uplcom / ucom problems on RELENG_5

Bernd Walter ticso at cicely12.cicely.de
Wed Mar 30 02:42:07 PST 2005


On Tue, Mar 29, 2005 at 10:57:23PM -0500, Mike Tancsa wrote:
> 
> I have been trying out USB serial devices on RELENG_5 to see if they are a 
> workable replacement to PCI cards.  Unfortunately, it seems fairly easy to 
> hang such a device. (full dmesg below)
> 
> I have a 28.8 modem connected to a ucom device
> 
> Controller /dev/usb0:
> addr 1: full speed, self powered, config 1, UHCI root hub(0x0000), 
> Intel(0x0000), rev 1.00
>  port 1 addr 2: full speed, power 100 mA, config 1, PL2303 Serial adapter 
> (ATEN/IOGEAR UC232A)(0x2303), Prolific Technology(0x067b), rev 2.02
>  port 2 powered
> 
> 
> I start up a ppp session using it with the speed set to 57600.  I then 
> start up a ping -s 512 pinging something on the other side.  I then kill 
> the connection from the terminal server side to simulate a dialup modem 
> failure.  The pings build up to the point where I get "no buffer space 
> available" and then a few dozen
> 
> putc to a clist with no reserved cblocks
> putc to a clist with no reserved cblocks
> putc to a clist with no reserved cblocks
> putc to a clist with no reserved cblocks
> putc to a clist with no reserved cblocks
> putc to a clist with no reserved cblocks
> putc to a clist with no reserved cblocks
> 
> fill up the console.  At this point, ppp is totally hung, and I cannot kill 
> ppp

You need a way to notice a connection failure.
In case of modem or line failure you should see DCD loss.
Does your cabling release DCD, or do you use LQR in your configuration?
Have you compared the same configuration with a classical 16550 based
serial?

-- 
B.Walter                   BWCT                http://www.bwct.de
bernd at bwct.de                                  info at bwct.de



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