Re: [PATCH V6 2/2] rtc: zynqmp: Add calibration set and get support

From: Peter Korsgaard
Date: Thu Jun 09 2022 - 11:00:02 EST


>>>>> "Alexandre" == Alexandre Belloni <alexandre.belloni@xxxxxxxxxxx> writes:

> On 09/06/2022 16:50:03+0200, Peter Korsgaard wrote:
>> >>>>> "Srinivas" == Srinivas Neeli <srinivas.neeli@xxxxxxxxxx> writes:
>>
>> > Zynqmp RTC controller has a calibration feature to compensate
>> > time deviation due to input clock inaccuracy.
>> > Set and get calibration API's are used for setting and getting
>> > calibration value from the controller calibration register.
>> > As per RTC spec default calibration value is 0x7FFF.
>>
>> Where do you see that? ug1085 rev2.2 still lists:
>>
>> Programming Sequences
>> init rtc
>> 1. Write the value 0019_8231h into the calibration register, CALIB_WRITE.
>>

> This is a very weird value. Last time I had a look, I couldn't find an
> explanation for it.

Agreed. I am not arguing that it is sensible, I just wondered where this
new value comes from?

--
Bye, Peter Korsgaard