Re: [PATCH] Enable console on PCI serial devices

[Bjorn Helgaas <bjorn.helgaas@hp.com>]

On Monday 20 October 2008 11:43:51 am n0ano@n0ano.com wrote:
> On Mon, Oct 20, 2008 at 11:11:07AM -0600, Bjorn Helgaas wrote:
> >... 
> > It doesn't bother me that the number is large.  It's only a factor
> > of 16 bigger than the baud rate.  It is sort of magic, but on the
> > other hand, the number is often printed on a part on the board, so
> > it's easy to determine, and fairly easy to document.  If you've
> > lost the box with the marketing messages on it, I'd argue that it's
> > easier to determine the clock rate than the fastest baud rate.
> > 
> > To me it seems more confusing to specify two baud rates: the one
> > you want to use, and the fastest one the UART supports.
> 
> Well, how about consistency with the current serial driver.  The
> current driver uses base baud, as evidenced by this code from
> `drivers/serial/8250_pci.c':
> 
> static struct pciserial_board pci_boards[] __devinitdata = {
>         [pbn_default] = {
>                 .flags          = FL_BASE0,
>                 .num_ports      = 1,
>                 .base_baud      = 115200,
>                 .uart_offset    = 8,
>         },
> 
> I think it's even more important to follow what the driver is
> doing.  (If I'd lost the bix I would get the PCI IDs and see
> what the driver is doing for my unknown card :-)

Ideally we could put something in Documentation/kernel-parameters.txt
that's useful for people who can't or don't want to look at
the source.

Bjorn