Re: Handshaking on USB serial devices

[David Newall <davidn@davidnewall.com>]

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?)