[rtc-linux] Re: [PATCH] rtc-da9063: avoid writing undefined data to rtc

[Alexandre Belloni <alexandre.belloni@free-electrons.com>]

Hi,

On 27/11/2015 at 13:02:55 +0100, Enrico Scholz wrote :
> driver did
> 
> | static void da9063_tm_to_data(struct rtc_time *tm, u8 *data,
> | {
> |  	const struct da9063_compatible_rtc_regmap *config = rtc->config;
> |
> | 	data[RTC_SEC] &= ~config->rtc_count_sec_mask;
> | 	data[RTC_SEC] |= tm->tm_sec & config->rtc_count_sec_mask;
> | ...
> | }
> | ...
> | static int da9063_rtc_set_time(struct device *dev, struct rtc_time *tm)
> | {
> |       ...
> |	u8 data[RTC_DATA_LEN];
> |	int ret;
> |
> |	da9063_tm_to_data(tm, data, rtc);
> 
> which means that some bits of stack content (in 'data[]') was masked out
> and written to the RTC.
> 
> Because da9063_tm_to_data() is used only by da9063_rtc_set_time() and
> da9063_rtc_set_alarm(), we can write fields directly.
> 

Unfortunately, the datasheets are behind a register wall and I can't
check. Is there any meaningful bits mixed in the date/time registers?

I think this was intended to keep those bits to their previous value but
this is not yet implemented.

-- 
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

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