linux-kernel - Re: [PATCH] ACPI / PM: Fix wake up by PS2 keyboard fail on ASUS UX331UA

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Date:   Mon, 02 Apr 2018 13:00:16 +0200
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Chris Chiu <chiu@...lessm.com>
Cc:     lenb@...nel.org, linux-acpi@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux@...lessm.com
Subject: Re: [PATCH] ACPI / PM: Fix wake up by PS2 keyboard fail on ASUS UX331UA

On Saturday, March 31, 2018 4:09:31 AM CEST Chris Chiu wrote:
> This issue happens on new ASUS laptop UX331UA which has modern
> standby mode (suspend-to-idle). Pressing keys on the PS2 keyboard
> can't wake up the system from suspend-to-idle which is not expected.
> However, pressing power button can wake up without problem.
> 
> Per the engineers of ASUS, the keypress event is routed to Embedded
> Controller (EC) in standby mode. EC then signals the SCI event to
> BIOS so BIOS would Notify() power button to wake up the system. It's
> from BIOS perspective. What we observe here is that kernel receives
> the SCI event from SCI interrupt handler which informs that the GPE
> status bit belongs to EC needs to be handled and then queries the EC
> to find out what event is pending. Then execute the following ACPI
> _QDF method which defined in ACPI DSDT for EC to notify power button.
> 
>  Method (_QDF, 0, NotSerialized)  // _Qxx: EC Query
>         {
>             Notify (PWRB, 0x80) // Status Change
>         }
> 
> With more debug messages added to analyze this problem, we find that
> the keypress does wake up the system from suspend-to-idle but it's back
> to suspend again almost immediately. As we see in the following messages,
> the acpi_button_notify() is invoked but acpi_pm_wakeup_event() can not
> really wake up the system here because acpi_s2idle_wakeup() is false.
> The acpi_s2idle_wakeup() returnd false because the acpi_s2idle_sync() has
> alrealdy exited.
> 
> [   52.987048] s2idle_loop going s2idle
> [   59.713392] acpi_s2idle_wake enter
> [   59.713394] acpi_s2idle_wake exit
> [   59.760888] acpi_ev_gpe_detect enter
> [   59.760893] acpi_s2idle_sync enter
> [   59.760893] acpi_ec_query_flushed ec pending queries 0
> [   59.760953] Read registers for GPE 50-57: Status=01, Enable=01, RunEnable=01, WakeEnable=00
> [   59.760955] ACPI: EC: ===== IRQ (1) =====
> [   59.760972] ACPI: EC: EC_SC(R) = 0x28 SCI_EVT=1 BURST=0 CMD=1 IBF=0 OBF=0
> [   59.760979] ACPI: EC: +++++ Polling enabled +++++
> [   59.760979] ACPI: EC: ##### Command(QR_EC) submitted/blocked #####
> [   59.761003] acpi_s2idle_sync exit
> [   59.769587] ACPI: EC: ##### Query(0xdf) started #####
> [   59.769611] ACPI: EC: ##### Query(0xdf) stopped #####
> [   59.774154] acpi_button_notify button type 1
> [   59.813175] s2idle_loop going s2idle
> 
> acpi_s2idle_sync() already makes an effort to flush the EC event
> queue, but in this case, the EC event has yet to be generated when
> the call to acpi_ec_flush_work() is made. The event is generated
> shortly after, through the ongoing handling of the SCI interrupt
> which is happening on another CPU, and we must synchronize that
> to make sure that it has run and completed. Adding another call to
> acpi_os_wait_events_complete() solves this issue, since that
> function synchronizes with SCI interrupt completion.
> 
> Signed-off-by: Chris Chiu <chiu@...lessm.com>
> 
> ---
>  drivers/acpi/sleep.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/acpi/sleep.c b/drivers/acpi/sleep.c
> index 8082871..c6e1b4b 100644
> --- a/drivers/acpi/sleep.c
> +++ b/drivers/acpi/sleep.c
> @@ -982,8 +982,9 @@ static void acpi_s2idle_sync(void)
>  	 * The EC driver uses the system workqueue and an additional special
>  	 * one, so those need to be flushed too.
>  	 */
> +	acpi_os_wait_events_complete();	/* synchronize SCI IRQ handling */
>  	acpi_ec_flush_work();
> -	acpi_os_wait_events_complete();
> +	acpi_os_wait_events_complete();	/* synchronize Notify handling */
>  	s2idle_wakeup = false;
>  }
>  
> 
Applied, thanks!