Re: Fw: [3.18.3] poll() on gpio pins broken

[folkert <folkert@xxxxxxxxxxxxxx>]

Michael,

> > For timekeeping I wrote a program which waits for interrupts on
> > gpio-pins and then tells the local ntp daemon the clock offset.
> > I'm aware of the pps support in recent kernel but that does not work
> > (yet) on all platforms (eg cubieboard 1).
> > 
> > This has worked for quite some time but no longer.
> > 
> > Until at least kernel 3.12 I could do:
> > 
> > // export gpio pin
> > // set direction to in
> > // set direction to rising
> > int fd = open("/sys.../value", O_RDONLY);
> > fdset[0].fd = fd;
> > fdset[0].events = POLLPRI;
> > fdset[0].revents = 0;
> > poll(fdset, 1, -1);
> > // at this point pin went high
> 
> Try using lseek before reading the data after the poll.
> 
> EX.
> 	if (fdset[0].revents & POLLPRI) {
> 		lseek(fdset[0].fd, 0, SEEK_SET);
> 		len = read(fdset[0].fd, buf, MAX_BUF);
> 		.
> 		.
> 	}
> 
> See if this helps.

Yes, that fixed it!
Great! Thanks!


Folkert van Heusden

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