From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 84C8E29E0E5; Wed, 25 Jun 2025 19:23:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750879437; cv=none; b=Ok59dVyc/k7yd+p8z7A++2X0E9Um/9cV7olVBmiiAk5BeGrTk6snYKm+YGo61nMajWAzAHrYiQEeineqPtmIqkNnVsiQvd7cFye1xfmPIzW44vpqAUuJpPLutIcI/LiiWcwDXZo+dLrZ3reWkwThnGm6uvqse0QKT1MRiTJQ7dk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750879437; c=relaxed/simple; bh=ImWZziYEqzoYqM1yZi/nIZNRa9eNS/1uwbab8RfLrBA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=eHni2NA/VaZIZu/71YqOR6s8LhV8rHieiqAeyiS4oeAzVV1eOPkLR6OJjEFaWzdFoDTpDPMvX/DJ/ocQDf2wzPS9JasTlxfd6ZU96Pfhcv11djmCcABYbZ0+cP7Dh6Jdf6NnC/UbtOeTys5YE3n0lyd2+MEMmT3SO5e5NpLeNP4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=mjjiscSN; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="mjjiscSN" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9AB69C4CEEA; Wed, 25 Jun 2025 19:23:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1750879437; bh=ImWZziYEqzoYqM1yZi/nIZNRa9eNS/1uwbab8RfLrBA=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=mjjiscSNO4mtefis8fS3NE/WxvY8cBBoU0CD9M/c6doMx7RS1dQsgIvr8X2QzWcrX Zsn9E91o9bBVQt2Rn00X/pBf5g2Zk3FsXdHw3+paa9ZX3no7oLZh3qabo7Xjdnjzpy kZZtVRKTCvYScuQq/zNuMaPzjaoLbs9u4YXedByfYUnbawy8aneiyAU4HktLi4lMUs Hd/8RYOpIYTEtwHm4pmwbKPrqMUDKyh3MjMzLMRBWcGWHTW4KmtYiri3nxl118xdhD Q4VB+bXpL61VuV9W2lwduXREL+2PZGaNAKu6wAX6TVrEjr3OClovjbhxykk3OUtcD2 OVThD/waphsDA== Message-ID: <57e9b1d5-faf1-4c7a-87fc-047e0dc102f9@kernel.org> Date: Wed, 25 Jun 2025 14:23:55 -0500 Precedence: bulk X-Mailing-List: linux-acpi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 3/3] Input: soc_button_array: Only debounce cherryview and baytrail systems To: Hans de Goede , Mika Westerberg , Andy Shevchenko , Linus Walleij , Bartosz Golaszewski , Dmitry Torokhov Cc: "open list:GPIO ACPI SUPPORT" , "open list:GPIO ACPI SUPPORT" , open list , "open list:INPUT (KEYBOARD, MOUSE, JOYSTICK, TOUCHSCREEN)..." , Mario Limonciello References: <20250625181342.3175969-1-superm1@kernel.org> <20250625181342.3175969-4-superm1@kernel.org> Content-Language: en-US From: Mario Limonciello In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 6/25/25 2:03 PM, Hans de Goede wrote: > Hi, > > On 25-Jun-25 8:13 PM, Mario Limonciello wrote: >> From: Mario Limonciello >> >> 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 >> } >> >> Many cherryview and baytrail systems don't have accurate values in the >> ASL for debouncing and thus use software debouncing in gpio_keys. The >> value to use is programmed in soc_button_array. Detect Cherry View >> and Baytrail using ACPI HID IDs used for those GPIO controllers and apply >> the 50ms only for those systems. >> >> Cc: Hans de Goede >> Fixes: 5c4fa2a6da7fb ("Input: soc_button_array - debounce the buttons") >> Signed-off-by: Mario Limonciello > > I'm not a fan of this approach, I believe that we need to always debounce > when dealing with mechanical buttons otherwise we will get unreliable / > spurious input events. > > My suggestion to deal with the issue where setting up debouncing at > the GPIO controller level is causing issues is to always use software > debouncing (which I suspect is what Windows does). > > Let me copy and pasting my reply from the v1 thread with > a bit more detail on my proposal: > > My proposal is to add a "no_hw_debounce" flag to > struct gpio_keys_platform_data and make the soc_button_array > driver set that regardless of which platform it is running on. > > And then in gpio_keys.c do something like this: > > diff --git a/drivers/input/keyboard/gpio_keys.c b/drivers/input/keyboard/gpio_keys.c > index f9db86da0818..2788d1e5782c 100644 > --- a/drivers/input/keyboard/gpio_keys.c > +++ b/drivers/input/keyboard/gpio_keys.c > @@ -552,8 +552,11 @@ static int gpio_keys_setup_key(struct platform_device *pdev, > bool active_low = gpiod_is_active_low(bdata->gpiod); > > if (button->debounce_interval) { > - error = gpiod_set_debounce(bdata->gpiod, > - button->debounce_interval * 1000); > + if (ddata->pdata->no_hw_debounce) > + error = -EINVAL; > + else > + error = gpiod_set_debounce(bdata->gpiod, > + button->debounce_interval * 1000); > /* use timer if gpiolib doesn't provide debounce */ > if (error < 0) > bdata->software_debounce = > > So keep debouncing, as that will always be necessary when dealing with > mechanical buttons, but always use software debouncing to avoid issues > like the issue you are seeing. > > My mention of the BYT/CHT behavior in my previous email was to point > out that those already always use software debouncing for the 50 ms > debounce-period. It was *not* my intention to suggest to solve this > with platform specific quirks/behavior. > > Regards, > > Hans I mentioned on the v1 too, but let's shift conversation here. So essentially all platforms using soc_button_array would always turn on software debouncing of 50ms? In that case what happens if the hardware debounce was ALSO set from the ASL? You end up with double debouncing I would expect. Shouldn't you only turn on software debouncing when it's required? I'm wondering if considering the first two patches we should have gpio-keys look up if hardware can support debounce, and then "only if it can't" we program the value from soc button array. It can be done by having gpio_keys do a "get()" on debounce. Iff the driver returns -ENOTSUPP /then/ program the software debounce.