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Date:   Tue, 13 Nov 2018 21:33:47 -0800
From:   Benson Leung <bleung@google.com>
To:     Brian Norris <briannorris@chromium.org>
Cc:     Benson Leung <bleung@chromium.org>,
        Lee Jones <lee.jones@linaro.org>, linux-kernel@vger.kernel.org,
        Olof Johansson <olof@lixom.net>,
        Shawn Nematbakhsh <shawnn@chromium.org>,
        Alexandru Stan <amstan@chromium.org>,
        Gwendal Grignou <gwendal@chromium.org>,
        Enrico Granata <egranata@chromium.org>,
        RaviChandra Sadineni <ravisadineni@chromium.org>
Subject: Re: [PATCH v2 1/2] platform/chrome: straighten out
 cros_ec_get_{next,host}_event() error codes
Message-ID: <20181114053347.GA145716@google.com>
References: <20181108024939.174321-1-briannorris@chromium.org>
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Hi Brian,

On Wed, Nov 07, 2018 at 06:49:38PM -0800, Brian Norris wrote:
> cros_ec_get_next_event() is documented to return 0 for success and
> negative for errors. It currently returns negative for some errors, and
> non-negative (number of bytes received) for success (including some "no
> data available" responses as zero). This mostly works out OK, because the
> callers were more or less ignoring the documentation, and only treating
> positive values as success (and indepdently checking the modification of
> 'wakeup').
>=20
> Let's button this up by avoiding pretending to handle event/wakeup
> distinctions when no event info was retrieved (i.e., returned 0 bytes).
> And fix the documentation of cros_ec_get_host_event() and
> cros_ec_get_next_event() to accurately describe their behavior.
>=20
> Signed-off-by: Brian Norris <briannorris@chromium.org>

Applied.

Thanks,
Benson

> ---
> v1 -> v2:
>  * don't make as many changes to the API -- just fix the documentation
>    and a few corner cases instead
> ---
>  drivers/platform/chrome/cros_ec_proto.c | 4 ++--
>  include/linux/mfd/cros_ec.h             | 6 ++++--
>  2 files changed, 6 insertions(+), 4 deletions(-)
>=20
> diff --git a/drivers/platform/chrome/cros_ec_proto.c b/drivers/platform/c=
hrome/cros_ec_proto.c
> index b6fd4838f60f..fff67b389c87 100644
> --- a/drivers/platform/chrome/cros_ec_proto.c
> +++ b/drivers/platform/chrome/cros_ec_proto.c
> @@ -580,7 +580,7 @@ int cros_ec_get_next_event(struct cros_ec_device *ec_=
dev, bool *wake_event)
> =20
>  	if (!ec_dev->mkbp_event_supported) {
>  		ret =3D get_keyboard_state_event(ec_dev);
> -		if (ret < 0)
> +		if (ret <=3D 0)
>  			return ret;
> =20
>  		if (wake_event)
> @@ -590,7 +590,7 @@ int cros_ec_get_next_event(struct cros_ec_device *ec_=
dev, bool *wake_event)
>  	}
> =20
>  	ret =3D get_next_event(ec_dev);
> -	if (ret < 0)
> +	if (ret <=3D 0)
>  		return ret;
> =20
>  	if (wake_event) {
> diff --git a/include/linux/mfd/cros_ec.h b/include/linux/mfd/cros_ec.h
> index e44e3ec8a9c7..de8b588c8776 100644
> --- a/include/linux/mfd/cros_ec.h
> +++ b/include/linux/mfd/cros_ec.h
> @@ -317,7 +317,9 @@ int cros_ec_query_all(struct cros_ec_device *ec_dev);
>   * @wake_event: Pointer to a bool set to true upon return if the event m=
ight be
>   *              treated as a wake event. Ignored if null.
>   *
> - * Return: 0 on success or negative error code.
> + * Return: negative error code on errors; 0 for no data; or else number =
of
> + * bytes received (i.e., an event was retrieved successfully). Event typ=
es are
> + * written out to @ec_dev->event_data.event_type on success.
>   */
>  int cros_ec_get_next_event(struct cros_ec_device *ec_dev, bool *wake_eve=
nt);
> =20
> @@ -329,7 +331,7 @@ int cros_ec_get_next_event(struct cros_ec_device *ec_=
dev, bool *wake_event);
>   * events raised and call the functions in the ec notifier. This function
>   * is a helper to know which events are raised.
>   *
> - * Return: 0 on success or negative error code.
> + * Return: 0 on error or non-zero bitmask of one or more EC_HOST_EVENT_*.
>   */
>  u32 cros_ec_get_host_event(struct cros_ec_device *ec_dev);
> =20
> --=20
> 2.19.1.930.g4563a0d9d0-goog
>=20

--=20
Benson Leung
Staff Software Engineer
Chrome OS Kernel
Google Inc.
bleung@google.com
Chromium OS Project
bleung@chromium.org

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