Re: [PATCH 2/2] Revert "Input: soc_button_array - debounce the buttons"
From: Hans de Goede <hansg@kernel.org>
Date: 2025-06-25 09:09:29
Also in:
linux-acpi, linux-gpio, lkml
Hi Mario, On 24-Jun-25 10:22 PM, Mario Limonciello wrote:
From: Mario Limonciello <mario.limonciello@amd.com>
commit 5c4fa2a6da7fb ("Input: soc_button_array - debounce the buttons")
hardcoded all soc-button-array devices to use a 50ms debounce timeout
but this doesn't work on all hardware. The hardware I have on hand
actually prescribes in the ASL that the timeout should be 0:
GpioInt (Edge, ActiveBoth, Exclusive, PullUp, 0x0000,
"\\_SB.GPIO", 0x00, ResourceConsumer, ,)
{ // Pin list
0x0000
}
Let the GPIO core program the debounce instead of hardcoding it into a
driver.
This reverts commit 5c4fa2a6da7fbc76290d1cb54a7e35633517a522.This is going to cause problems I'm afraid I just checked and based on randomly checking a few DSDTs of the tablets this driver is used on, it seems the DSDT always specifies a debounce timeout of 0 like your example above. And on many many devices using the soc_button_array driver debouncing is actually necessary. May I ask what problem you are seeing with the 50ms debounce timeout / what problem you are exactly trying to fix here ? drivers/input/keyboard/gpio_keys.c first will call gpiod_set_debounce() it self with the 50 ms provided by soc_button_array and if that does not work it will fall back to software debouncing. So I don't see how the 50 ms debounce can cause problems, other then maybe making really really (impossible?) fast double-clicks register as a single click . These buttons (e.g. volume up/down) are almost always simply mechanical switches and these definitely will need debouncing, the 0 value from the DSDT is plainly just wrong. There is no such thing as a not bouncing mechanical switch. Regards, Hans
quoted hunk ↗ jump to hunk
Cc: Hans de Goede <hansg@kernel.org> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com> --- drivers/input/misc/soc_button_array.c | 2 -- 1 file changed, 2 deletions(-)diff --git a/drivers/input/misc/soc_button_array.c b/drivers/input/misc/soc_button_array.c index b8cad415c62ca..99490df42b6f2 100644 --- a/drivers/input/misc/soc_button_array.c +++ b/drivers/input/misc/soc_button_array.c@@ -219,8 +219,6 @@ soc_button_device_create(struct platform_device *pdev, gpio_keys[n_buttons].active_low = info->active_low; gpio_keys[n_buttons].desc = info->name; gpio_keys[n_buttons].wakeup = info->wakeup; - /* These devices often use cheap buttons, use 50 ms debounce */ - gpio_keys[n_buttons].debounce_interval = 50; n_buttons++; }