Re: Elantech touchpad not working on mainline kernels

On Thu, 2021-07-22 at 09:55 +0200, Benjamin Tissoires wrote:

On Wed, Jul 21, 2021 at 10:42 PM Dmitry Torokhov
[off-list ref] wrote:

quoted

On Wed, Jul 21, 2021 at 12:53 PM Hans Schultz <
hans.schultz@webspeed.dk> wrote:

quoted

On Wed, 2021-07-21 at 21:31 +0200, Hans Schultz wrote:

quoted

Hi Dmitry,

On Wed, 2021-07-21 at 12:14 -0700, Dmitry Torokhov wrote:

quoted

On Wed, Jul 21, 2021 at 11:09 AM Hans Schultz <
hans.schultz@webspeed.dk> wrote:

quoted

On Wed, 2021-07-21 at 10:48 -0700, Dmitry Torokhov wrote:

quoted

Hi Hans,

On Sun, May 30, 2021 at 2:12 AM Hans Schultz <
hans.schultz@webspeed.dk> wrote:

quoted

Hello,
I have a problem getting my Elantech touchpad to work
with
the
mainline
kernels, and I need some assistance with the code to
resolve
the
problem.
The kernels that have tried are 5.9.11 and 5.11.11.

With boot parameters i8042.notimeout i8042.nomux, the
touchpad is
detected but does not work. There is absolutely no
response
from
it
with any hid modules loaded.

It is reported and seen working on a Lubuntu distro
(bionic
kernel)
when inserting the i2c_hid module. The insertion of the
i2c_hid
module
pulls in the hid_multitouch module when it works, no
boot
parameters
necessary.
In the case where it does not work, insering the
i2c_hid
module
does
not pull in the hid_multitouch module.

I have the bionic kernel code, but I have not as of yet
been
able
to
detect what makes it work in contrast to the kernel.org
kernels.

This I think should lead to a kernel patch.

There is not much to go on with. What is the hardware,
your
kernel
.config, dmesg from unsuccessful boot? If you have logs
from
the
working kernel that would help too.

Thanks.

The best info I have on the hardware is from Xorg log with
the
working
Lubuntu kernel:
[ 130.980] (II) Loading
/usr/lib/xorg/modules/input/synaptics_drv.so
[ 130.982] (II) Module synaptics: vendor="X.Org Foundation"
[ 130.982] (II) Using input driver 'synaptics' for '0X45
0X4C
0X41
0:00
04F3:308C Touchpad'

I might be able to get the kernel messages when inserting
the
working
module, but I think it will not tell much more.

OK, if you say so. Then the only suggestion I have is to
verify
that
your kernel config enables all necessary options for your
hardware.
I'd double check if you have Designware I2C controller
enabled,
ACPI
LPSS, etc.

quoted

To me it is clearly a code issue as the working kernel
pulls in
hid_multitouch when inserting i2c_hid, while the non-
working does
not.

All kernels I have tried up to now from kernel.org do not
work.
The
latest being 5.13.4.

Thanks.

I have a thread with all the dmesg info for both the working
and non-
working cases here :
https://gitlab.freedesktop.org/libinput/libinput/-/issues/544

Benjamin has also asked for the acpidump info, which is there.
(funny
as the responses to my problem come at the same time after a
long
time.
:-) )

I will check my .config...

Thanks,
Hans

Here are my I2C kernel settings. I only added what I could see as
with
Intel hw, so no Designware!

However if you consult the dmesg from the working kernel you will
observe:

[   79.964148] input: 0X45 0X4C 0X41 0:00 04F3:308C Mouse as
/devices/pci0000:00/0000:00:15.3/i2c_designware.1/i2c-8/i2c-0X45
0X4C
0X41 0:00/0018:04F3:308C.0002/input/input24
[   79.964222] input: 0X45 0X4C 0X41 0:00 04F3:308C Touchpad as
/devices/pci0000:00/0000:00:15.3/i2c_designware.1/i2c-8/i2c-0X45
0X4C
0X41 0:00/0018:04F3:308C.0002/input/input26

so it clearly uses designware-compatible IP block even though it is
an
Intel system.

FWIW, I think Intel platform *always* rely on designware for the I2C
adapter implementation. So if you haven't enabled that driver there
is
no chance for you to have a working touchpad.

Cheers,
Benjamin

quoted

Can you try grabbing config from the working kernel and use it if
you
want to compile your own? There are a lot of hardware dependencies
in
modern systems that may not be immediately obvious.

Thanks.

--
Dmitry

I have now tried taking the kernel config from the working example and
building a 5.13.4 kernel based on that, but it still does not work.

My original approach was assuming that the Lubuntu kernel was module
based, which they normally are to be flexible, and checking module for
module what I had of modules in my kernel build and the module list
from the Lubuntu kernel.

The designware part in the Lubuntu kernel it shows was not included as
a module but was in the kernel bin. Adding the designware parts to my
kernel did not resolve the issue either.

Still inserting i2c_hid does not pull in hid_multitouch.

Is there code differences that Ubuntu have made to their kernel that
can explain this? I have been looking through the code and there is
definitely differences, f.ex. in the quirks department.