Messages in this thread | | | Date | Fri, 23 Jan 2009 19:05:17 +0000 | From | Andrew Walrond <> | Subject | Re: serial8250 madness |
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Alan Cox wrote: >> ttyS0 works fine. Can get grub output, kernel boot and console via ttyS0 >> as I wanted. >> ttyS1 doesn't work at all. It's detected, enabled in the bios etc etc >> but just doesn't work at all. >> > > You don't give much information but if it seems to be non working then I > would look hard at the IRQ/IO reported > > On Machine A (ttyS0 works fine. ttyS1 dead as dodo): $ dmesg | grep ttyS
Command line: console=tty0 console=ttyS0,57600 Kernel command line: console=tty0 console=ttyS0,57600 console [ttyS0] enabled serial8250: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A serial8250: ttyS1 at I/O 0x2f8 (irq = 3) is a 16550A 00:05: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A 00:06: ttyS1 at I/O 0x2f8 (irq = 3) is a 16550A
$ sudo ./setserial -a /dev/ttyS1
/dev/ttyS1, Line 1, UART: 16550A, Port: 0x02f8, IRQ: 3 Baud_base: 115200, close_delay: 50, divisor: 0 closing_wait: 3000 Flags: spd_normal skip_test
user@orac ~ $ cat /proc/interrupts CPU0 CPU1 0: 35 20 IO-APIC-edge timer 1: 0 2 IO-APIC-edge i8042 3: 0 1 IO-APIC-edge 4: 0 179 IO-APIC-edge serial [snip]
>> Machine B >> >> ttyS0 and ttyS1 will both receive, but neither will send. Go figure. >> Tested using a null modem cable, setserial and cu against the known good >> machine above. >> > > Boggle - what flow control wiring have you done ? > > :) Same null modem cable as used in all other tests. Setup with setserial then connect either ends with the likes of cu -s 9600 -l /dev/ttyS? and this machine can receive and display characters typed on the other end, but nothing gets sent the other way. Have tried with hardware/software flow on/off at both ends. Clueless...
I havent tried yet but will see if grub will push anything out (ie independent of the kernel) which will rule out a hardware problem and implicate the kernel. But its a relatively new m/b with onboard serial so I doubt it's broken. Will report back. > > The big outstanding bug I know about is the incompatibility between the > PnP 8250 drivers and serial console - that may be your machine C case. > That one is rather hard to fix so on the long rather than short term hit > list. > Sounds likely. Any way I can know for sure? The kernel log looks a bit different on this machine:
Serial: 8250/16550 driver4 ports, IRQ sharing disabled serial8250: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A serial8250: ttyS1 at I/O 0x2f8 (irq = 3) is a 16550A serial 00:09: activated 00:09: ttyS2 at I/O 0x3e8 (irq = 3) is a 16550A serial 00:0a: activated 00:0a: ttyS3 at I/O 0x2e8 (irq = 5) is a 16550A
compared with Machine A:
Serial: 8250/16550 driver4 ports, IRQ sharing enabled serial8250: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A serial8250: ttyS1 at I/O 0x2f8 (irq = 3) is a 16550A 00:05: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A 00:06: ttyS1 at I/O 0x2f8 (irq = 3) is a 16550A
Thanks for your input
Andrew Walrond > Alan > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > >
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