umcs (4-Port-USB-serial) triggering way too much ehci IRQs

Ian Lepore ian at
Tue Sep 17 20:08:39 UTC 2013

On Tue, 2013-09-17 at 23:08 +0400, Lev Serebryakov wrote:
> Hello, Harald.
> You wrote 17 сентября 2013 г., 21:43:17:
> HS> Is that worth a try?
> HS>
>   Nope. I've started from this driver, and it even doesn't support BREAK
>  signal (it is was first reason why I start to write new one -- I needed
>  BREAK to enter kernel debugger).
> HS> At least, it seems to be possible to enable RS485-mode :-) :-)
>   I could easily add RS485 mode, BUT! FreeBSD doesn;'t have any userland API
>  for it, and the same is true for higher and non-standard baud rates.

There's no API needed for higher baud rates.  I've used cfsetspeed() to
set 3mbps on ftdi chips.   I've also used it for completely arbitrary
speeds like 554000bps (happens to be the fastest I can run an ftdi chip
on a 180mhz arm without dropping chars, but going that fast requires
other changes to the driver.).

-- Ian

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