linux-kernel - Re: [PATCH v2] platform/chrome: Expose resume result via debugfs

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Message-ID: <20190625130515.GJ21119@dell>
Date:   Tue, 25 Jun 2019 14:05:15 +0100
From:   Lee Jones <lee.jones@...aro.org>
To:     Evan Green <evgreen@...omium.org>
Cc:     Enric Balletbo i Serra <enric.balletbo@...labora.com>,
        Ravi Chandra Sadineni <ravisadineni@...omium.org>,
        Rajat Jain <rajatja@...omium.org>,
        Guenter Roeck <groeck@...omium.org>,
        linux-kernel@...r.kernel.org, Benson Leung <bleung@...omium.org>,
        Tim Wawrzynczak <twawrzynczak@...omium.org>
Subject: Re: [PATCH v2] platform/chrome: Expose resume result via debugfs

On Mon, 17 Jun 2019, Evan Green wrote:

> For ECs that support it, the EC returns the number of slp_s0
> transitions and whether or not there was a timeout in the resume
> response. Expose the last resume result to usermode via debugfs so
> that usermode can detect and report S0ix timeouts.
> 
> Signed-off-by: Evan Green <evgreen@...omium.org>

This still needs a platform/chrome Ack.

> ---
> 
> Changes in v2:
>  - Moved from sysfs to debugfs (Enric)
>  - Added documentation (Enric)
> 
> 
> ---
>  Documentation/ABI/testing/debugfs-cros-ec | 22 ++++++++++++++++++++++
>  drivers/mfd/cros_ec.c                     |  6 +++++-
>  drivers/platform/chrome/cros_ec_debugfs.c |  7 +++++++
>  include/linux/mfd/cros_ec.h               |  1 +
>  4 files changed, 35 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/ABI/testing/debugfs-cros-ec b/Documentation/ABI/testing/debugfs-cros-ec
> index 573a82d23c89..008b31422079 100644
> --- a/Documentation/ABI/testing/debugfs-cros-ec
> +++ b/Documentation/ABI/testing/debugfs-cros-ec
> @@ -32,3 +32,25 @@ Description:
>  		is used for synchronizing the AP host time with the EC
>  		log. An error is returned if the command is not supported
>  		by the EC or there is a communication problem.
> +
> +What:		/sys/kernel/debug/cros_ec/last_resume_result
> +Date:		June 2019
> +KernelVersion:	5.3
> +Description:
> +		Some ECs have a feature where they will track transitions to
> +		the (Intel) processor's SLP_S0 line, in order to detect cases
> +		where a system failed to go into S0ix. When the system resumes,
> +		an EC with this feature will return a summary of SLP_S0
> +		transitions that occurred. The last_resume_result file returns
> +		the most recent response from the AP's resume message to the EC.
> +
> +		The bottom 31 bits contain a count of the number of SLP_S0
> +		transitions that occurred since the suspend message was
> +		received. Bit 31 is set if the EC attempted to wake the
> +		system due to a timeout when watching for SLP_S0 transitions.
> +		Callers can use this to detect a wake from the EC due to
> +		S0ix timeouts. The result will be zero if no suspend
> +		transitions have been attempted, or the EC does not support
> +		this feature.
> +
> +		Output will be in the format: "0x%08x\n".
> diff --git a/drivers/mfd/cros_ec.c b/drivers/mfd/cros_ec.c
> index 5d5c41ac3845..2a9ac5213893 100644
> --- a/drivers/mfd/cros_ec.c
> +++ b/drivers/mfd/cros_ec.c
> @@ -102,12 +102,16 @@ static int cros_ec_sleep_event(struct cros_ec_device *ec_dev, u8 sleep_event)
>  
>  	/* For now, report failure to transition to S0ix with a warning. */
>  	if (ret >= 0 && ec_dev->host_sleep_v1 &&
> -	    (sleep_event == HOST_SLEEP_EVENT_S0IX_RESUME))
> +	    (sleep_event == HOST_SLEEP_EVENT_S0IX_RESUME)) {
> +		ec_dev->last_resume_result =
> +			buf.u.resp1.resume_response.sleep_transitions;
> +
>  		WARN_ONCE(buf.u.resp1.resume_response.sleep_transitions &
>  			  EC_HOST_RESUME_SLEEP_TIMEOUT,
>  			  "EC detected sleep transition timeout. Total slp_s0 transitions: %d",
>  			  buf.u.resp1.resume_response.sleep_transitions &
>  			  EC_HOST_RESUME_SLEEP_TRANSITIONS_MASK);
> +	}
>  
>  	return ret;
>  }
> diff --git a/drivers/platform/chrome/cros_ec_debugfs.c b/drivers/platform/chrome/cros_ec_debugfs.c
> index cd3fb9c22a44..663bebf699bf 100644
> --- a/drivers/platform/chrome/cros_ec_debugfs.c
> +++ b/drivers/platform/chrome/cros_ec_debugfs.c
> @@ -447,6 +447,13 @@ static int cros_ec_debugfs_probe(struct platform_device *pd)
>  	debugfs_create_file("uptime", 0444, debug_info->dir, debug_info,
>  			    &cros_ec_uptime_fops);
>  
> +	if (!strcmp(ec->class_dev.kobj.name, CROS_EC_DEV_NAME)) {
> +		debugfs_create_x32("last_resume_result",
> +				   0444,
> +				   debug_info->dir,
> +				   &ec->ec_dev->last_resume_result);
> +	}
> +
>  	ec->debug_info = debug_info;
>  
>  	dev_set_drvdata(&pd->dev, ec);
> diff --git a/include/linux/mfd/cros_ec.h b/include/linux/mfd/cros_ec.h
> index 5ddca44be06d..45aba26db964 100644
> --- a/include/linux/mfd/cros_ec.h
> +++ b/include/linux/mfd/cros_ec.h
> @@ -155,6 +155,7 @@ struct cros_ec_device {
>  	struct ec_response_get_next_event_v1 event_data;
>  	int event_size;
>  	u32 host_event_wake_mask;
> +	u32 last_resume_result;
>  };
>  
>  /**

-- 
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
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