Date: Wed, 25 Jun 2003 15:27:30 +0300 From: Danny Braniss <danny@cs.huji.ac.il> To: ticso@cicely.de Cc: freebsd-hackers@freebsd.org Subject: Re: USB, select/poll for ucom Message-ID: <E19V9N4-000CpW-00@cs.huji.ac.il> In-Reply-To: Message from Bernd Walter <ticso@cicely12.cicely.de> <20030625120837.GC52854@cicely12.cicely.de>
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> On Wed, Jun 25, 2003 at 01:13:56PM +0300, Danny Braniss wrote:
> > hi,
> > while trying to port an application that works with tty to uplcom/ucom,
> > (and it doesn't work :-), and looking at the kernel sources and
> > trying to figure out USB, i think that select(2)/poll(2) will not work,
> > correct?
>
> I've seen Problemes with non 8n1 communications and I've also seen
> problems because most USB adapters only deliver 5.5V to the lines.
> I never noticed any select/poll problems and I don't think we have any
> because this is handled in common code at tty level.
>
> If you have any condition that shows something different please let
> us know.
>
i turned debug on and i could not see any calls to ucomread,
the program calls select(...) - but select does not initiate anything,
it justs waits to be woken when something is received (in the case of reading),
now, unless im wrong - which well could be :-), the read in this case must be
started - usb is a master/slave protocol, and this is not happening.
if(select(fdset,...)) {
if(FD_ISSET(ifd, fdset))
read(ifd, ...
...
}
danny
PS: im using 5.1-current, and im trying to get a Towitoko smartcard reader to
work.
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