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  • Shreyas B. Prabhu's avatar
    powernv/cpuidle: Redesign idle states management · 7cba160a
    Shreyas B. Prabhu authored
    
    
    Deep idle states like sleep and winkle are per core idle states. A core
    enters these states only when all the threads enter either the
    particular idle state or a deeper one. There are tasks like fastsleep
    hardware bug workaround and hypervisor core state save which have to be
    done only by the last thread of the core entering deep idle state and
    similarly tasks like timebase resync, hypervisor core register restore
    that have to be done only by the first thread waking up from these
    state.
    
    The current idle state management does not have a way to distinguish the
    first/last thread of the core waking/entering idle states. Tasks like
    timebase resync are done for all the threads. This is not only is
    suboptimal, but can cause functionality issues when subcores and kvm is
    involved.
    
    This patch adds the necessary infrastructure to track idle states of
    threads in a per-core structure. It uses this info to perform tasks like
    fastsleep workaround and timebase resync only once per core.
    
    Signed-off-by: default avatarShreyas B. Prabhu <shreyas@linux.vnet.ibm.com>
    Originally-by: default avatarPreeti U. Murthy <preeti@linux.vnet.ibm.com>
    Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
    Cc: Paul Mackerras <paulus@samba.org>
    Cc: Michael Ellerman <mpe@ellerman.id.au>
    Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
    Cc: linux-pm@vger.kernel.org
    Cc: linuxppc-dev@lists.ozlabs.org
    Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
    7cba160a