Re: Handshaking on USB serial devices

From: Greg KH
Date: Thu Feb 21 2008 - 15:59:02 EST


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
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