Re: [PATCH] ELAN touchpad i2c_hid bugs fix

[Hans de Goede <hdegoede@redhat.com>]

Hi Dmitry,

On 25-03-19 17:02, Dmitry Torokhov wrote:
> Hi Vladislav,
> 
> On Mon, Mar 25, 2019 at 5:57 AM Vladislav Dalechyn
> <vlad.dalechin@gmail.com> wrote:
>>
>> From: Vladislav Dalechyn <hotwater438@tutanota.com>
>>
>> Description: The ELAN1200:04F3:303E touchpad exposes several issues, all
>> caused by an error setting the correct IRQ_TRIGGER flag:
>> - i2c_hid incoplete error flood in journalctl;
>> - Five finger tap kill's module so you have to restart it;
>> - Two finger scoll is working incorrect and sometimes even when you
>> raised one of two finger still thinks that you are scrolling.
>>
>> Fix all of these with a new quirk that corrects the trigger flag
>> announced by the ACPI tables. (edge-falling).
> 
> I do not believe this is right solution. The driver makes liberal use
> of disable_irq() and enable_irq() which may lead to lost edges and
> touchpad stopping working altogether.
> 
> Usually the "extra" report is caused by GPIO controller clearing
> interrupt condition at the wrong time (too early), or in unsafe or
> racy fashion. You need to look there instead of adding quirk to
> i2c-hid.

The falling-edge solution was proposed by Elan themselves.

Also if you look at: https://bugzilla.redhat.com/show_bug.cgi?id=1543769

And esp. the "cat /proc/interrupts" output there, then you will see
that the interrupt seems to be stuck at low level, which according
to the ACPI tables is its active level.

As for this being a GPIO chip driver problem, this is using standard
Intel pinctrl stuff, which is not showing this same issue with many
other i2c-hid touchpads.

Regards,

Hans