[PATCH 06/10] ARM: OMAP2+: powerdomain/clockdomain: add a per-powerdomain spinlock

Jean Pihet jean.pihet at newoldbits.com
Wed Dec 12 04:41:07 EST 2012


Paul,

On Sun, Dec 9, 2012 at 2:23 AM, Paul Walmsley <paul at pwsan.com> wrote:

> Add a per-powerdomain spinlock.  Use that instead of the clockdomain
> spinlock.  Add pwrdm_lock()/pwrdm_unlock() functions to allow other
> code to acquire or release the powerdomain spinlock without reaching
> directly into the struct powerdomain.
>
Since clockdomains are part of powerdomains it seems weird for the
clockdomain code to take a powerdoamin lock.
Is there a reason why the powerdomain could not take the lock before
calling the clockdomain functions?

Also, are the lock and nolock version the clockdomain function needed?

Regards,
Jean


>
> Signed-off-by: Paul Walmsley <paul at pwsan.com>
> Cc: Jean Pihet <jean.pihet at newoldbits.com>
> ---
>  arch/arm/mach-omap2/clockdomain-powerdomain.h |   22 +++
>  arch/arm/mach-omap2/clockdomain.c             |  161
> +++++++++++++++++--------
>  arch/arm/mach-omap2/clockdomain.h             |    6 +
>  arch/arm/mach-omap2/powerdomain-clockdomain.h |   27 ++++
>  arch/arm/mach-omap2/powerdomain.c             |   56 ++++++++-
>  arch/arm/mach-omap2/powerdomain.h             |   11 +-
>  6 files changed, 219 insertions(+), 64 deletions(-)
>  create mode 100644 arch/arm/mach-omap2/clockdomain-powerdomain.h
>  create mode 100644 arch/arm/mach-omap2/powerdomain-clockdomain.h
>
> diff --git a/arch/arm/mach-omap2/clockdomain-powerdomain.h
> b/arch/arm/mach-omap2/clockdomain-powerdomain.h
> new file mode 100644
> index 0000000..8beee2d
> --- /dev/null
> +++ b/arch/arm/mach-omap2/clockdomain-powerdomain.h
> @@ -0,0 +1,22 @@
> +/*
> + * OMAP clockdomain framework functions for use only by the powerdomain
> code
> + *
> + * Copyright (C) 2012 Texas Instruments, Inc.
> + * Paul Walmsley
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#ifndef __ARCH_ARM_MACH_OMAP2_CLOCKDOMAIN_POWERDOMAIN_H
> +#define __ARCH_ARM_MACH_OMAP2_CLOCKDOMAIN_POWERDOMAIN_H
> +
> +#include "clockdomain.h"
> +
> +extern void clkdm_allow_idle_nolock(struct clockdomain *clkdm);
> +extern void clkdm_deny_idle_nolock(struct clockdomain *clkdm);
> +extern int clkdm_wakeup_nolock(struct clockdomain *clkdm);
> +extern int clkdm_sleep_nolock(struct clockdomain *clkdm);
> +
> +#endif
> diff --git a/arch/arm/mach-omap2/clockdomain.c
> b/arch/arm/mach-omap2/clockdomain.c
> index 18f65fd..2142dab 100644
> --- a/arch/arm/mach-omap2/clockdomain.c
> +++ b/arch/arm/mach-omap2/clockdomain.c
> @@ -30,6 +30,7 @@
>  #include "soc.h"
>  #include "clock.h"
>  #include "clockdomain.h"
> +#include "powerdomain-clockdomain.h"
>
>  /* clkdm_list contains all registered struct clockdomains */
>  static LIST_HEAD(clkdm_list);
> @@ -91,8 +92,6 @@ static int _clkdm_register(struct clockdomain *clkdm)
>
>         pwrdm_add_clkdm(pwrdm, clkdm);
>
> -       spin_lock_init(&clkdm->lock);
> -
>         pr_debug("clockdomain: registered %s\n", clkdm->name);
>
>         return 0;
> @@ -733,18 +732,17 @@ int clkdm_clear_all_sleepdeps(struct clockdomain
> *clkdm)
>  }
>
>  /**
> - * clkdm_sleep - force clockdomain sleep transition
> + * clkdm_sleep_nolock - force clockdomain sleep transition (lockless)
>   * @clkdm: struct clockdomain *
>   *
>   * Instruct the CM to force a sleep transition on the specified
> - * clockdomain @clkdm.  Returns -EINVAL if @clkdm is NULL or if
> - * clockdomain does not support software-initiated sleep; 0 upon
> - * success.
> + * clockdomain @clkdm.  Only for use by the powerdomain code.  Returns
> + * -EINVAL if @clkdm is NULL or if clockdomain does not support
> + * software-initiated sleep; 0 upon success.
>   */
> -int clkdm_sleep(struct clockdomain *clkdm)
> +int clkdm_sleep_nolock(struct clockdomain *clkdm)
>  {
>         int ret;
> -       unsigned long flags;
>
>         if (!clkdm)
>                 return -EINVAL;
> @@ -760,27 +758,45 @@ int clkdm_sleep(struct clockdomain *clkdm)
>
>         pr_debug("clockdomain: forcing sleep on %s\n", clkdm->name);
>
> -       spin_lock_irqsave(&clkdm->lock, flags);
>         clkdm->_flags &= ~_CLKDM_FLAG_HWSUP_ENABLED;
>         ret = arch_clkdm->clkdm_sleep(clkdm);
> -       ret |= pwrdm_state_switch(clkdm->pwrdm.ptr);
> -       spin_unlock_irqrestore(&clkdm->lock, flags);
> +       ret |= pwrdm_state_switch_nolock(clkdm->pwrdm.ptr);
> +
>         return ret;
>  }
>
>  /**
> - * clkdm_wakeup - force clockdomain wakeup transition
> + * clkdm_sleep - force clockdomain sleep transition
>   * @clkdm: struct clockdomain *
>   *
> - * Instruct the CM to force a wakeup transition on the specified
> - * clockdomain @clkdm.  Returns -EINVAL if @clkdm is NULL or if the
> - * clockdomain does not support software-controlled wakeup; 0 upon
> + * Instruct the CM to force a sleep transition on the specified
> + * clockdomain @clkdm.  Returns -EINVAL if @clkdm is NULL or if
> + * clockdomain does not support software-initiated sleep; 0 upon
>   * success.
>   */
> -int clkdm_wakeup(struct clockdomain *clkdm)
> +int clkdm_sleep(struct clockdomain *clkdm)
> +{
> +       int ret;
> +
> +       pwrdm_lock(clkdm->pwrdm.ptr);
> +       ret = clkdm_sleep_nolock(clkdm);
> +       pwrdm_unlock(clkdm->pwrdm.ptr);
> +
> +       return ret;
> +}
> +
> +/**
> + * clkdm_wakeup_nolock - force clockdomain wakeup transition (lockless)
> + * @clkdm: struct clockdomain *
> + *
> + * Instruct the CM to force a wakeup transition on the specified
> + * clockdomain @clkdm.  Only for use by the powerdomain code.  Returns
> + * -EINVAL if @clkdm is NULL or if the clockdomain does not support
> + * software-controlled wakeup; 0 upon success.
> + */
> +int clkdm_wakeup_nolock(struct clockdomain *clkdm)
>  {
>         int ret;
> -       unsigned long flags;
>
>         if (!clkdm)
>                 return -EINVAL;
> @@ -796,28 +812,46 @@ int clkdm_wakeup(struct clockdomain *clkdm)
>
>         pr_debug("clockdomain: forcing wakeup on %s\n", clkdm->name);
>
> -       spin_lock_irqsave(&clkdm->lock, flags);
>         clkdm->_flags &= ~_CLKDM_FLAG_HWSUP_ENABLED;
>         ret = arch_clkdm->clkdm_wakeup(clkdm);
> -       ret |= pwrdm_state_switch(clkdm->pwrdm.ptr);
> -       spin_unlock_irqrestore(&clkdm->lock, flags);
> +       ret |= pwrdm_state_switch_nolock(clkdm->pwrdm.ptr);
> +
>         return ret;
>  }
>
>  /**
> - * clkdm_allow_idle - enable hwsup idle transitions for clkdm
> + * clkdm_wakeup - force clockdomain wakeup transition
>   * @clkdm: struct clockdomain *
>   *
> - * Allow the hardware to automatically switch the clockdomain @clkdm into
> - * active or idle states, as needed by downstream clocks.  If the
> + * Instruct the CM to force a wakeup transition on the specified
> + * clockdomain @clkdm.  Returns -EINVAL if @clkdm is NULL or if the
> + * clockdomain does not support software-controlled wakeup; 0 upon
> + * success.
> + */
> +int clkdm_wakeup(struct clockdomain *clkdm)
> +{
> +       int ret;
> +
> +       pwrdm_lock(clkdm->pwrdm.ptr);
> +       ret = clkdm_wakeup_nolock(clkdm);
> +       pwrdm_unlock(clkdm->pwrdm.ptr);
> +
> +       return ret;
> +}
> +
> +/**
> + * clkdm_allow_idle_nolock - enable hwsup idle transitions for clkdm
> + * @clkdm: struct clockdomain *
> + *
> + * Allow the hardware to automatically switch the clockdomain @clkdm
> + * into active or idle states, as needed by downstream clocks.  If the
>   * clockdomain has any downstream clocks enabled in the clock
>   * framework, wkdep/sleepdep autodependencies are added; this is so
> - * device drivers can read and write to the device.  No return value.
> + * device drivers can read and write to the device.  Only for use by
> + * the powerdomain code.  No return value.
>   */
> -void clkdm_allow_idle(struct clockdomain *clkdm)
> +void clkdm_allow_idle_nolock(struct clockdomain *clkdm)
>  {
> -       unsigned long flags;
> -
>         if (!clkdm)
>                 return;
>
> @@ -833,11 +867,26 @@ void clkdm_allow_idle(struct clockdomain *clkdm)
>         pr_debug("clockdomain: enabling automatic idle transitions for
> %s\n",
>                  clkdm->name);
>
> -       spin_lock_irqsave(&clkdm->lock, flags);
>         clkdm->_flags |= _CLKDM_FLAG_HWSUP_ENABLED;
>         arch_clkdm->clkdm_allow_idle(clkdm);
> -       pwrdm_state_switch(clkdm->pwrdm.ptr);
> -       spin_unlock_irqrestore(&clkdm->lock, flags);
> +       pwrdm_state_switch_nolock(clkdm->pwrdm.ptr);
> +}
> +
> +/**
> + * clkdm_allow_idle - enable hwsup idle transitions for clkdm
> + * @clkdm: struct clockdomain *
> + *
> + * Allow the hardware to automatically switch the clockdomain @clkdm into
> + * active or idle states, as needed by downstream clocks.  If the
> + * clockdomain has any downstream clocks enabled in the clock
> + * framework, wkdep/sleepdep autodependencies are added; this is so
> + * device drivers can read and write to the device.  No return value.
> + */
> +void clkdm_allow_idle(struct clockdomain *clkdm)
> +{
> +       pwrdm_lock(clkdm->pwrdm.ptr);
> +       clkdm_allow_idle_nolock(clkdm);
> +       pwrdm_unlock(clkdm->pwrdm.ptr);
>  }
>
>  /**
> @@ -847,12 +896,11 @@ void clkdm_allow_idle(struct clockdomain *clkdm)
>   * Prevent the hardware from automatically switching the clockdomain
>   * @clkdm into inactive or idle states.  If the clockdomain has
>   * downstream clocks enabled in the clock framework, wkdep/sleepdep
> - * autodependencies are removed.  No return value.
> + * autodependencies are removed.  Only for use by the powerdomain
> + * code.  No return value.
>   */
> -void clkdm_deny_idle(struct clockdomain *clkdm)
> +void clkdm_deny_idle_nolock(struct clockdomain *clkdm)
>  {
> -       unsigned long flags;
> -
>         if (!clkdm)
>                 return;
>
> @@ -868,11 +916,25 @@ void clkdm_deny_idle(struct clockdomain *clkdm)
>         pr_debug("clockdomain: disabling automatic idle transitions for
> %s\n",
>                  clkdm->name);
>
> -       spin_lock_irqsave(&clkdm->lock, flags);
>         clkdm->_flags &= ~_CLKDM_FLAG_HWSUP_ENABLED;
>         arch_clkdm->clkdm_deny_idle(clkdm);
> -       pwrdm_state_switch(clkdm->pwrdm.ptr);
> -       spin_unlock_irqrestore(&clkdm->lock, flags);
> +       pwrdm_state_switch_nolock(clkdm->pwrdm.ptr);
> +}
> +
> +/**
> + * clkdm_deny_idle - disable hwsup idle transitions for clkdm
> + * @clkdm: struct clockdomain *
> + *
> + * Prevent the hardware from automatically switching the clockdomain
> + * @clkdm into inactive or idle states.  If the clockdomain has
> + * downstream clocks enabled in the clock framework, wkdep/sleepdep
> + * autodependencies are removed.  No return value.
> + */
> +void clkdm_deny_idle(struct clockdomain *clkdm)
> +{
> +       pwrdm_lock(clkdm->pwrdm.ptr);
> +       clkdm_deny_idle_nolock(clkdm);
> +       pwrdm_unlock(clkdm->pwrdm.ptr);
>  }
>
>  /**
> @@ -889,14 +951,11 @@ void clkdm_deny_idle(struct clockdomain *clkdm)
>  bool clkdm_in_hwsup(struct clockdomain *clkdm)
>  {
>         bool ret;
> -       unsigned long flags;
>
>         if (!clkdm)
>                 return false;
>
> -       spin_lock_irqsave(&clkdm->lock, flags);
>         ret = (clkdm->_flags & _CLKDM_FLAG_HWSUP_ENABLED) ? true : false;
> -       spin_unlock_irqrestore(&clkdm->lock, flags);
>
>         return ret;
>  }
> @@ -922,12 +981,10 @@ bool clkdm_missing_idle_reporting(struct clockdomain
> *clkdm)
>
>  static int _clkdm_clk_hwmod_enable(struct clockdomain *clkdm)
>  {
> -       unsigned long flags;
> -
>         if (!clkdm || !arch_clkdm || !arch_clkdm->clkdm_clk_enable)
>                 return -EINVAL;
>
> -       spin_lock_irqsave(&clkdm->lock, flags);
> +       pwrdm_lock(clkdm->pwrdm.ptr);
>
>         /*
>          * For arch's with no autodeps, clkcm_clk_enable
> @@ -935,13 +992,13 @@ static int _clkdm_clk_hwmod_enable(struct
> clockdomain *clkdm)
>          * enabled, so the clkdm can be force woken up.
>          */
>         if ((atomic_inc_return(&clkdm->usecount) > 1) && autodeps) {
> -               spin_unlock_irqrestore(&clkdm->lock, flags);
> +               pwrdm_unlock(clkdm->pwrdm.ptr);
>                 return 0;
>         }
>
>         arch_clkdm->clkdm_clk_enable(clkdm);
> -       pwrdm_state_switch(clkdm->pwrdm.ptr);
> -       spin_unlock_irqrestore(&clkdm->lock, flags);
> +       pwrdm_state_switch_nolock(clkdm->pwrdm.ptr);
> +       pwrdm_unlock(clkdm->pwrdm.ptr);
>
>         pr_debug("clockdomain: %s: enabled\n", clkdm->name);
>
> @@ -950,27 +1007,25 @@ static int _clkdm_clk_hwmod_enable(struct
> clockdomain *clkdm)
>
>  static int _clkdm_clk_hwmod_disable(struct clockdomain *clkdm)
>  {
> -       unsigned long flags;
> -
>         if (!clkdm || !arch_clkdm || !arch_clkdm->clkdm_clk_disable)
>                 return -EINVAL;
>
> -       spin_lock_irqsave(&clkdm->lock, flags);
> +       pwrdm_lock(clkdm->pwrdm.ptr);
>
>         if (atomic_read(&clkdm->usecount) == 0) {
> -               spin_unlock_irqrestore(&clkdm->lock, flags);
> +               pwrdm_unlock(clkdm->pwrdm.ptr);
>                 WARN_ON(1); /* underflow */
>                 return -ERANGE;
>         }
>
>         if (atomic_dec_return(&clkdm->usecount) > 0) {
> -               spin_unlock_irqrestore(&clkdm->lock, flags);
> +               pwrdm_unlock(clkdm->pwrdm.ptr);
>                 return 0;
>         }
>
>         arch_clkdm->clkdm_clk_disable(clkdm);
> -       pwrdm_state_switch(clkdm->pwrdm.ptr);
> -       spin_unlock_irqrestore(&clkdm->lock, flags);
> +       pwrdm_state_switch_nolock(clkdm->pwrdm.ptr);
> +       pwrdm_unlock(clkdm->pwrdm.ptr);
>
>         pr_debug("clockdomain: %s: disabled\n", clkdm->name);
>
> diff --git a/arch/arm/mach-omap2/clockdomain.h
> b/arch/arm/mach-omap2/clockdomain.h
> index bc42446..e7f1b4b 100644
> --- a/arch/arm/mach-omap2/clockdomain.h
> +++ b/arch/arm/mach-omap2/clockdomain.h
> @@ -15,7 +15,6 @@
>  #define __ARCH_ARM_MACH_OMAP2_CLOCKDOMAIN_H
>
>  #include <linux/init.h>
> -#include <linux/spinlock.h>
>
>  #include "powerdomain.h"
>  #include "clock.h"
> @@ -139,7 +138,6 @@ struct clockdomain {
>         struct clkdm_dep *sleepdep_srcs;
>         atomic_t usecount;
>         struct list_head node;
> -       spinlock_t lock;
>  };
>
>  /**
> @@ -196,12 +194,16 @@ int clkdm_del_sleepdep(struct clockdomain *clkdm1,
> struct clockdomain *clkdm2);
>  int clkdm_read_sleepdep(struct clockdomain *clkdm1, struct clockdomain
> *clkdm2);
>  int clkdm_clear_all_sleepdeps(struct clockdomain *clkdm);
>
> +void clkdm_allow_idle_nolock(struct clockdomain *clkdm);
>  void clkdm_allow_idle(struct clockdomain *clkdm);
> +void clkdm_deny_idle_nolock(struct clockdomain *clkdm);
>  void clkdm_deny_idle(struct clockdomain *clkdm);
>  bool clkdm_in_hwsup(struct clockdomain *clkdm);
>  bool clkdm_missing_idle_reporting(struct clockdomain *clkdm);
>
> +int clkdm_wakeup_nolock(struct clockdomain *clkdm);
>  int clkdm_wakeup(struct clockdomain *clkdm);
> +int clkdm_sleep_nolock(struct clockdomain *clkdm);
>  int clkdm_sleep(struct clockdomain *clkdm);
>
>  int clkdm_clk_enable(struct clockdomain *clkdm, struct clk *clk);
> diff --git a/arch/arm/mach-omap2/powerdomain-clockdomain.h
> b/arch/arm/mach-omap2/powerdomain-clockdomain.h
> new file mode 100644
> index 0000000..e404eec
> --- /dev/null
> +++ b/arch/arm/mach-omap2/powerdomain-clockdomain.h
> @@ -0,0 +1,27 @@
> +/*
> + * OMAP powerdomain functions only for use by the OMAP clockdomain code
> + *
> + * Copyright (C) 2012 Texas Instruments, Inc.
> + * Paul Walmsley
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * The point of this file is to try to prevent other code outside of
> + * clockdomain.c from calling the functions listed herein.  Yes, this
> + * means you.
> + */
> +
> +#ifndef __ARCH_ARM_MACH_OMAP2_POWERDOMAIN_CLOCKDOMAIN_H
> +#define __ARCH_ARM_MACH_OMAP2_POWERDOMAIN_CLOCKDOMAIN_H
> +
> +#include <linux/types.h>
> +
> +#include "powerdomain.h"
> +
> +extern void pwrdm_lock(struct powerdomain *pwrdm);
> +extern void pwrdm_unlock(struct powerdomain *pwrdm);
> +extern int pwrdm_state_switch_nolock(struct powerdomain *pwrdm);
> +
> +#endif
> diff --git a/arch/arm/mach-omap2/powerdomain.c
> b/arch/arm/mach-omap2/powerdomain.c
> index 05f00660..2a5f15b 100644
> --- a/arch/arm/mach-omap2/powerdomain.c
> +++ b/arch/arm/mach-omap2/powerdomain.c
> @@ -19,6 +19,7 @@
>  #include <linux/list.h>
>  #include <linux/errno.h>
>  #include <linux/string.h>
> +#include <linux/spinlock.h>
>  #include <trace/events/power.h>
>
>  #include "cm2xxx_3xxx.h"
> @@ -31,6 +32,7 @@
>
>  #include "powerdomain.h"
>  #include "clockdomain.h"
> +#include "clockdomain-powerdomain.h"
>
>  #include "soc.h"
>  #include "pm.h"
> @@ -101,6 +103,7 @@ static int _pwrdm_register(struct powerdomain *pwrdm)
>         pwrdm->voltdm.ptr = voltdm;
>         INIT_LIST_HEAD(&pwrdm->voltdm_node);
>         voltdm_add_pwrdm(voltdm, pwrdm);
> +       spin_lock_init(&pwrdm->_lock);
>
>         list_add(&pwrdm->node, &pwrdm_list);
>
> @@ -276,6 +279,30 @@ int pwrdm_complete_init(void)
>  }
>
>  /**
> + * pwrdm_lock - acquire a Linux spinlock on a powerdomain
> + * @pwrdm: struct powerdomain * to lock
> + *
> + * Acquire the powerdomain spinlock on @pwrdm.  No return value.
> + */
> +void pwrdm_lock(struct powerdomain *pwrdm)
> +       __acquires(&pwrdm->_lock)
> +{
> +       spin_lock_irqsave(&pwrdm->_lock, pwrdm->_lock_flags);
> +}
> +
> +/**
> + * pwrdm_unlock - release a Linux spinlock on a powerdomain
> + * @pwrdm: struct powerdomain * to unlock
> + *
> + * Release the powerdomain spinlock on @pwrdm.  No return value.
> + */
> +void pwrdm_unlock(struct powerdomain *pwrdm)
> +       __releases(&pwrdm->_lock)
> +{
> +       spin_unlock_irqrestore(&pwrdm->_lock, pwrdm->_lock_flags);
> +}
> +
> +/**
>   * pwrdm_lookup - look up a powerdomain by name, return a pointer
>   * @name: name of powerdomain
>   *
> @@ -921,7 +948,7 @@ bool pwrdm_has_hdwr_sar(struct powerdomain *pwrdm)
>         return (pwrdm && pwrdm->flags & PWRDM_HAS_HDWR_SAR) ? 1 : 0;
>  }
>
> -int pwrdm_state_switch(struct powerdomain *pwrdm)
> +int pwrdm_state_switch_nolock(struct powerdomain *pwrdm)
>  {
>         int ret;
>
> @@ -935,6 +962,17 @@ int pwrdm_state_switch(struct powerdomain *pwrdm)
>         return ret;
>  }
>
> +int __deprecated pwrdm_state_switch(struct powerdomain *pwrdm)
> +{
> +       int ret;
> +
> +       pwrdm_lock(pwrdm);
> +       ret = pwrdm_state_switch_nolock(pwrdm);
> +       pwrdm_unlock(pwrdm);
> +
> +       return ret;
> +}
> +
>  int pwrdm_pre_transition(struct powerdomain *pwrdm)
>  {
>         if (pwrdm)
> @@ -973,7 +1011,7 @@ static u8 _pwrdm_save_clkdm_state_and_activate(struct
> powerdomain *pwrdm,
>                         sleep_switch = LOWPOWERSTATE_SWITCH;
>                 } else {
>                         *hwsup = clkdm_in_hwsup(pwrdm->pwrdm_clkdms[0]);
> -                       clkdm_wakeup(pwrdm->pwrdm_clkdms[0]);
> +                       clkdm_wakeup_nolock(pwrdm->pwrdm_clkdms[0]);
>                         sleep_switch = FORCEWAKEUP_SWITCH;
>                 }
>         } else {
> @@ -989,15 +1027,15 @@ static void _pwrdm_restore_clkdm_state(struct
> powerdomain *pwrdm,
>         switch (sleep_switch) {
>         case FORCEWAKEUP_SWITCH:
>                 if (hwsup)
> -                       clkdm_allow_idle(pwrdm->pwrdm_clkdms[0]);
> +                       clkdm_allow_idle_nolock(pwrdm->pwrdm_clkdms[0]);
>                 else
> -                       clkdm_sleep(pwrdm->pwrdm_clkdms[0]);
> +                       clkdm_sleep_nolock(pwrdm->pwrdm_clkdms[0]);
>                 break;
>         case LOWPOWERSTATE_SWITCH:
>                 if (pwrdm->flags & PWRDM_HAS_LOWPOWERSTATECHANGE &&
>                     arch_pwrdm->pwrdm_set_lowpwrstchange)
>                         arch_pwrdm->pwrdm_set_lowpwrstchange(pwrdm);
> -               pwrdm_state_switch(pwrdm);
> +               pwrdm_state_switch_nolock(pwrdm);
>                 break;
>         }
>  }
> @@ -1021,9 +1059,13 @@ int omap_set_pwrdm_state(struct powerdomain *pwrdm,
> u8 pwrst)
>                 pwrst--;
>         }
>
> +       pwrdm_lock(pwrdm);
> +
>         next_pwrst = pwrdm_read_next_pwrst(pwrdm);
> -       if (next_pwrst == pwrst)
> +       if (next_pwrst == pwrst) {
> +               pwrdm_unlock(pwrdm);
>                 return ret;
> +       }
>
>         sleep_switch = _pwrdm_save_clkdm_state_and_activate(pwrdm, pwrst,
>                                                             &hwsup);
> @@ -1035,6 +1077,8 @@ int omap_set_pwrdm_state(struct powerdomain *pwrdm,
> u8 pwrst)
>
>         _pwrdm_restore_clkdm_state(pwrdm, sleep_switch, hwsup);
>
> +       pwrdm_unlock(pwrdm);
> +
>         return ret;
>  }
>
> diff --git a/arch/arm/mach-omap2/powerdomain.h
> b/arch/arm/mach-omap2/powerdomain.h
> index 1edb3b7..83b4892 100644
> --- a/arch/arm/mach-omap2/powerdomain.h
> +++ b/arch/arm/mach-omap2/powerdomain.h
> @@ -19,8 +19,7 @@
>
>  #include <linux/types.h>
>  #include <linux/list.h>
> -
> -#include <linux/atomic.h>
> +#include <linux/spinlock.h>
>
>  #include "voltage.h"
>
> @@ -103,6 +102,8 @@ struct powerdomain;
>   * @state_counter:
>   * @timer:
>   * @state_timer:
> + * @_lock: spinlock used to serialize powerdomain and some clockdomain ops
> + * @_lock_flags: stored flags when @_lock is taken
>   *
>   * @prcm_partition possible values are defined in mach-omap2/prcm44xx.h.
>   */
> @@ -127,7 +128,8 @@ struct powerdomain {
>         unsigned state_counter[PWRDM_MAX_PWRSTS];
>         unsigned ret_logic_off_counter;
>         unsigned ret_mem_off_counter[PWRDM_MAX_MEM_BANKS];
> -
> +       spinlock_t _lock;
> +       unsigned long _lock_flags;
>         const u8 pwrstctrl_offs;
>         const u8 pwrstst_offs;
>         const u32 logicretstate_mask;
> @@ -225,6 +227,7 @@ int pwrdm_enable_hdwr_sar(struct powerdomain *pwrdm);
>  int pwrdm_disable_hdwr_sar(struct powerdomain *pwrdm);
>  bool pwrdm_has_hdwr_sar(struct powerdomain *pwrdm);
>
> +int pwrdm_state_switch_nolock(struct powerdomain *pwrdm);
>  int pwrdm_state_switch(struct powerdomain *pwrdm);
>  int pwrdm_pre_transition(struct powerdomain *pwrdm);
>  int pwrdm_post_transition(struct powerdomain *pwrdm);
> @@ -252,5 +255,7 @@ extern u32 omap2_pwrdm_get_mem_bank_stst_mask(u8 bank);
>  extern struct powerdomain wkup_omap2_pwrdm;
>  extern struct powerdomain gfx_omap2_pwrdm;
>
> +extern void pwrdm_lock(struct powerdomain *pwrdm);
> +extern void pwrdm_unlock(struct powerdomain *pwrdm);
>
>  #endif
>
>
>
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