On Wed, Apr 15, 2015 at 03:13:53PM +0200, Gregory CLEMENT wrote:
> While setting the time, the RTC TIME register should not be
> accessed. However due to hardware constraints, setting the RTC time
> involves sleeping during 100ms. This sleep was done outside the
> critical section protected by the spinlock, so it was possible to read
> the RTC TIME register and get an incorrect value. This patch
> introduces a mutex for protecting the RTC TIME access, unlike the
> spinlock it is allowed to sleep in a critical section protected by a
> mutex. The RTC STATUS register can still be used from the interrupt
> handler but it has no effect on setting the time.
Hi Gregory
There is the following comment in the code:
/*
* Setting the RTC time not always succeeds. According to the
* errata we need to first write on the status register and
* then wait for 100ms before writing to the time register to be
* sure that the data will be taken into account.
*/
The interrupt handler also writes to the STATUS register. So what
happens if there is an interrupt during that 100ms and a second write
to STATUS?
Maybe it is necessary to disable the RTC interrupt while setting the
time?
Andrew
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