linux-kernel - Re: [PATCH] ACPI / PM / EC: Flush all EC work in acpi_freeze

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Message-ID: <1957572.97AlN5W1uF@aspire.rjw.lan>
Date:   Thu, 20 Jul 2017 23:53:51 +0200
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Linux ACPI <linux-acpi@...r.kernel.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Lv Zheng <lv.zheng@...el.com>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
Subject: Re: [PATCH] ACPI / PM / EC: Flush all EC work in acpi_freeze_sync()

On Thursday, July 20, 2017 03:43:12 AM Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> 
> Commit eed4d47efe95 (ACPI / sleep: Ignore spurious SCI wakeups from
> suspend-to-idle) introduced acpi_freeze_sync() whose purpose is to
> flush all of the processing of possible wakeup events signaled via
> the ACPI SCI.  However, it doesn't flush the query workqueue used
> by the EC driver, so the events generated by the EC may not be
> processed timely which leads to issues (increased overhead at least,
> lost events possibly).
> 
> To fix that introduce acpi_ec_flush_work() that will flush all of
> the outstanding EC work and call it from acpi_freeze_sync().
> 
> Fixes: eed4d47efe95 (ACPI / sleep: Ignore spurious SCI wakeups from suspend-to-idle)
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

If there are any issues related to this, please let me know.

Otherwise, I'll queue it up as a fix for 4.13.

> ---
>  drivers/acpi/ec.c       |    8 ++++++++
>  drivers/acpi/internal.h |    4 ++++
>  drivers/acpi/sleep.c    |    6 +++---
>  3 files changed, 15 insertions(+), 3 deletions(-)
> 
> Index: linux-pm/drivers/acpi/ec.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/ec.c
> +++ linux-pm/drivers/acpi/ec.c
> @@ -539,6 +539,14 @@ static void acpi_ec_disable_event(struct
>  	spin_unlock_irqrestore(&ec->lock, flags);
>  	__acpi_ec_flush_event(ec);
>  }
> +
> +void acpi_ec_flush_work(void)
> +{
> +	if (first_ec)
> +		__acpi_ec_flush_event(first_ec);
> +
> +	flush_scheduled_work();
> +}
>  #endif /* CONFIG_PM_SLEEP */
>  
>  static bool acpi_ec_guard_event(struct acpi_ec *ec)
> Index: linux-pm/drivers/acpi/internal.h
> ===================================================================
> --- linux-pm.orig/drivers/acpi/internal.h
> +++ linux-pm/drivers/acpi/internal.h
> @@ -193,6 +193,10 @@ int acpi_ec_add_query_handler(struct acp
>  			      void *data);
>  void acpi_ec_remove_query_handler(struct acpi_ec *ec, u8 query_bit);
>  
> +#ifdef CONFIG_PM_SLEEP
> +void acpi_ec_flush_work(void);
> +#endif
> +
>  
>  /*--------------------------------------------------------------------------
>                                    Suspend/Resume
> Index: linux-pm/drivers/acpi/sleep.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/sleep.c
> +++ linux-pm/drivers/acpi/sleep.c
> @@ -777,11 +777,11 @@ static void acpi_freeze_sync(void)
>  	/*
>  	 * Process all pending events in case there are any wakeup ones.
>  	 *
> -	 * The EC driver uses the system workqueue, so that one needs to be
> -	 * flushed too.
> +	 * The EC driver uses the system workqueue and an additional special
> +	 * one, so those need to be flushed too.
>  	 */
> +	acpi_ec_flush_work();
>  	acpi_os_wait_events_complete();
> -	flush_scheduled_work();
>  	s2idle_wakeup = false;
>  }
>  
> 
> --
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