• Thomas Petazzoni's avatar
    ARM: mvebu: synchronize secondary CPU clocks on resume · b9b1de0f
    Thomas Petazzoni authored
    The Armada XP has multiple cores clocked by independent clocks. The
    SMP startup code contains a function called set_secondary_cpus_clock()
    called in armada_xp_smp_prepare_cpus() to ensure the clocks of the
    secondary CPUs match the clock of the boot CPU.
    
    With the introduction of suspend/resume, this operation is no longer
    needed when booting the system, but also when existing the suspend to
    RAM state. Therefore this commit reworks a bit the logic: instead of
    configuring the clock of all secondary CPUs in
    armada_xp_smp_prepare_cpus(), we do it on a per-secondary CPU basis in
    armada_xp_boot_secondary(), as this function gets called when existing
    suspend to RAM for each secondary CPU.
    
    Since the function now only takes care of one CPU, we rename it from
    set_secondary_cpus_clock() to set_secondary_cpu_clock(), and it looses
    its __init marker, as it is now used beyond the system initialization.
    
    Note that we can't use smp_processor_id() directly, because when
    exiting from suspend to RAM, the code is apparently executed with
    preemption enabled, so smp_processor_id() is not happy (prints a
    warning). We therefore switch to using get_cpu()/put_cpu(), even
    though we pretty much have the guarantee that the code starting the
    secondary CPUs is going to run on the boot CPU and will not be
    migrated.
    Signed-off-by: default avatarThomas Petazzoni <thomas.petazzoni@free-electrons.com>
    Acked-by: default avatarGregory CLEMENT <gregory.clement@free-electrons.com>
    Link: https://lkml.kernel.org/r/1416585613-2113-14-git-send-email-thomas.petazzoni@free-electrons.comSigned-off-by: default avatarJason Cooper <jason@lakedaemon.net>
    b9b1de0f
platsmp.c 4.54 KB