Wolfgang Denk schrieb:
Dear "Reinhard Meyer (-VC)",
In message 4C31C596.5020905@emk-elektronik.de you wrote:
cmd_data.c codes the following:
...
rcode = rtc_get (&tm); if(!rcode) { /* insert new date & time */ if (mk_date (argv[1], &tm) != 0) { puts ("## Bad date format\n"); break; } /* and write to RTC */ rcode = rtc_set (&tm); if(rcode) puts("## Set date failed\n"); } else { puts("## Get date failed\n"); }...
Now I have implemented rtc_get() such that it returns an error code when the time is corrupt/has never been set.
It is considered kind of "normal" that a RTC may return "corrupt" data. This is not an error, as it will be fixed when setting the date. An error condition is something that really makes the RTC unusable, like non-functioning communication on the I2C bus (if your RTC is connected to that), or reading a Low Voltage error status from the RTC status register, etc.
However the "if(!rcode)" then prevents the time to be set!
Well, if you cannot eliably communicate with the RTC when reading, there is little sense trying to write to it - on contrary, this might even be dangerous.
Is that intentional and rtc_get() should never return an error ?? Or is it an oversight, and a patch would be welcome ?
The behaviour is intentional, but rtc_get() can of course return error codes - only your expectation when this is the case is different from mine.
Dear Wolfgang,
of course that depends on what is considered an error.
As well as there is a difference between read error and file not found, there well might be a difference in clock nonfunctional and time invalid...
But alas, I will make rtc_get not return an error and zero out the tm structure instead when the driver KNOWS the date is not correct.
And btw. a low voltage status error from the clock does not necessaryly mean the clock cannot be set again, that status (and thats exactly what I intended to return) just could mean that the backup voltage was too low during a system unpowered time to guarantee a proper date but since (in our case) the backup power comes from a GoldCap a new set of the clock would heal that status.
And if the clock really would be defective /* and write to RTC */ rcode = rtc_set (&tm); if(rcode) puts("## Set date failed\n"); would still give a proper error message!
Reinhard