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From: Andy Shevchenko <andy.shevchenko@gmail.com>
To: Hans de Goede <hdegoede@redhat.com>
Cc: Coiby Xu <coiby.xu@gmail.com>,
	Linus Walleij <linus.walleij@linaro.org>,
	"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
	wang jun <availa@outlook.com>,
	Nehal Shah <Nehal-bakulchandra.Shah@amd.com>,
	Shyam Sundar S K <Shyam-sundar.S-k@amd.com>,
	linux-kernel-mentees@lists.linuxfoundation.org
Subject: Re: Any other ways to debug GPIO interrupt controller (pinctrl-amd) for broken touchpads of a new laptop model?
Date: Tue, 3 Nov 2020 12:49:09 +0200	[thread overview]
Message-ID: <CAHp75VdYhe4YEAzULMNkhihTQwHAP3fC2F6iD=datqzyzd=4fQ@mail.gmail.com> (raw)
In-Reply-To: <2f4706a1-502f-75f0-9596-cc25b4933b6c@redhat.com>

On Tue, Nov 3, 2020 at 12:12 PM Hans de Goede <hdegoede@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

  reply	other threads:[~2020-11-03 10:48 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-01 13:22 Any other ways to debug GPIO interrupt controller (pinctrl-amd) for broken touchpads of a new laptop model? Coiby Xu
2020-10-01 20:57 ` Linus Walleij
2020-10-02  9:40   ` Hans de Goede
2020-10-02 12:42     ` Coiby Xu
2020-10-02 13:36       ` Hans de Goede
2020-10-02 14:51         ` Coiby Xu
2020-10-02 19:44           ` Hans de Goede
2020-10-02 22:45             ` Coiby Xu
2020-10-03 13:22               ` Hans de Goede
2020-10-03 23:03                 ` Coiby Xu
2020-10-04  5:16                   ` Coiby Xu
2020-10-06  4:49                     ` Coiby Xu
2020-10-06  6:28                       ` Hans de Goede
2020-10-06  8:31                         ` Coiby Xu
2020-10-06  8:55                           ` Hans de Goede
2020-10-06  9:28                             ` Hans de Goede
2020-10-06  9:29                               ` Hans de Goede
2020-10-08 16:32                                 ` Coiby Xu
2020-10-14  4:24                                 ` Coiby Xu
2020-10-14 11:34                                   ` Coiby Xu
2020-10-14 11:46                                   ` Hans de Goede
2020-10-15  3:27                                     ` Coiby Xu
2020-10-15  4:06                                     ` Coiby Xu
2020-10-26 22:54                                     ` Coiby Xu
2020-10-27  9:52                                       ` Andy Shevchenko
2020-10-30  4:58                                         ` Coiby Xu
2020-10-27 10:09                                       ` Hans de Goede
2020-10-27 15:13                                         ` Andy Shevchenko
2020-10-27 16:00                                           ` Hans de Goede
2020-10-27 16:09                                             ` Andy Shevchenko
2020-10-29  8:04                                               ` Mika Westerberg
2020-10-30  4:54                                               ` Coiby Xu
2020-11-02 19:06                                                 ` Andy Shevchenko
2020-11-02 22:56                                                   ` Coiby Xu
2020-11-03  0:05                                         ` Coiby Xu
2020-11-03 10:12                                           ` Hans de Goede
2020-11-03 10:49                                             ` Andy Shevchenko [this message]
2020-11-03 11:00                                               ` Hans de Goede
2020-10-08 16:26                               ` Coiby Xu
2020-10-06  9:16                           ` Linus Walleij
2020-10-08 16:40                             ` Coiby Xu
2020-10-02 10:59   ` Coiby Xu

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