Re: Handshaking on USB serial devices

[Greg KH <greg@kroah.com>]

On Fri, Feb 22, 2008 at 06:05:09AM +1030, David Newall wrote:
> Alan Cox wrote:
> >> developing is entirely wrong.  Oh well.  Mind you, providing a
> >> write_room function is NOT a real solution; it merely reduces the
> >> condition to a usually-winnable race.  (Ironically, when I back-ported
> >> the 2.6 driver, I excluded its new write_room function.  Mistake.)
> >>     
> >
> > What race do you see left ?
> >   
> 
> On second thoughts I'm not sure that I do.  I've had my head so full of
> 2.4 pl2303, and 2.4 pl2303 with this, that and the other added to it,
> that I was probably just confused.  Certainly it's not important,
> because I didn't mean the 2.6 driver, but an hypothetical 2.4 with a
> simplistic write_room function added (e.g. return
> port->write_urb->status == -EINPROGRESS ? 0 : 64).  OPOST processing's
> use of putchar to expand CRLF sends two writes (or putchars), with no
> intervening checks.  Since I'm just polishing off my back-port of
> 2.6.24.1 pl2303 to kernel 2.4, the matter is quite irrelevant.
> 
> By the way, what happened to HUawei E620 UMTS/HSDPA card?  It's in
> pl2303 in 2.6.23; not in 2.6.24.1.  (Do I remove it from my back-port?)

Yes, please remove it, it was incorrectly listed in the pl2303 driver in
the .23 kernel.

thanks,

greg k-h