Re: [PATCH] gpiolib: acpi: support override broken GPIO number in ACPI table

Shawn Guo
2021-02-27T03:47:30Z

On Fri, Feb 26, 2021 at 12:57:37PM +0200, Andy Shevchenko wrote:
> On Fri, Feb 26, 2021 at 11:39 AM Shawn Guo <shawn.guo@linaro.org> wrote:
> >
> > On Fri, Feb 26, 2021 at 11:12:07AM +0200, Andy Shevchenko wrote:
> > > On Fri, Feb 26, 2021 at 5:42 AM Shawn Guo <shawn.guo@linaro.org> wrote:
> > > >
> > > > Running kernel with ACPI on Lenovo Flex 5G laptop, touchpad is just
> > > > not working. That's because the GpioInt number of TSC2 node in ACPI
> > > > table is simply wrong, and the number even exceeds the maximum GPIO
> > > > lines. As the touchpad works fine with Windows on the same machine,
> > > > presumably this is something Windows-ism. Although it's obviously
> > > > a specification violation, believe of that Microsoft will fix this in
> > > > the near future is not really realistic.
> > > >
> > > > It adds the support of overriding broken GPIO number in ACPI table
> > > > on particular machines, which are matched using DMI info. Such
> > > > mechanism for fixing up broken firmware and ACPI table is not uncommon
> > > > in kernel. And hopefully it can be useful for other machines that get
> > > > broken GPIO number coded in ACPI table.
> > >
> > > Thanks for the report and patch.
> > >
> > > First of all, have you reported the issue to Lenovo? At least they
> > > will know that they did wrong.
> >
> > Yes, we are reporting this to Lenovo, but to be honest, we are not sure
> > how much they will care about it, as they are shipping the laptop with
> > Windows only.
> >
> > > Second, is it possible to have somewhere output of `acpidump -o
> > > flex5g.dat` (the flex5g.dat file)?
> >
> > https://raw.githubusercontent.com/aarch64-laptops/build/master/misc/lenovo-flex-5g/dsdt.dsl
> >
> > > And as Mika said once to one of mine patches "since you know the
> > > number ahead there is no need to pollute GPIO ACPI library core with
> > > this quirk". But in any case I would like to see the ACPI tables
> > > first.
> >
> > Oh, so you had something similar already? Could you point me to the
> > patch and discussion?
>
> Similar, but might be not the same:
> - patches in the upstream [1] (v3 applied), discussion [2]
> - new version with some additional fixes [3]

Thanks for all the pointers. It looks to me that it's the same problem
- the GPIO number in ACPI table is broken and needs an override from
kernel. So I think what we need is a generic solution to a problem
not uncommon. Rather than asking all different drivers to resolve the
same problem all over the kernel, I believe GPIO ACPI library is just
the right place.

Looking at your platform and problem, I realise that to be a generic
solution, my patch needs an additional device identification matching,
as one GPIO number that is broken for one device could be correct for
another. I will improve it, so that your problem can be resolved by
simply adding a new entry to acpi_gpio_pin_override_table[].

Shawn