Re: serial8250_init and platform_device

[Russell King <rmk+lkml@arm.linux.org.uk>]

On Thu, Jan 20, 2005 at 01:06:55PM -0600, Kumar Gala wrote:
> Russell,
> 
> I think this all makes sense to me.  I'm just wondering why we would 
> have a platform device register in a system for 'legacy ISA' when we 
> know the system doesnt have any ports that will fit the category.
> 
> As you show in example #2 you have
> 
> .../devices/platform/serial82500
> .../devices/platform/serial8250
> 
> why have the 'serial8250' if you know your system doesnt have any ports 
> that will exist there?

In this case, it is a placeholder, and needs to be there if you're using
power management.

For instance, you may use setserial on /dev/ttyS2 to reconfigure it
to an address where you know a serial port is.  Without the "serial8250"
device, it isn't linked into the device model, and therefore doesn't
receive any power management notifications.

Once the SERIAL_PORT_DFNS are gone, and we have a more modern interface
than setserial for setting up random ports, this "serial8250" device
will vanish.

While we're here, you've reminded me about an annoying point about
platform device naming...

Greg - the name is constructed from "name" + "id num" thusly:

	serial8250
	serial82500
	serial82501
	serial82502

When "name" ends in a number, it gets rather confusing.  Can we have
an optional delimiter in there when we append the ID number, maybe
something like a '.' or ':' ?

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:  2.6 PCMCIA      - http://pcmcia.arm.linux.org.uk/
                 2.6 Serial core