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    SubjectRe: [GIT PULL] omap changes for v2.6.39 merge window
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    On Mon, 2011-04-04 at 22:08 +0200, Linus Walleij wrote:
    > 2011/4/4 Marc Zyngier <Marc.Zyngier@arm.com>:
    > > On Mon, 2011-04-04 at 14:31 +0100, Russell King - ARM Linux wrote:
    > >>
    > >> If ARM are going to architect a set of timers into the hardware, let's
    > >> make sure that all such hardware has them so we can dig ourselves out
    > >> of this crappy mess that we find ourselves in today.
    > >
    > > As far as I know, A15 always has a set of generic timers.
    > >
    > > It may be that they are not available (frequency not programmed into the
    > > CNTFREQ register), or that someone decided to use a better alternative
    > > (for some particular interpretation of "better").
    >
    > I guess this thing is inside that A15 core?
    >
    > First, what happens the day any vendors start making SoCs on this is
    > they turn the A15 core off whenever it is not used, loosing all state
    > including this timer, I believe.

    The main counter is located in an ALWAYS_ON power domain, and should
    keep going whatever happens in the system.

    [...]

    > Second, have you taken into account the effect of changing the
    > frequency of the A15 core, which is something every vendor also
    > does, as you know Colin Cross already has a patch pending
    > for that on the TWD localtimer which has not yet reached
    > the kernel. (Or is A15 fixed frequency? Forgive my ignorance...)

    Fixed frequency, with a minimal roll-over time of 40 years.

    M.
    --
    Reality is an implementation detail.




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