# Re: \[PATCH\] powerpc/time: When starting the decrementer don't zero the other bits in TCR

- From: Kumar Gala \<hidden\>
- Date: 2011-09-01 18:49:47 
- List: linuxppc-dev
- Page: https://ratatoskr.run/linuxppc-dev/2011/09/9466197
- Thread: https://ratatoskr.run/linuxppc-dev/2011/08/9466090/t.md

```text

On Sep 1, 2011, at 10:38 AM, Tudor Laurentiu wrote:

> On 9/1/2011 4:56 PM, Kumar Gala wrote:
>>=20
>> On Sep 1, 2011, at 3:31 AM, Tudor Laurentiu wrote:
>>=20
>>> On 9/1/2011 9:27 AM, Kumar Gala wrote:
>>>>=20
>>>> On Aug 25, 2011, at 7:19 AM, Laurentiu Tudor wrote:
>>>>=20
>>>>> 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.
>>>>=20
>>>> 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.
>>>=20
>>> 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.
>>=20
>> So I think renaming the function is fine, and I think not touching =
the watchdog bits is also reasonable.  So if you update the patch along =
those lines I think we can push in.  I do want to make sure that the FIT =
is disabled as we dont expect it.
>=20
> how about:
>=20
> static void setup_cpu_timers()
>=20
> ?

Sounds fine to me

>=20
>> Probably add a comment about how care needs to be taken if the =
wathchdog is enable be firmware or a previous kernel.
>=20
> OK.
>=20
>=20
>=20
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```