Re: DragonFly-2.3.0.876.g136cd master sys/dev/acpica5 acpi_hpet.c

[Joerg Sonnenberger <joerg@xxxxxxxxxxxxxxxxx>]

On Tue, May 05, 2009 at 11:32:35AM +0800, Sepherosa Ziehau wrote:
> On Tue, May 5, 2009 at 10:51 AM, Joerg Sonnenberger
> <joerg@britannica.bec.de> wrote:
> > On Sun, May 03, 2009 at 04:35:04AM -0700, Sepherosa Ziehau wrote:
> >>     hpet: Veto Sx state transition, if hpet is the sys_cputimer, since
> >>     hpet is not required to function under S1-S5.  Add comment about
> >>     the reference to the related hpet standard items.
> >
> > Huh? Why do you block S3 and S4 as well?
> 
> Main counter may not be preserved in S3 and S4; I didn't find a good
> spot on the code path to safely save/restore the main counter, that's
> also why S1 and S2 are vetoed.  Any insight?

Why do you care about the actual counter value? Like for the i8254, it
has to be reprogrammed after S3/S4 or at least recomputed by the code
that reads back the RTC value.

Joerg