events via different input device as
touchpad input device. So via xinput it is possible to disable e.g.
touchpad while keeping trackstick working. This disable method is of
course Xserver specific and just instruct Xserver to ignore events on
one input device.

> > So just curious on the comment above - is there a standard way to let
> > user space know to ignore the touchpad or disable it by default?
> 
> Not yet, but we could define one. Or we could even try to see if
> a patch to drop all non trackpoint data inside the kernel when the
> flag is set would be accepted.
> 
> Someone needs to write the code for this though and if we want to let
> userspace know also define a userspace API. I think the all kernel
> solution might be the easiest to implement, but I'm not sure if this
> will be accepted by the input subsystem maintainer.

There is really no standard way...

> > I'm obviously being lazy here as I've been meaning to go and read code
> > but I was flicking thru the mailing list and this caught my eye....and
> > if there's a shortcut to the answer that would be awesome.
> > 
> > I've no idea if this is a Lenovo specific issue or more generic - but
> > this thread made me wonder if it's actually a common/standard problem?
> 
> This is the first time I have heard about this.
> 
> Regards,
> 
> Hans
> 

... and this not first time I read about this request. In past there was
request for Nokia N900 touchscreen driver and its userspace to disable
receiving events on opened touchscreen input device. External tool
monitored ambient light sensor and determined when phone was in pocket
and when not. And it needed to instruct kernel to not send touchscreen
events when phone was in pocket. IIRC at that time kernel for Nokia N900
had custom patch with custom API for enabling/disabling touchscreen.

This requirement is not exactly same as yours, but have common thing:
ability to enable / disable input device and report if device is
disabled or not.