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    Subject[Update][PATCH 3/6] PM / Domains: Introduce "always on" device flag
    Date
    From: Rafael J. Wysocki <rjw@sisk.pl>

    The TMU device on the Mackerel board belongs to the A4R power domain
    and loses power when the domain is turned off. Unfortunately, the
    TMU driver is not prepared to cope with such situations and crashes
    the system when that happens. To work around this problem introduce
    a new helper function, pm_genpd_dev_always_on(), allowing a device
    driver to mark its device as "always on" in case it belongs to a PM
    domain, which will make the generic PM domains core code avoid
    powering off the domain containing the device, both at run time and
    during system suspend.

    Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
    Tested-by: Simon Horman <horms@verge.net.au>
    Acked-by: Paul Mundt <lethal@linux-sh.org>
    ---

    The only change with respect to the previous version is the hunk in
    pm_genpd_restore_noirq() which only affects hibernation.

    Thanks,
    Rafael

    ---
    drivers/base/power/domain.c | 37 +++++++++++++++++++++++++++++++------
    include/linux/pm_domain.h | 3 +++
    2 files changed, 34 insertions(+), 6 deletions(-)

    Index: linux/drivers/base/power/domain.c
    ===================================================================
    --- linux.orig/drivers/base/power/domain.c
    +++ linux/drivers/base/power/domain.c
    @@ -366,7 +366,7 @@ static int pm_genpd_poweroff(struct gene
    not_suspended = 0;
    list_for_each_entry(pdd, &genpd->dev_list, list_node)
    if (pdd->dev->driver && (!pm_runtime_suspended(pdd->dev)
    - || pdd->dev->power.irq_safe))
    + || pdd->dev->power.irq_safe || to_gpd_data(pdd)->always_on))
    not_suspended++;

    if (not_suspended > genpd->in_progress)
    @@ -503,6 +503,9 @@ static int pm_genpd_runtime_suspend(stru

    might_sleep_if(!genpd->dev_irq_safe);

    + if (dev_gpd_data(dev)->always_on)
    + return -EBUSY;
    +
    stop_ok = genpd->gov ? genpd->gov->stop_ok : NULL;
    if (stop_ok && !stop_ok(dev))
    return -EBUSY;
    @@ -859,7 +862,7 @@ static int pm_genpd_suspend_noirq(struct
    if (IS_ERR(genpd))
    return -EINVAL;

    - if (genpd->suspend_power_off
    + if (genpd->suspend_power_off || dev_gpd_data(dev)->always_on
    || (dev->power.wakeup_path && genpd_dev_active_wakeup(genpd, dev)))
    return 0;

    @@ -892,7 +895,7 @@ static int pm_genpd_resume_noirq(struct
    if (IS_ERR(genpd))
    return -EINVAL;

    - if (genpd->suspend_power_off
    + if (genpd->suspend_power_off || dev_gpd_data(dev)->always_on
    || (dev->power.wakeup_path && genpd_dev_active_wakeup(genpd, dev)))
    return 0;

    @@ -1012,7 +1015,8 @@ static int pm_genpd_freeze_noirq(struct
    if (IS_ERR(genpd))
    return -EINVAL;

    - return genpd->suspend_power_off ? 0 : genpd_stop_dev(genpd, dev);
    + return genpd->suspend_power_off || dev_gpd_data(dev)->always_on ?
    + 0 : genpd_stop_dev(genpd, dev);
    }

    /**
    @@ -1032,7 +1036,8 @@ static int pm_genpd_thaw_noirq(struct de
    if (IS_ERR(genpd))
    return -EINVAL;

    - return genpd->suspend_power_off ? 0 : genpd_start_dev(genpd, dev);
    + return genpd->suspend_power_off || dev_gpd_data(dev)->always_on ?
    + 0 : genpd_start_dev(genpd, dev);
    }

    /**
    @@ -1125,7 +1130,7 @@ static int pm_genpd_restore_noirq(struct

    pm_genpd_poweron(genpd);

    - return genpd_start_dev(genpd, dev);
    + return dev_gpd_data(dev)->always_on ? 0 : genpd_start_dev(genpd, dev);
    }

    /**
    @@ -1289,6 +1294,26 @@ int pm_genpd_remove_device(struct generi
    }

    /**
    + * pm_genpd_dev_always_on - Set/unset the "always on" flag for a given device.
    + * @dev: Device to set/unset the flag for.
    + * @val: The new value of the device's "always on" flag.
    + */
    +void pm_genpd_dev_always_on(struct device *dev, bool val)
    +{
    + struct pm_subsys_data *psd;
    + unsigned long flags;
    +
    + spin_lock_irqsave(&dev->power.lock, flags);
    +
    + psd = dev_to_psd(dev);
    + if (psd && psd->domain_data)
    + to_gpd_data(psd->domain_data)->always_on = val;
    +
    + spin_unlock_irqrestore(&dev->power.lock, flags);
    +}
    +EXPORT_SYMBOL_GPL(pm_genpd_dev_always_on);
    +
    +/**
    * pm_genpd_add_subdomain - Add a subdomain to an I/O PM domain.
    * @genpd: Master PM domain to add the subdomain to.
    * @subdomain: Subdomain to be added.
    Index: linux/include/linux/pm_domain.h
    ===================================================================
    --- linux.orig/include/linux/pm_domain.h
    +++ linux/include/linux/pm_domain.h
    @@ -97,6 +97,7 @@ struct generic_pm_domain_data {
    struct gpd_dev_ops ops;
    struct gpd_timing_data td;
    bool need_restore;
    + bool always_on;
    };

    #ifdef CONFIG_PM_GENERIC_DOMAINS
    @@ -125,6 +126,7 @@ static inline int pm_genpd_add_device(st

    extern int pm_genpd_remove_device(struct generic_pm_domain *genpd,
    struct device *dev);
    +extern void pm_genpd_dev_always_on(struct device *dev, bool val);
    extern int pm_genpd_add_subdomain(struct generic_pm_domain *genpd,
    struct generic_pm_domain *new_subdomain);
    extern int pm_genpd_remove_subdomain(struct generic_pm_domain *genpd,
    @@ -167,6 +169,7 @@ static inline int pm_genpd_remove_device
    {
    return -ENOSYS;
    }
    +static inline void pm_genpd_dev_always_on(struct device *dev, bool val) {}
    static inline int pm_genpd_add_subdomain(struct generic_pm_domain *genpd,
    struct generic_pm_domain *new_sd)
    {

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