linux-kernel - Re: intel-vbtn: match power button on press rather than release

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Date:   Sat, 16 Sep 2017 15:45:38 +0200
From:   Pali Rohár <pali.rohar@...il.com>
To:     Mario Limonciello <mario.limonciello@...l.com>,
        dvhart@...radead.org, Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:     AceLan Kao <acelan.kao@...onical.com>, linux-pm@...r.kernel.org,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        LKML <linux-kernel@...r.kernel.org>,
        platform-driver-x86@...r.kernel.org, Len Brown <lenb@...nel.org>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
Subject: Re: intel-vbtn: match power button on press rather than release

On Friday 04 August 2017 19:00:06 Mario Limonciello wrote:
> This fixes a problem where the system gets stuck in a loop
> unable to wakeup via power button in s2idle.
> 
> The problem happens because:
>  - press power button:
>    - system emits 0xc0 (power press), event ignored
>    - system emits 0xc1 (power release), event processed,
>      emited as KEY_POWER
>    - set wakeup_mode to true
>    - system goes to s2idle
>  - press power button
>    - system emits 0xc0 (power press), wakeup_mode is true,
>      system wakes
>    - system emits 0xc1 (power release), event processed,
>      emited as KEY_POWER
>    - system goes to s2idle again
> 
> To avoid this situation, process the presses (which matches what
> intel-hid does too).
> 
> Verified on an Dell XPS 9365
> 
> Signed-off-by: Mario Limonciello <mario.limonciello@...l.com>
> ---
>  drivers/platform/x86/intel-vbtn.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/platform/x86/intel-vbtn.c
> b/drivers/platform/x86/intel-vbtn.c index 61f1063..4809267 100644
> --- a/drivers/platform/x86/intel-vbtn.c
> +++ b/drivers/platform/x86/intel-vbtn.c
> @@ -36,8 +36,8 @@ static const struct acpi_device_id intel_vbtn_ids[]
> = {
> 
>  /* In theory, these are HID usages. */
>  static const struct key_entry intel_vbtn_keymap[] = {
> -	{ KE_IGNORE, 0xC0, { KEY_POWER } },	/* power key press */
> -	{ KE_KEY, 0xC1, { KEY_POWER } },	/* power key release */
> +	{ KE_KEY, 0xC0, { KEY_POWER } },	/* power key press */
> +	{ KE_IGNORE, 0xC1, { KEY_POWER } },	/* power key release */
>  	{ KE_KEY, 0xC4, { KEY_VOLUMEUP } },		/* volume-up key press */
>  	{ KE_IGNORE, 0xC5, { KEY_VOLUMEUP } },		/* volume-up key release 
*/
>  	{ KE_KEY, 0xC6, { KEY_VOLUMEDOWN } },		/* volume-down key press */

Hello, maybe a stupid question, but why to not report both events "key 
pressed" and "key released" to userspace? IIRC kernel input layer can 
distinguish between these two type of events. But in intel-vbtn.c source 
code I see that all "release" ACPI events are ignored and just "press" 
are processed.

-- 
Pali Rohár
pali.rohar@...il.com

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