Re: Simple UART driver help and TTY questions

[Jiri Slaby]

On 08/05/2008 06:33 PM, Ira Snyder wrote:
> Hello LKML,
> So, the problem I have is that when I install this driver, it seems to
> return -EIO before it even hits any of the driver code. I checked this
> by putting a printk at the beginning of every function call in the
> module.
>
> The error from busybox microcom is this:
> microcom: can't tcsetattr for /dev/ttytiny0: Input/output error
>
> And cat /dev/ttytiny0:
> cat: /dev/ttytiny0: Input/output error
>
> Previously to finding this code from LinuxJournal, I had tried to write
> my own skeleton driver, basing it on the drivers/serial/ucc_uart.c code.
> It has the exact same problem. I've attached it as well.
>
> So, to the best of my research, it seems like the tcsetattr call would
> come in at drivers/char/tty_ioctl.c in tty_mode_ioctl() (the TCSETS
> case). Maybe I'm wrong, though.
>
> I've built it against both ubuntu's stock kernel (2.6.24 based) and a
> recent pull of the kernel.org kernel.
>
> I'd really appreciate help figuring out what this problem is.

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