Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

From: Segher Boessenkool
Date: Sat May 19 2007 - 08:28:26 EST


Unfortunately, FIT exists only on Book E CPUs and MPC74xx aren't Book E, IIUC.

By the name "FIT" perhaps, but MPC74xx has essentially
the same thing.

Set MMCR0[TBEE], set MMCR0[PMXE], and choose a TBL bit via MMCR0[TBSEL].

That's the performance monitor, which could very well be
in use already (for performance monitoring stuff, who
would have guessed).

It's also possible to trigger on the CPU cycle counter, but this would
cost one of the performance counters. MPC7400 has 4, later CPUs have 6
or more, and I think xPC7x0 had only 2.

7xx has at least four as well.


Segher

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