linux-kernel - Re: [PATCH v4] pinctrl: amd: remove debounce filter setting in IRQ type setting

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Date:   Wed, 25 Nov 2020 15:24:20 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Coiby Xu <coiby.xu@...il.com>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Baq Domalaq <domalak@...il.com>,
        Pedro Ribeiro <pedrib@...il.com>,
        Hans de Goede <hdegoede@...hat.com>,
        Benjamin Tissoires <benjamin.tissoires@...hat.com>,
        Stable <stable@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4] pinctrl: amd: remove debounce filter setting in IRQ
 type setting

On Wed, Nov 25, 2020 at 3:03 PM Coiby Xu <coiby.xu@...il.com> wrote:
>
> Debounce filter setting should be independent from IRQ type setting
> because according to the ACPI specs, there are separate arguments for
> specifying debounce timeout and IRQ type in GpioIo() and GpioInt().
>
> Together with commit 06abe8291bc31839950f7d0362d9979edc88a666
> ("pinctrl: amd: fix incorrect way to disable debounce filter") and
> Andy's patch "gpiolib: acpi: Take into account debounce settings" [1],
> this will fix broken touchpads for laptops whose BIOS set the
> debounce timeout to a relatively large value. For example, the BIOS
> of Lenovo AMD gaming laptops including Legion-5 15ARH05 (R7000),
> Legion-5P (R7000P) and IdeaPad Gaming 3 15ARH05, set the debounce
> timeout to 124.8ms. This led to the kernel receiving only ~7 HID
> reports per second from the Synaptics touchpad
> (MSFT0001:00 06CB:7F28).
>
> Existing touchpads like [2][3] are not troubled by this bug because
> the debounce timeout has been set to 0 by the BIOS before enabling
> the debounce filter in setting IRQ type.
>
> [1] https://lore.kernel.org/linux-gpio/20201111222008.39993-11-andriy.shevchenko@linux.intel.com/

JFYI: this is nowadays
8dcb7a15a585 ("gpiolib: acpi: Take into account debounce settings")

(No need to recend, just an information that can be applied maybe by Linus)

> [2] https://github.com/Syniurge/i2c-amd-mp2/issues/11#issuecomment-721331582
> [3] https://forum.manjaro.org/t/random-short-touchpad-freezes/30832/28

-- 
With Best Regards,
Andy Shevchenko