Re: serial8250_init and platform_device

Russell King
2005-01-20T19:38:54Z

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