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    Subject[PATCH 2/6] PM / Domains: Fix hibernation restore of devices
    Date
    From: Rafael J. Wysocki <rjw@sisk.pl>

    During resume from hibernation pm_genpd_restore_noirq() has to
    deal with software state left by pm_genpd_suspend_noirq() and
    unknown hardware state (the boot kernel may leave all PM domains and
    devices in arbitrary states). For this reason, make it attempt to
    power cycle each domain when before resuming its first device to
    possibly get rid of any unwanted hardware state that may interfere
    with genpd_start_dev() later on.

    Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
    ---
    drivers/base/power/domain.c | 21 +++++++++++++--------
    1 file changed, 13 insertions(+), 8 deletions(-)

    Index: linux/drivers/base/power/domain.c
    ===================================================================
    --- linux.orig/drivers/base/power/domain.c
    +++ linux/drivers/base/power/domain.c
    @@ -770,8 +770,10 @@ static int pm_genpd_prepare(struct devic

    genpd_acquire_lock(genpd);

    - if (genpd->prepared_count++ == 0)
    + if (genpd->prepared_count++ == 0) {
    + genpd->suspended_count = 0;
    genpd->suspend_power_off = genpd->status == GPD_STATE_POWER_OFF;
    + }

    genpd_release_lock(genpd);

    @@ -1103,20 +1105,24 @@ static int pm_genpd_restore_noirq(struct
    * Since all of the "noirq" callbacks are executed sequentially, it is
    * guaranteed that this function will never run twice in parallel for
    * the same PM domain, so it is not necessary to use locking here.
    + *
    + * At this point suspended_count == 0 means this routing is being run
    + * for the first time for the given domain in the present cycle.
    */
    - genpd->status = GPD_STATE_POWER_OFF;
    - if (genpd->suspend_power_off) {
    + if (genpd->suspended_count++ == 0) {
    /*
    - * The boot kernel might put the domain into the power on state,
    - * so make sure it really is powered off.
    + * The boot kernel might put the domain into arbitrary state,
    + * so make sure it is powered off.
    */
    + genpd->status = GPD_STATE_POWER_OFF;
    if (genpd->power_off)
    genpd->power_off(genpd);
    - return 0;
    }

    + if (genpd->suspend_power_off)
    + return 0;
    +
    pm_genpd_poweron(genpd);
    - genpd->suspended_count--;

    return genpd_start_dev(genpd, dev);
    }
    @@ -1623,7 +1629,6 @@ void pm_genpd_init(struct generic_pm_dom
    genpd->poweroff_task = NULL;
    genpd->resume_count = 0;
    genpd->device_count = 0;
    - genpd->suspended_count = 0;
    genpd->max_off_time_ns = -1;
    genpd->domain.ops.runtime_suspend = pm_genpd_runtime_suspend;
    genpd->domain.ops.runtime_resume = pm_genpd_runtime_resume;


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