On Wednesday 04 August 2004 03:37pm, Gene Wang wrote:
> Hi,
> I am trying to use usb_serail_converter+crossover serial cable+
> serail_usb_converter to connect two Linux PCs using PPP. I am using
> pl2303.o and usbserial.o drivers. I can set the baud rate to be 460800
> and my PPP link can work at this baud. But if I set the baud rate to be
> higher than that like 921600, my ppp link only gives me the same
> performance as baud rate 230400 which means the actual baud rate can not
> be set to 921600. Therefore, my question is, can pl2303.o and
> usbserial.o support baud rate higher than 460800? (I am using Linux
> 2.4.19)
Gene,
Since nobody responded to you yet, I figured I'd take a look at this issue
since I have an IOGear GUC232A USB/RS-232 adapter (which uses the 'pl2303'
driver).
A quick look at the code ('pl2303.c') for the 2.4.26 kernel shows that the
driver doesn't support anything higher than 460800 bps. I doubt that the
2.6.x kernels have anything better either but I don't have any 2.6.x source
handy ATM.
Nevertheless, my documentation for my IOGear GUC232A implies that it can
support rates of around 1M bps, so it may be a matter of just adding a few
lines of code to 'pl2303.c' and recompiling your kernel modules to allow use
of higher rates:
B500000, B576000, B921600, B1000000, B1152000
Those last 2 may be pushing the limit a bit, but you could always try it.
I intended to do just that, so I set up a null-modem cable between 2 PCs, with
the USB/RS-232 adapter on the "server" PC. Unfortunately, every time I shut
down 'pppd' on the "client" PC, 'pppd' on the server PC would crash/hang
horribly, but only when using the USB/RS-232 adapter. It quickly became a
major pain in the neck to test anything, even before I had applied a patch to
'pl2303.c' for higher bps rates. Maybe some time in the future I'll have more
time to set up a test machine and try this all again.
Until then, if you're comfortable altering 'pl2303.c' and recompiling your
kernel modules, I'd say you should give it a shot.
Sorry I can't be of more help here....
Bill Marr
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