[LinuxPPS] PPS SC16IS7X2

[Igor Plyatov]

Hello Nial!

Please be aware, because you will have big jitter between real PPS 
signal and registered event. All this problems related to sloth nature 
of I2C bus and its kernel driver (especially if UART does not have 
hardware IRQ line).

>
> > If your device is uart compatible yes, otherwise you must implement
> > the code inside the uart_handle_dcd_change for your serial driver
> > which, in turn, calls the TTY's dcd_change.
>
> Ok, I had a go at this over the weekend. The device is uart 
> compatible, so I found where the handle_tx and handle_rx functions 
> were in the driver and added a handle_dcd function which checks the 
> status of the DDCD bit in the MSR register and then calls 
> uart_handle_dcd_change if needed. However, it doesn't work! The whole 
> MSR register is always 0 for some reason. I checked to see if the 
> modem status interrupt bit was set in the IER register and it is (at 
> least it is after you call ldattach on the port). Does anyone have any 
> bright ideas on what I might be missing?
>
> Thanks a lot,
> Nial

-- 

Igor Plyatov