[PATCH] arch/powerpc/lib/copy_32.S: Use alternate memcpy for MPC512x and MPC52xx

Segher Boessenkool segher at kernel.crashing.org
Fri Jul 9 22:59:09 EST 2010

>>> Actually, this is something which might need closer attention -
>>> and maybe some support in the device tree indicating which read or
>>> write width a device can accept?
>> There already is "device-width"; the drivers never should use any
>> other access width unless they *know* that will work.
> Wouldn't you want to use "bank-width" instead?

We were talking about single devices.  But, sure, when you have
multiple devices in parallel the driver needs to know about that.

> It would be nice to have a device tree property that can specify that
> all access widths supported by the CPU will work, though.

Oh please no.  A device binding should not depend on what CPU there
is in the system.  There could be multiple CPUs of different
architectures, even.

To figure out how to access a device, the driver looks at the device's
node, and all its parent nodes (or asks generic code to do that, or
platform code).


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