Re: [RFC] clocksouce implementation for powerpc

From: Tony Breeds
Date: Fri Jun 22 2007 - 02:10:58 EST


On Wed, Jun 20, 2007 at 08:53:47PM +0400, Sergei Shtylyov wrote:

Hi Sergei,
Thanks for taking the time to look over my patch.

> I guess it's been based on the prior work by John Stultz (and me too :-)?

At some level I guess so. John did send me a patch a while ago.

> If you mean the init. part, this has been already done by me -- I've
> implemented read_persistent_clock() and got rid of xtime setting. What's
> left is to implemet update_persistent_clock() and get rid of
> timer_check_rtc()...

Actually I think that comment is redundant. and should be removed
sorry.

> Perhaps we even need to raise the rating to 300 or 400 -- according to
> what <linux/clocksource.h> says?

Sure.

> >+ .flags = CLOCK_SOURCE_IS_CONTINUOUS,
> >+ .mask = CLOCKSOURCE_MASK(64),
> >+ .shift = 22,
>
> PPC64 has issues with the fixed shift value, see:
>
> http://patchwork.ozlabs.org/linuxppc/patch?id=11125

Thanks!

> >+ .mult = 0, /* To be filled in */
> >+ .read = NULL, /* To be filled in */
> >+ .settimeofday = NULL, /* To be filled in */
>
> I don't quite understand why not just init them right away? The values
> are fixed anyways.

Well at least mult needs to be calculated at runtime, and I prefer to
have the structure near the top of the file at which stage the
read/settimeofday functions aren't defined.

Yours Tony

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