Caching in the MPC107, linux 2.6
adrian at humboldt.co.uk
Tue Mar 16 09:42:13 EST 2004
On Mon, 2004-03-15 at 20:38, Tom Rini wrote:
> Actually, I was thinking that having an extra nop there on the !SMP &&
> !(745x && MPC107) case wouldn't hurt much / at all, and having this
> feature bit be done unconditionally. But in cpu_setup_6xx.S we would
> compare the host bridge vendor / device ID to that of an mpc107. Or am
> I not thinking right, and doing that comparison at that time would be a
> bad idea? If so, I can live with it being an unconditional option, iff
> it's only required when MPC10X_STORE_GATHERING is enabled.
The only problem I see is that in cpu_setup_6xx.S we can't yet do the
config cycles to tell that it is an MPC107. Luckily, all MPC10x boards
that I know of require an explicit platform selection option.
I made my patch depend on CONFIG_MPC10X_BRIDGE, instead of
CONFIG_MPC10X_STORE_GATHERING, because I'm in the middle of porting
other MPC107 drivers from kernel 2.4 to 2.6.
An extra nop won't hurt, but there is a performance cost to
_PAGE_COHERENT which we should avoid unless necessary.
- Adrian Cox
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