Bug#346161: linux-source-2.6.15: serial card (fourport) stopped working
On Sat, 7 Jan 2006 11:55:25 +0100
maximilian attems <maks@sternwelten.at> wrote:
> On Fri, 06 Jan 2006, Andreas Degert wrote:
>
> > I have a fourport serial card, it is correctly detected and
> > configured with the kernel from package
> > linux-image-2.6.12-1-686-smp. The detected ports are ttyS4 - ttyS7
> > (ttyS0/1 is standard serial ports, ttyS2/3 not assigned).
> >
> > With 2.6.15 it works if the (max) number of serial ports is changed
> > from 4 to 8 in the kernel configuration:
> >
> > CONFIG_SERIAL_8250_NR_UARTS=8
> >
> > I don't know if this change in behaviour was intended (2.6.12 works
> > with my card when this parameter set to it's default value of 4,
> > 2.6.14 and 2.6.15 don't).
> >
>
> please add dmesg output to your bugreport.
After looking at the system again, I found that
- only ttyS0 and ttyS1 are detected by the driver
- ttyS4 - ttyS7 are set with setserial in a boot script (which works
for Debian kernel 2.6.12, but not Debian kernel 2.6.15)
Some more search in the Internet revealed:
If you look at the changes for drivers/serial/Kconfig between 2.6.12
and 2.6.13 (e.g.
http://www.linuxhq.com/kernel/v2.6/13/drivers/serial/Kconfig) you'll
find the following part
-----------------------------------------------------------------
config SERIAL_8250_NR_UARTS
- int "Maximum number of non-legacy 8250/16550 serial ports"
+ int "Maximum number of 8250/16550 serial ports"
depends on SERIAL_8250
default "4"
- ---help---
- Set this to the number of non-legacy serial ports you want
- the driver to support. This includes any ports discovered
- via ACPI or PCI enumeration and any ports that may be added
- at run-time via hot-plug.
+ help
+ Set this to the number of serial ports you want the driver
+ to support. This includes any ports discovered via ACPI or
+ PCI enumeration and any ports that may be added at run-time
+ via hot-plug, or any ISA multi-port serial cards.
-----------------------------------------------------------------
This means SERIAL_8250_NR_UARTS (slightly) changed its meaning, starting
with linux 2.6.13. To get the old behaviour, the number should be
increased by the number of legacy serial ports (which I think is 4 for
PC's, COM1 to COM4 in DOS-speak).
I don't think it makes much sense to set
config SERIAL_8250_MANY_PORTS
bool "Support more than 4 legacy serial ports"
to "y" (which the Debian configuration does) and at the same time
set the maximum number of serial ports to 4.
>
> nevertheless this looks like an upstream bug,
> please report it on bugzilla.kernel.org
I'm not so sure it's a bug, because if you have 4 additional serial
ports on your system, according to the Kconfig
documentation .._NR_UARTS has to be increased.
> please inform us of any outcome. :)
> thanks for your report.
thanks for your fast response!
> --
> maks
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