Re: Bug in 8520.c - port.type not set for serial console

Jim Ramsay
2005-06-06T15:04:07Z

On 5/31/05, Bjorn Helgaas <bjorn.helgaas@hp.com> wrote:
> On Monday 30 May 2005 4:38 pm, Jim Ramsay wrote:
> > I am attempting to get the 8520.c driver's serial console working with
> > a 16550A UART implementation, and have run into what I consider to be
> > a bug: In short, the proper 'port.type' for this serial port is not
> > set until the module init (serial8250_init) is called, so the FCR is
> > set incorrectly during serial8250_console_init for any port type which
> > is different than UNKNOWN.
> >
> > The exact problem is that the FCR is being set to '0x0' for a port
> > type of 'UNKNOWN', when for my specific 16550A, it should be set to
> > '0xC1' - and this makes my screen fill with empty characters instead
> > of the printk output I need.
>
> Shouldn't a 16550A UART work correctly with FCR==0x0, i.e., with FIFOs
> disabled? Is your UART broken?

That's a good question. I'll me looking into this in the near future.

> Serial console output is always polled, one character at a time, so
> you shouldn't need FIFOs until later.

True, as long as it works that way... so far I haven't seen it
actually function properly yet with FCR set to 0.

--
Jim Ramsay
"Me fail English? That's unpossible!"