Subject: [RFC PATCH 05/11] mfd: omap: control: core system control driver

From: [email-masked] (Cousson, Benoit)
Date: Tue, 29 May 2012 15:31:43 +0200

On 5/28/2012 3:15 PM, Shilimkar, Santosh wrote:
> On Mon, May 28, 2012 at 5:12 PM, Eduardo Valentin

[...]

>>>> +/**
>>>> + * omap_control_readl: Read a single omap control module register.
>>>> + *
>>>> + * @dev: device to read from.
>>>> + * @reg: register to read.
>>>> + * @val: output with register value.
>>>> + *
>>>> + * returns 0 on success or -EINVAL in case struct device is invalid.
>>>> + */
>>>> +int omap_control_readl(struct device *dev, u32 reg, u32 *val)
>>>> +{
>>>> +       struct omap_control *omap_control = dev_get_drvdata(dev);
>>>> +
>>>> +       if (!omap_control)
>>>> +               return -EINVAL;
>>>> +
>>>> +       *val = readl(omap_control->base + reg);
>>>> +
>>>> +       return 0;
>>>> +}
>>>> +EXPORT_SYMBOL_GPL(omap_control_readl);
>>>> +
>>> I might have missed in the last scan, but can you let
>>> function return the register value.
>>
>> Why?
>>
> Because thats how typical read 1 value kind of functions
> look like..

Yeah, I tend to agree with Santosh here as well. I'm expecting such API 
to return the value.
Moreover the error handling in that case is really an exception and thus 
a WARM is enough since it should never ever happen except if there is a 
bug during the probe. And in that case, it should already fail at probe 
time.

>>> I am guessing, you did this for error case handling. You might
>>> want to stick to read API semantic and just have WARN_ON()
>>> to take care of error case.
>>
>> Yeah, that was for error handling and to do not confuse register
>> values with error values.
>>
> No strong opinion if you like it that way but it just appeared odd to
> me from a caller perspective.

Yep, I do agree.

Benoit