Re: [PATCH] Exar quad port serial

Paul B Schroeder
2006-10-18T15:07:29Z

Lennart Sorensen wrote:
> On Tue, Oct 17, 2006 at 08:00:17PM -0500, Paul B Schroeder wrote:
>> Sorry for the late response.. Here is a fuller explanation. Maybe
>> somebody out there has a better solution:
>>
>> This is on our "Envoy" boxes which we have, according to the documentation,
>> an "Exar ST16C554/554D Quad UART with 16-byte Fifo's". The box also has
>> two other "on-board" serial ports and a modem chip.
>>
>> The two on-board serial UARTs were being detected along with the first two
>> Exar UARTs. The last two Exar UARTs were not showing up and neither was
>> the modem.
>>
>> This patch was the only way I could the kernel to see beyond the standard
>> four serial ports and get all four of the Exar UARTs to show up.
>>
>> I hope this explains it well enough..
>
> I suspect all you have to do might be to change how many ports it looks
> for. The default max ports is 4 I believe on many kernel versions.
>
> Look for CONFIG_SERIAL_8250_NR_UARTS and
> CONFIG_SERIAL_8250_RUNTIME_UARTS in the kernel config.
>
Yea.. I tried that.. It had no effect..

> If that doesn't work and you do need a special driver, at least label it
> with more detail like 'for exar st16c554 quad uart' or 'for envoy board'
> or whatever makes it clear which hardware it is for. I use exar pci
> uarts (exar XR17d15[248] chips) which work fine already with the 8250
> driver, or optionally with the jsm driver with a small change to the
> list if pci identifiers. THey of course would not work with your driver
> since they are completely different exar chips (even though one is also
> a quad uart, although 64byte fifo).
In that case, I will redo the patch with better labeling..

Thanks...Paul...

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Paul B Schroeder <pschroeder "at" uplogix "dot" com>
Senior Software Engineer
Uplogix, Inc. (http://www.uplogix.com/)