[LinuxPPS] http://lkml.org/lkml/2008/4/11/42

[Rodolfo Giometti]

On Fri, Apr 11, 2008 at 11:02:43AM +0200, Bernhard Schiffner wrote:
> Hi Rodolfo,
> 
> thanks for stepping up again. Seems the only opponent (of details) is Alan 
> Cox now. Congrats so far.
> 
> But the details he is speaking of are IMHO crucial to linuxpps. That's why 
> I'am writing this message.
> 
> [snip]

As already stated into my previous e-mail the problem has a better
solution in hardware, not in software.

IMHO the serial solution is a cheap-but-weak PPS implementation, we
can move the pps_event() as before as we wish but the results will
remain poor... a really *good* solution will be doing a dedicated
hardware where serial data are still collected by a serial port but
the PPS signal is routed directly to a CPU's pin.

For example ARM systems has Fast Interrupt (FIQ) which are something
similar to non-maskerable IRQ (NMI)... a dedicated system where on the
same board lie the arm CPU *and* the GPS antenna and where the PPS
signal is managed by a FIQ irq handler is the best we can do in
hardware and software! :)

Ciao,

Rodolfo

-- 

GNU/Linux Solutions                  e-mail:    giometti at enneenne.com
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