On Sun, Oct 12, 2008 at 3:16 AM, Roman Yeryomin leroi.lists@gmail.com wrote:
On Sat, Oct 11, 2008 at 8:33 PM, ron minnich rminnich@gmail.com wrote:
while trying to resolve this problem I've noticed following:
on system with native bios (tinybios): cat /proc/tty/driver/serial serinfo:1.0 driver revision: 0: uart:16550A port:000003F8 irq:4 tx:945 rx:15 RTS|CTS|DTR|DSR|CD 1: uart:16550A port:000002F8 irq:3 tx:0 rx:0 CTS|DSR|CD
but on system with coreboot: cat /proc/tty/driver/serial serinfo:1.0 driver revision: 0: uart:NS16550A port:000003F8 irq:4 tx:0 rx:0 RTS|DTR 1: uart:unknown port:000002F8 irq:3
OK, this is kind of the problem I remember. If you have time go into the kernel, IIRC, there is a test for some modem signal and the device is not available otherwise. I am sorry to be so fuzzy but this was seven years ago. It was a weird problem.
you think this is kernel problem?
It seems whatever you have on that port is not asserting DTR, which is also odd. Is there a loopback control in this part that routes DSR back to DTR?
Well, according to datasheet there is loopback control in cs5536 uart, but I don't think the problem is there. I've asked Pascal Dornier (pcengines) how he sets up uart in his bios but didn't receive an answer yet. I still think the problem is in coreboot (or libpayload)...
Pascal answered me:
After init -> changes to Linux driver, or does it still use Int 10 + Int 16 ? My BIOS does a redirect of these BIOS interrupts to the serial console.
Roman