Re: serial port problem with 2.1.132-2.2.0pre5
Sang Kang (kernel@mocha.sarang.net)
Sat, 9 Jan 1999 14:14:47 -0800
On Fri, Jan 08, 1999 at 11:46:42PM -0500, Theodore Y. Ts'o wrote:
> Date: Thu, 7 Jan 1999 04:09:29 -0800
> From: Sang Kang <kernel@mocha.sarang.net>
>
> The issue is that, when I first issued that command (at+...?) using
> the mouse's middle button, not all characters were copiled to the serial
> port but rather forgotten some characters, only displaying "at+".
> when I typed the entire AT command, it worked fine, but when the input
> is too fast it seems to loose the characters.
> Changing the baud rate lower didn't help.
>
> This one's easy. You have one of the buggy uart's which failed to
> deal with the new IRQ autodetection (which changed as part of code
> simplification and an attempt to deal with other buggy uarts....)
>
> Check with setserial; you probably have an rc.serial file which is
> trying to do IRQ autodetection, and the autodetection is failing,
> leaving your IRQ for the port set to zero. Hmm... perhaps I should
> patch the serial driver to set the irq back to its original value if the
> autodetect fails, since that's more likely to work.
>
> The right answer is to hard code the IRQ in your rc.serial script, and
> simply declare the irq to be a specific value. Unfortunately, IRQ
> detection on the ISA bus is devilishly hard to do right, and it can be
> failing for any number of reasons. It doesn't help that 100 different
> manufacturers have tried to do clones of the National Semiconductor
> UART, but many of them don't do competent jobs. So writing generic code
> which works for all of them is not particalarly easy.
>
> - Ted
Ahh... You are right afterall. i used 16550 instead of 16550A for UART.
Thanks,
Sang Kang
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