linux-kernel - Re: [v3,1/4] mfd: cros_ec: Add cros_ec_cmd_xfer

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Message-ID: <5765805A.5070407@roeck-us.net>
Date:	Sat, 18 Jun 2016 10:09:46 -0700
From:	Guenter Roeck <linux@...ck-us.net>
To:	Brian Norris <briannorris@...omium.org>
Cc:	Lee Jones <lee.jones@...aro.org>,
	Thierry Reding <thierry.reding@...il.com>,
	Olof Johansson <olof@...om.net>, linux-kernel@...r.kernel.org,
	Doug Anderson <dianders@...omium.org>,
	Brian Norris <computersforpeace@...il.com>,
	linux-pwm@...r.kernel.org, devicetree@...r.kernel.org,
	Boris Brezillon <boris.brezillon@...e-electrons.com>,
	Stephen Barber <smbarber@...omium.org>,
	Javier Martinez Canillas <javier@....samsung.com>,
	Benson Leung <bleung@...omium.org>,
	Enric Balletbo <enric.balletbo@...labora.co.uk>,
	Randall Spangler <rspangler@...omium.org>,
	Shawn Nematbakhsh <shawnn@...omium.org>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Todd Broch <tbroch@...omium.org>,
	Gwendal Grignou <gwendal@...omium.org>,
	Tomeu Vizoso <tomeu.vizoso@...labora.com>
Subject: Re: [v3,1/4] mfd: cros_ec: Add cros_ec_cmd_xfer_status helper

On 06/17/2016 06:08 PM, Brian Norris wrote:
> On Fri, Jun 17, 2016 at 02:41:51PM -0700, Guenter Roeck wrote:
>> On Fri, Jun 17, 2016 at 12:58:12PM -0700, Brian Norris wrote:
>>> +int cros_ec_cmd_xfer_status(struct cros_ec_device *ec_dev,
>>> +			    struct cros_ec_command *msg)
>>> +{
>>> +	int ret;
>>> +
>>> +	ret = cros_ec_cmd_xfer(ec_dev, msg);
>>> +	if (ret < 0)
>>> +		dev_err(ec_dev->dev, "Command xfer error (err:%d)\n", ret);
>>> +	else if (msg->result != EC_RES_SUCCESS)
>>> +		return -EECRESULT - msg->result;
>>
>> I have been wondering about the error return codes here, and if they should be
>> converted to standard Linux error codes. For example, I just hit error -1003
>> with a driver I am working on. This translates to EC_RES_INVALID_PARAM, or,
>> in Linux terms, -EINVAL. I think it would be better to use standard error
>> codes, especially since some of the errors are logged.
>
> How do you propose we do that? Do all of the following become EINVAL?
>
>          EC_RES_INVALID_COMMAND

	-EOPNOTSUPP

>          EC_RES_INVALID_PARAM

	-EINVAL or -EBADMSG

>          EC_RES_INVALID_VERSION

	-EPROTO or -EBADR or -EBADE or -EBADRQC or -EPROTOOPT

>          EC_RES_INVALID_HEADER

	-EPROTO or -EBADR or -EBADE

Doesn't look that bad to me. Also, the raw error could still be logged,
for example with dev_dbg().

Guenter

>
> We lose a lot of information that way. And particularly, cros_ec_num_pwms()
> won't be able to count as accurately. But I can just go back to not using this
> API if that's what you'd like...
>
> Brian
>