Re: R: How to avoid serial port buffer overruns?

From: Lee Revell
Date: Fri Aug 18 2006 - 12:56:49 EST

On Fri, 2006-08-18 at 10:48 +0200, Giampaolo Tomassoni wrote:
> > On Thu, 2006-08-17 at 00:19 +0100, Russell King wrote:
> >
> >
> > OK, thanks. FWIW here is the serial board we are using:
> >
> >
> >
> > The hardware guy says "The mn9845cv, have in default 2 serial ports and
> > one ISA bus, where we have connected the tl16c554, quad serial port."
> >
> > Hopefully Ingo's latency tracer can tell me what is holding off
> > interrupts.
> I beg your pardon: I'm not used that much to interrupts handling in Linux, but this piece of code from sound/drivers/serial-u16550.c in a linux-2.6.16:

OK, they are not using serial-u16550 but 8250_fourport for some reason:

# cat /proc/tty/driver/serial
serinfo:1.0 driver revision:
0: uart:16550A port:000003F8 irq:4 tx:0 rx:0
1: uart:unknown port:000002B8 irq:5
2: uart:unknown port:000003E8 irq:4
3: uart:unknown port:000002E8 irq:3
4: uart:16550A port:0000DD00 irq:185 tx:234335 rx:47502 RTS|DTR
5: uart:16550A port:0000E300 irq:185 tx:249926 rx:27732 RTS|DTR
6: uart:16550A port:0000E400 irq:185 tx:120958 rx:0 RTS|DTR
7: uart:16550A port:0000D000 irq:185 tx:0 rx:0
8: uart:16550A port:0000D100 irq:185 tx:0 rx:0 RTS|DTR
9: uart:16550A port:0000D200 irq:185 tx:0 rx:123406 RTS|DTR

It looks like no overruns are reported, but I have to find out whether
they have reproduced the bug since the last reboot.

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