On 09/03/2015 13:35, Peter Hurley wrote:
On 03/09/2015 07:27 AM, Måns Rullgård wrote:
Mason <slash.tmp@xxxxxxx> writes:
On 09/03/2015 10:34, Mason wrote:
On a tangential subject, as Mans stated, Au1x00 does not support
the scratch register; but Ralink and Tango do. These three
platforms share the weird register layout (requiring the LUTs),
but they differ in scratch support.
Would it make any sense to differentiate them, to support scratch
where it is implemented? (Although adding offset 7 to au_io_out_map
would then make that table sparse!)
A related issue in 8250_early.c
probe_baud() and init_port() are using serial8250_early_in() and
serial8250_early_out() to read/write the UART registers.
unsigned int __weak __init serial8250_early_in(struct uart_port *port, int offset)
{
switch (port->iotype) {
case UPIO_MEM:
return readb(port->membase + offset);
case UPIO_MEM32:
return readl(port->membase + (offset << 2));
case UPIO_PORT:
return inb(port->iobase + offset);
default:
return 0;
}
}
These are __weak but I didn't find any overriding implementation.
In the UPIO_AU case, I think they are NOPs(?) so how can they work
correctly on Ralink/Tango platforms? (Confused)
It doesn't work correctly.
What is 8250_early.c used for?
As the name implies, it implements an early console that can be used
before the whole tty/console system has been brought up. Apparently
nobody bothered adding support for UPIO_AU there.
If there's interest in having earlycon support on this platform,
I can add that pretty easily on top of the same patchset in which
I added Beaglebone Black earlycon.
When is the cutoff between early console / regular console?
As far as I understand (which is possibly wrong) the way the code is
currently written in the Tango3 port, early support works. But it boils
down to a shameless sprinkling of ifdefs and hard-coded offsets.
Maybe I don't need early console, I'll have to take a closer look.
Regards.
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