On 9/1/2011 9:27 AM, Kumar Gala wrote:

On Aug 25, 2011, at 7:19 AM, Laurentiu Tudor wrote:

Clearing the other TCR bits might break code that sets them (e.g. to setup
the watchdog or fixed interval timer) before start_cpu_decrementer() gets
called.

Can you be more specific about the case you're concerned about.  I'm not sure 
we want to leave the FIT enabled if it was previously.  Watchdog I could 
possibly see leaving alone.

My particular case was this: I was experimenting with having the watchdog enabled during the boot process, in case something goes wrong before the normal watchdog mechanism kicks in. That didn't work without making this modification. Then, thinking that having a function start_cpu_decrementer() touching the other timers and not only the decrementer as its name implies might not be good. So I submitted this patch to the public mailing list to let the community decide if it's useful.

Signed-off-by: Laurentiu Tudor<laurentiu.tu...@freescale.com>
---
arch/powerpc/kernel/time.c |    2 +-
1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index 03b29a6..e8b5cdc 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -721,7 +721,7 @@ void start_cpu_decrementer(void)
        mtspr(SPRN_TSR, TSR_ENW | TSR_WIS | TSR_DIS | TSR_FIS);

        /* Enable decrementer interrupt */
-       mtspr(SPRN_TCR, TCR_DIE);
+       mtspr(SPRN_TCR, mfspr(SPRN_TCR) | TCR_DIE);
#endif /* defined(CONFIG_BOOKE) || defined(CONFIG_40x) */
}

--
1.7.1


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