Re: [rtc-linux] [PATCH 2/2] rtc: mediatek: Add MT63xx RTC driver

[Sascha Hauer]

Hi Eddie,

On Fri, Mar 13, 2015 at 06:29:23PM +0800, Eddie Huang wrote:
> > regmap_read() and regmap_write() can return errors.  There is no
> > checking for this.
> > 
> 
> I encounter some trouble when I add code to check return value of
> regmap_read and regmap_write. Every RTC register access through regmap,
> and there are many register read/write in this driver. If I check every
> return value, the driver will become ugly. I try to make this driver
> clean using following macro.
> 
> static int __rtc_read(struct mt6397_rtc *rtc, u32 offset, u32 *data)
> {
>         u32 addr = rtc->addr_base + offset;
> 
>         if (offset < rtc->addr_range)
>                 return regmap_read(rtc->regmap, addr, data);
> 
>         return -EINVAL;
> }
> 
> #define rtc_read(ret, rtc, offset, data)                \
> ({                                                      \
>         ret = __rtc_read(rtc, offset, data);            \
>         if (ret < 0)                                    \
>                 goto rtc_exit;                          \
> })                                                      \

Hiding a goto (or return) in a macro is a very bad idea.

what you can do is

	ret |= regmap_read(rtc->regmap, RTC_TC_SEC, &tm->tm_sec);
	ret |= regmap_read(rtc->regmap, RTC_TC_MIN, &tm->tm_min);

	if (ret)
		return -EIO;

(Don't return ret in this case though as it might contain different
error codes orred together)

Another possibilty at least for contiguous registers would be
regmap_bulk_read().

Sascha

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