linux-kernel - Re: [PATCH v2 2/2] platform/chrome: don't report EC_MKBP_EVENT_SENSOR

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Date:   Tue, 13 Nov 2018 21:34:45 -0800
From:   Benson Leung <bleung@...gle.com>
To:     Brian Norris <briannorris@...omium.org>
Cc:     Benson Leung <bleung@...omium.org>,
        Lee Jones <lee.jones@...aro.org>, linux-kernel@...r.kernel.org,
        Olof Johansson <olof@...om.net>,
        Shawn Nematbakhsh <shawnn@...omium.org>,
        Alexandru Stan <amstan@...omium.org>,
        Gwendal Grignou <gwendal@...omium.org>,
        Enrico Granata <egranata@...omium.org>,
        RaviChandra Sadineni <ravisadineni@...omium.org>
Subject: Re: [PATCH v2 2/2] platform/chrome: don't report
 EC_MKBP_EVENT_SENSOR_FIFO as wakeup

Hi Brian,

On Wed, Nov 07, 2018 at 06:49:39PM -0800, Brian Norris wrote:
> EC_MKBP_EVENT_SENSOR_FIFO events can be triggered for a variety of
> reasons, and there are very few cases in which they should be treated as
> wakeup interrupts (particularly, when a certain
> MOTIONSENSE_MODULE_FLAG_* is set, but this is not even supported in the
> mainline cros_ec_sensor driver yet). Most of the time, they are benign
> sensor readings. In any case, the top-level cros_ec device doesn't know
> enough to determine that they should wake the system, and so it should
> not report the event. This would be the job of the cros_ec_sensors
> driver to parse.
> 
> This patch adds checks to cros_ec_get_next_event() such that it doesn't
> signal 'wakeup' for events of type EC_MKBP_EVENT_SENSOR_FIFO.
> 
> This patch is particularly relevant on devices like Scarlet (Rockchip
> RK3399 tablet, known as Acer Chromebook Tab 10), where the EC firmware
> reports sensor events much more frequently. This was causing
> /sys/power/wakeup_count to increase very frequently, often needlessly
> interrupting our ability to suspend the system.
> 
> Signed-off-by: Brian Norris <briannorris@...omium.org>

Applied. Thanks!

Benson

> ---
> v1 -> v2:
>  * no change
> ---
>  drivers/platform/chrome/cros_ec_proto.c | 18 +++++++++++++++---
>  1 file changed, 15 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/platform/chrome/cros_ec_proto.c b/drivers/platform/chrome/cros_ec_proto.c
> index fff67b389c87..cc7baf0ecb3c 100644
> --- a/drivers/platform/chrome/cros_ec_proto.c
> +++ b/drivers/platform/chrome/cros_ec_proto.c
> @@ -575,6 +575,7 @@ static int get_keyboard_state_event(struct cros_ec_device *ec_dev)
>  
>  int cros_ec_get_next_event(struct cros_ec_device *ec_dev, bool *wake_event)
>  {
> +	u8 event_type;
>  	u32 host_event;
>  	int ret;
>  
> @@ -594,11 +595,22 @@ int cros_ec_get_next_event(struct cros_ec_device *ec_dev, bool *wake_event)
>  		return ret;
>  
>  	if (wake_event) {
> +		event_type = ec_dev->event_data.event_type;
>  		host_event = cros_ec_get_host_event(ec_dev);
>  
> -		/* Consider non-host_event as wake event */
> -		*wake_event = !host_event ||
> -			      !!(host_event & ec_dev->host_event_wake_mask);
> +		/*
> +		 * Sensor events need to be parsed by the sensor sub-device.
> +		 * Defer them, and don't report the wakeup here.
> +		 */
> +		if (event_type == EC_MKBP_EVENT_SENSOR_FIFO)
> +			*wake_event = false;
> +		/* Masked host-events should not count as wake events. */
> +		else if (host_event &&
> +			 !(host_event & ec_dev->host_event_wake_mask))
> +			*wake_event = false;
> +		/* Consider all other events as wake events. */
> +		else
> +			*wake_event = true;
>  	}
>  
>  	return ret;
> -- 
> 2.19.1.930.g4563a0d9d0-goog
> 

-- 
Benson Leung
Staff Software Engineer
Chrome OS Kernel
Google Inc.
bleung@...gle.com
Chromium OS Project
bleung@...omium.org

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