Re: [PATCH] platform/x86: intel_cht_int33fe: Work around BIOS bug on some devices

[Hans de Goede]

Hi,

On 09/01/2017 11:19 AM, Mika Westerberg wrote:
> On Thu, Aug 31, 2017 at 07:04:46PM +0300, Andy Shevchenko wrote:
> > On Mon, Aug 14, 2017 at 11:52 PM, Hans de Goede <hdegoede@xxxxxxxxxx> wrote:
> > > On 14-08-17 22:45, Andy Shevchenko wrote:
> > > > On Mon, Aug 14, 2017 at 11:14 PM, Hans de Goede <hdegoede@xxxxxxxxxx>
> > > > wrote:
> >
> > > > > +int cht_int33fe_check_for_max17047(struct device *dev, void *data)
> > > > > +{
> > > > > +       const char *name = dev_name(dev);
> > > > > +       struct i2c_client **max17047 = data;
> > > > > +
> > > > > +       if (name && strcmp(name, "i2c-MAX17047:00") == 0) {
> > > >
> > > >
> > > > Can we stop using bad practice of comparing against _instance_?
> > > > If device is suppose to be single in the system, wouldn't _HID be enough?
> >
> > > Yes _HID would be enough, but that takes some extra code with little
> > > gain IMHO, we are effectively checking the HID here as that is where
> > > the device-name comes from.
> > >
> > > Anyways if you strongly prefer a HID check I can do a v2 doing that
> > > either way let me know.
> >
> > Currently we have the following modules where ACPI instance is used in:
> >
> > drivers/acpi/acpi_lpss.c
> > drivers/input/touchscreen/goodix.c
> > drivers/platform/x86/silead_dmi.c
> > drivers/power/supply/axp288_charger.c
> >
> > and plenty under sound/soc/intel.
> >
> > I do not care right now about sound/soc/intel stuff, while everywhere
> > else would be better to avoid this.
> >
> > Mika, Rafael, what're yours opinions regarding to use ACPI instances
> > in the drivers?
>
> Since the instance name is generated by the ACPI core and in theory
> could change, I agree this is pretty fragile. Using _HID/_UID should be
> the preferred way. However, it is not always possible so we end up doing
> hacks like this.

Given that on the device in question where we need this workaround there
is only ever 1 max17047, including the instance number in the check really
is a non-problem, but if there is a strong preference for me to change
the check over to a _HID check then I can do a v2 doing so.

Regards,

Hans