Re: [PATCH v3 0/7] mv643xx.c: Add basic device tree support.

On Thursday 09 August 2012, Ian Molton wrote:

quoted

 I think showing one
parent device with children at address 0, 1 and 2 is ok.

Is it acceptable for the child devices to directly access the
parents register space? because there would be no other
way for that to work.

Yes, I see no problem with that. As long as all the drivers
agree on who can access what.

quoted

 The driver
already knows all those offsets and they are always the same
for all variants of mv643xx, right?

Yes, but its not clean. And no amount of refactoring is
really going to make a nice driver that also fits the ancient
(and badly thought out) OF bindings.

In what way is it badly though out, or not clean? The use of
underscores in the properties, and the way that the sram
is configured is problematic, I agree. But The way that
the three ports are addressed and how the PHY is found
seems quite clever.

If we have to break things, we can at least go for a nice
clean design, surely?

The ports arent really child devices of the MAC. The MAC
just has 3 ports.

I don't see the difference between those two things.

Luckily, it looks like the existing users don't actually use
the device tree to set up the driver at all, preferring to
translate their D-T bindings to calls to
platform_device_register() so all we'd need to do to
support them is completely ignore them.

We're going to have to maintain a legacy
platform_device -> DT bindings hack somewhere anyway,
at least until the remaining other users of the driver
convert to D-T.

I don't understand why you describe the method used in
powerpc as a hack. It was the normal way to introduce
DT support for platform devices back when it was implemented.
It also had the advantage of not requiring any modifications
to the generic driver, because it was shared between one
architecture using DT (powerpc) and one that didn't (ARM).

	Arnd