[PATCH net v3] net: ti: icssg-prueth: Fix 1 PPS sync

[Malladi, Meghana]

On 11/1/2024 7:29 AM, Jakub Kicinski wrote:
> On Mon, 28 Oct 2024 16:40:52 +0530 Meghana Malladi wrote:
>> The first PPS latch time needs to be calculated by the driver
>> (in rounded off seconds) and configured as the start time
>> offset for the cycle. After synchronizing two PTP clocks
>> running as master/slave, missing this would cause master
>> and slave to start immediately with some milliseconds
>> drift which causes the PPS signal to never synchronize with
>> the PTP master.
> 
> You're reading a 64b value in chunks, is it not possible that it'd wrap
> in between reads? This can be usually detected by reading high twice and
> making sure it didn't change.
> 
> Please fix or explain in the commit message why this is not a problem..
Yes I agree that there might be a wrap if the read isn't atomic. As 
suggested by Andrew I am currently not using custom read where I can 
implement the logic you suggested (reading high twice and making sure if 
didn't change). Can you share me some references where this logic is 
implemented in the kernel, so I can directly use that instead of writing 
custom functions.

Regards,
Meghana.