Re: [PATCH] tty: 8250_dw: fix build error for CONFIG_SERIAL_8250=m

[Jamie Iles <jamie@jamieiles.com>]

On Wed, Aug 24, 2011 at 04:45:16PM +0200, Arnd Bergmann wrote:
> On Wednesday 24 August 2011, Jamie Iles wrote:
> > Allow 8250_dw to be built as a module and export serial8250_handle_irq
> > so that 8250 can still be built as a module.  This prevents the
> > following build failure:
> > 
> > drivers/built-in.o: In function `dw8250_handle_irq':
> > 8250_dw.c:(.text+0xcad9c): undefined reference to `serial8250_handle_irq'
> 
> I think this won't fix the bug that Stephen was reporting, it will only
> make the error message go away but it won't work in the end: When
> CONFIG_SERIAL_8250_DW is set to 'm', the declaration of
> serial8250_use_designware_io now gets stubbed out from of_serial.ko,
> meaning that the 8250_dw module becomes useless.
> 
> At the very least you also need to export the serial8250_use_designware_io
> symbol and check for CONFIG_SERIAL_8250_DW_MODULE in the header.

Ahh, I didn't realise that this would define 
CONFIG_SERIAL_8250_DW_MODULE rather than CONFIG_SERIAL_8250_DW.

> When go go to such length, I think the approach I initially advocated
> (making 8250_dw a standalone platform_driver like of_serial) will be
> nicer.

OK, in hindsight that does seem like a much better option.  I'll spin a 
separate platform_driver instead.

Greg, I'm not sure how to best handle this, do you want patches to 
revert:

	tty: serial8250: add helpers for the DesignWare 8250
	tty: of_serial: add support for the DesignWare 8250

or can these be dropped?

Thanks,

Jamie