Thread (20 messages) 20 messages, 4 authors, 2025-06-25

Re: [PATCH 2/2] Revert "Input: soc_button_array - debounce the buttons"

From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Date: 2025-06-25 15:10:35
Also in: linux-acpi, linux-gpio, lkml

On Wed, Jun 25, 2025 at 03:02:18PM +0000, Limonciello, Mario wrote:
On 6/25/25 9:41 AM, Mario Limonciello wrote:
quoted
On 6/25/25 9:31 AM, Hans de Goede wrote:
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On 25-Jun-25 4:09 PM, Mario Limonciello wrote:
quoted
On 6/25/25 4:09 AM, Hans de Goede wrote:
quoted
On 24-Jun-25 10:22 PM, Mario Limonciello wrote:
...
quoted
quoted
Ok, so specifically the gpiod_set_debounce() call with 50 ms
done by gpio_keys.c is the problem I guess?
Yep.
quoted
So amd_gpio_set_debounce() does accept the 50 ms debounce
passed to it by gpio_keys.c as a valid value and then setting
that breaks the wake from suspend?
That's right.
quoted
quoted
quoted
Also comparing the GPIO register in Windows (where things work) 
Windows never programs a debounce.
So maybe the windows ACPI0011 driver always uses a software-
debounce for the buttons? Windows not debouncing the mechanical
switches at all seems unlikely.

I think the best way to fix this might be to add a no-hw-debounce
flag to the data passed from soc_button_array.c to gpio_keys.c
and have gpio_keys.c not call gpiod_set_debounce()  when the
no-hw-debounce flag is set.

I've checked and both on Bay Trail and Cherry Trail devices
where soc_button_array is used a lot hw-debouncing is already
unused. pinctrl-baytrail.c does not accept 50 ms as a valid
value and pinctrl-cherryview.c does not support hw debounce
at all.
That sounds a like a generally good direction to me.
Thinking a bit more of this, perhaps the HW debounce support flag should be
per-GPIO-descriptor thingy. In such cases we don't need to distinguish the
platforms, the GPIO ACPI lib may simply set that flag based on 0 read from
the ACPI tables. It will also give a clue to any driver that uses GPIOs
(not only gpio-keys).

-- 
With Best Regards,
Andy Shevchenko

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