On Wednesday 22 January 2014 15:17:49 Mark Rutland wrote:

Except for the fact that some timers / clocksources that we already have
in 32-bit land will likely be reused in 64-bit SoC designs. People will
want to use the same driver for both 32-bit and 64-bit kernels, and thus
we need CLOCKSOURCE_OF_DECLARE in 64-bit kernels.

Those platforms which will have ACPI will likely reuse existing timer IP
blocks, and will want to make minimal changes to the driver, which will
likely be using CLOCKSOURCE_OF_DECLARE. We can't change these to
platform drivers or we can break existing systems because the timers
will be registered too late.

I don't see how we can share drivers between 32-bit and 64-bit kernels
without sharing a common driver model, and I think it makes sense to
have some uniformity across drivers (i.e. always use
CLOCKSOURCE_*_DECLARE rather than sometimes using platform drivers).

This still sounds like speculation. I would defer this change until
we actually have a platform that needs it.

The platforms that would reuse a lot of IP blocks are most likely
embedded systems and /not/ server hardware following some strict
specification, so they wouldn't use ACPI.

	Arnd