[Linux-kernel-mentees] Any other ways to debug GPIO interrupt controller (pinctrl-amd) for broken touchpads of a new laptop model?

[Andy Shevchenko]

On Tue, Nov 3, 2020 at 12:12 PM Hans de Goede <hdegoede at redhat.com> wrote:
> On 11/3/20 1:05 AM, Coiby Xu wrote:
> > On Tue, Oct 27, 2020 at 11:09:11AM +0100, Hans de Goede wrote:

...

> > [1] https://lore.kernel.org/patchwork/comment/1522675/
>
> This is a case where Andy is obviously right and you should just use the
> higher precision "unit = 15625" value (except probably that is wrong too,
> see below).
>
> We have had similar issues with the docs for getting the TSC frequency
> on some Intel chips, where the docs said 16.6 MHz for a certain register
> value, where what they meant was 100/6 MHz which really is significantly
> different. This was leading to a time drift of 5 minutes / day on non
> networked (so no NTP) Linux systems.
>
> I think this is what Andy was referring to when he wrote:
> "What the heck with HW companies! (Just an emotion based on the experience)"

Exactly!

...

> Actually all the values look somewhat suspect. The comment:
>
> >                 Debounce        Debounce        Timer   Max
> >                 TmrLarge        TmrOutUnit      Unit    Debounce
> >                                                         Time
> >                 0       0       61 usec (2 RtcClk)      976 usec
> >                 0       1       244 usec (8 RtcClk)     3.9 msec
> >                 1       0       15.6 msec (512 RtcClk)  250 msec
> >                 1       1       62.5 msec (2048 RtcClk) 1 sec
>
> Helpfully gives the values in RtcClks. A typical RTC clock crystal
> is 32 KHz which gives us 31.25 usec per tick, so I would expect the
> values to be:

I guess you are mistaken here. Usual frequency for RTC is 32.768kHz
[1], which gives more or less above values

30.51757
61.03515
244.14062
15625
62500

[1]: https://en.wikipedia.org/wiki/Real-time_clock
(just google: rtc clock frequency)

-- 
With Best Regards,
Andy Shevchenko