linux-kernel - Re: [RESEND PATCH v7 3/6] mfd: cros_ec: Add cros_ec_get_host

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Date:	Mon, 11 Apr 2016 12:23:03 +0100
From:	Lee Jones <lee.jones@...aro.org>
To:	Tomeu Vizoso <tomeu.vizoso@...labora.com>
Cc:	linux-kernel@...r.kernel.org, Sameer Nanda <snanda@...omium.org>,
	Javier Martinez Canillas <javier@....samsung.com>,
	Benson Leung <bleung@...omium.org>,
	Enric Balletbò 
	<enric.balletbo@...labora.co.uk>,
	Vic Yang <victoryang@...omium.org>,
	Stephen Boyd <sboyd@...eaurora.org>,
	Vincent Palatin <vpalatin@...omium.org>,
	Randall Spangler <rspangler@...omium.org>,
	Todd Broch <tbroch@...omium.org>,
	Gwendal Grignou <gwendal@...omium.org>,
	Olof Johansson <olof@...om.net>
Subject: Re: [RESEND PATCH v7 3/6] mfd: cros_ec: Add cros_ec_get_host_event

On Tue, 05 Apr 2016, Tomeu Vizoso wrote:

> This function returns the code for the host event that triggered the
> interrupt that is being currently handled.
> 
> Is to be used by observers of the event_notifier in the EC device.
> 
> Signed-off-by: Tomeu Vizoso <tomeu.vizoso@...labora.com>
> ---
> 
> Changes in v7: None
> Changes in v6:
> - Return 0 if the EC doesn't support MKBP, as expected by callers.
> 
> Changes in v5: None
> Changes in v4: None
> Changes in v3: None
> Changes in v2: None
> 
>  drivers/platform/chrome/cros_ec_proto.c | 23 +++++++++++++++++++++++
>  include/linux/mfd/cros_ec.h             | 10 ++++++++++
>  2 files changed, 33 insertions(+)
> 
> diff --git a/drivers/platform/chrome/cros_ec_proto.c b/drivers/platform/chrome/cros_ec_proto.c
> index aaccdde1c9d5..3e1e83874edf 100644
> --- a/drivers/platform/chrome/cros_ec_proto.c
> +++ b/drivers/platform/chrome/cros_ec_proto.c
> @@ -486,3 +486,26 @@ int cros_ec_cmd_xfer_status(struct cros_ec_device *ec_dev,
>  	return ret;
>  }
>  EXPORT_SYMBOL(cros_ec_cmd_xfer_status);
> +
> +u32 cros_ec_get_host_event(struct cros_ec_device *ec_dev)
> +{
> +	u32 host_event;
> +
> +	if (!ec_dev->mkbp_event_supported) {
> +		dev_warn(ec_dev->dev,
> +			 "This EC does not support EC_MKBP_EVENT_HOST_EVENT");
> +		return 0;
> +	}
> +
> +	if (ec_dev->event_data.event_type != EC_MKBP_EVENT_HOST_EVENT)
> +		return 0;
> +
> +	if (ec_dev->event_size != sizeof(host_event)) {
> +		dev_warn(ec_dev->dev, "Invalid host event size\n");
> +		return 0;
> +	}
> +
> +	host_event = get_unaligned_le32(&ec_dev->event_data.data.host_event);

This assignment is pointless.  Just return right away.

> +	return host_event;
> +}
> +EXPORT_SYMBOL(cros_ec_get_host_event);
> diff --git a/include/linux/mfd/cros_ec.h b/include/linux/mfd/cros_ec.h
> index e4c4c0480c14..9dd2c6711ea9 100644
> --- a/include/linux/mfd/cros_ec.h
> +++ b/include/linux/mfd/cros_ec.h
> @@ -304,6 +304,16 @@ int cros_ec_query_all(struct cros_ec_device *ec_dev);
>   */
>  int cros_ec_get_next_event(struct cros_ec_device *ec_dev);
>  
> +/**
> + * cros_ec_get_host_event - Return a mask of event set by the EC.
> + *
> + * Returns the mask of the event that caused the last interrupt to be raised.
> + *
> + * @ec_dev: Device to fetch event from
> + * @return event mask, 0 on error

s/@...urn/Returns:/

"Event mask on success"

I have a few problems with "0 on error".  Please reword so it doesn't
looks like we're returning "success on error".  I suggest, if you're
not returning >0, that it's not really an error, so drop the word.

> + */
> +uint32_t cros_ec_get_host_event(struct cros_ec_device *ec_dev);
> +
>  /* sysfs stuff */
>  extern struct attribute_group cros_ec_attr_group;
>  extern struct attribute_group cros_ec_lightbar_attr_group;

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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