Re: [PATCH] Handle reg-shift property for of_serial ports

[David Woodhouse <dwmw2@infradead.org>]

On Sat, 2007-07-07 at 14:10 +0200, Arnd Bergmann wrote:
> On Saturday 07 July 2007, David Woodhouse wrote:
> > 
> > The MV64660 has reg-shift==2 for its otherwise 16550-compatible uarts.
> > While the bootwrapper copes with this, of_serial.c doesn't. (The udbg
> > code doesn't either, but I'll fix that later).
> > 
> > Signed-off-by: David Woodhouse <dwmw2@infradead.org>
> 
> Acked-by: Arnd Bergmann <arnd@arndb.de>
> 
> Given the existence of the boards, it looks correct to do this.
> However, I wonder if it was correct for the MV64660 to claim
> compatibily witn ns16550 if the programming model is not exactly
> the same. The official OF serial port bindings don't mention the
> reg-shift property, so it maybe would have been better to have
> a different value for the "compatible" property, in order not
> to confuse existing operating systems that implement the standard.

Well, so far this only exists in the hacked-up device tree for my
bootwrapper; not in any real firmware. If a reg-shift property is the
wrong way to do it, we can change it. I got the reg-shift thing from
Mark's code in arch/powerpc/boot/ns16550.c, which handles it that way
for the bootwrapper (although I don't see any device-tree blobs which
use it, apart from mine).

-- 
dwmw2