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    SubjectRe: [v4 PATCH 1/5]: cpuidle: Cleanup drivers/cpuidle/cpuidle.c
    * Peter Zijlstra <a.p.zijlstra@chello.nl> [2009-09-02 07:42:24]:

    > On Tue, 2009-09-01 at 17:08 +0530, Arun R Bharadwaj wrote:
    > > * Arun R Bharadwaj <arun@linux.vnet.ibm.com> [2009-09-01 17:07:04]:
    > >
    > > Cleanup drivers/cpuidle/cpuidle.c
    > >
    > > Cpuidle maintains a pm_idle_old void pointer because, currently in x86
    > > there is no clean way of registering and unregistering a idle function.
    >
    > Right, and instead of fixing that, they build this cpuidle crap on top,
    > instead of replacing the current crap with it.
    >
    > > So remove pm_idle_old and leave the responsibility of maintaining the
    > > list of registered idle loops to the architecture specific code. If the
    > > architecture registers cpuidle_idle_call as its idle loop, only then
    > > this loop is called.
    >
    > OK, that's a start I guess. Best would be to replace all of pm_idle with
    > cpuidle, which is what should have been done from the very start.
    >
    > If cpuidle cannot fully replace the pm_idle functionality, then it needs
    > to fix that. But having two layers of idle functions is just silly.
    >
    > Looking at patch 2 and 3, you're making the same mistake on power, after
    > those patches there are multiple ways of registering idle functions, one
    > through some native interface and one through cpuidle, this strikes me
    > as undesirable.
    >
    > If cpuidle is a good idle function manager, then it should be good
    > enough to be the sole one, if its not, then why bother with it at all.
    >

    Okay, I'm giving this approach a shot now. i.e. trying to make cpuidle
    as _the_ sole idle function manager. This would mean doing away with
    pm_idle and ppc_md.power_save. And, cpuidle_idle_call() which is the
    main idle loop of cpuidle, present in drivers/cpuidle/cpuidle.c will
    have to be called from arch specific code of cpu_idle()

    Also this would mean enabling cpuidle for all platforms, even if the
    platform doesn't have multiple idle states. So suppose a platform doesnt
    have multiple states, it wouldn't want the bloated code of cpuidle
    governors, and would want just a simple cpuidle loop.

    --arun
    >


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