Am Mittwoch, den 28.06.2017, 08:07 +1000 schrieb Stuart Longland:
Hi,
> >> and to select 4-wire ("full duplex") RS-485, one does:
> >> # echo rs485fd > /sys/class/tty/ttyUSB0/standard
> > This looks like something that people will put into udev.
> > So the switch will be done via udev, but the user not necessarily
> > started via udev. Looks like a race to me.
>
> It is a race, but unless a daemon is watching for the very moment that a
> particular serial interface appears, it's one that init scripts are very
> likely to win.
That is precisely what a demon might do.
> Short of having a flag that blocks reads/writes until a given sysfs file
> is written to say "I'm ready, go ahead"… there aren't that many options
> I can think of.
1) module option
2) ioctl
Regards
Oliver
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