On 11-01-16, 17:40, Stephen Boyd wrote:
- ret = regulator_set_voltage_triplet(reg, opp->u_volt_min, opp->u_volt,
This can't be called under an RCU read lock.
- rcu_read_lock();
This lock is held way too long.
- freq = clk_round_rate(clk, target_freq);
This can't be called under RCU.
- if ((long)freq <= 0)
freq = target_freq;
- old_freq = clk_get_rate(clk);
Same for this.
Some of these I figured out earlier (after sending the series), and fixed them by dropping rcu lock at certain points. But the problem is that we will be using opp/clk/reg here for almost the complete routine and the lock must be acquired for all the time.
(Untested for now)
-------------------------8<-------------------------
Subject: [PATCH] PM / OPP: Add dev_pm_opp_set_rate()
This adds a routine, dev_pm_opp_set_rate(), responsible for configuring power-supply and clock source for an OPP.
The OPP is found by matching against the target_freq passed to the routine. This shall replace similar code present in most of the OPP users and help simplify them a lot.
Signed-off-by: Viresh Kumar viresh.kumar@linaro.org --- drivers/base/power/opp/core.c | 155 ++++++++++++++++++++++++++++++++++++++++++ include/linux/pm_opp.h | 6 ++ 2 files changed, 161 insertions(+)
diff --git a/drivers/base/power/opp/core.c b/drivers/base/power/opp/core.c index 2b1e8cb3897f..ca6b31ab5c87 100644 --- a/drivers/base/power/opp/core.c +++ b/drivers/base/power/opp/core.c @@ -527,6 +527,161 @@ struct dev_pm_opp *dev_pm_opp_find_freq_floor(struct device *dev, } EXPORT_SYMBOL_GPL(dev_pm_opp_find_freq_floor);
+static int _set_opp_voltage(struct device *dev, struct regulator *reg, + unsigned long u_volt, unsigned long u_volt_min, + unsigned long u_volt_max) +{ + int ret; + + /* Regulator not be available for device */ + if (IS_ERR(reg)) { + dev_dbg(dev, "%s: regulator not available: %ld\n", __func__, + PTR_ERR(reg)); + return 0; + } + + dev_dbg(dev, "%s: voltages (mV): %lu %lu %lu\n", __func__, u_volt_min, + u_volt, u_volt_max); + + ret = regulator_set_voltage_triplet(reg, u_volt_min, u_volt, + u_volt_max); + if (ret) + dev_err(dev, "%s: failed to set voltage (%lu %lu %lu mV): %d\n", + __func__, u_volt_min, u_volt, u_volt_max, ret); + + return ret; +} + +/** + * dev_pm_opp_set_rate() - Configure new OPP based on frequency + * @dev: device for which we do this operation + * @target_freq: frequency to achieve + * + * This configures the power-supplies and clock source to the levels specified + * by the OPP corresponding to the target_freq. + * + * Locking: This function internally uses mutex locks to keep the integrity of + * the internal data structures. Callers should ensure that this function is + * *NOT* called under RCU protection or in contexts where mutex cannot be + * locked. + */ +int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq) +{ + struct device_opp *dev_opp; + struct dev_pm_opp *old_opp, *opp; + struct regulator *reg; + struct clk *clk; + unsigned long freq, old_freq; + unsigned long u_volt, u_volt_min, u_volt_max; + unsigned long ou_volt, ou_volt_min, ou_volt_max; + int ret; + + if (unlikely(!target_freq)) { + dev_err(dev, "%s: Invalid target frequency %lu\n", __func__, + target_freq); + return -EINVAL; + } + + /* + * Hold our list modification lock here as clk/regulator routines called + * below can possibly take another mutex, which isn't allowed within rcu + * locks. + */ + mutex_lock(&dev_opp_list_lock); + + dev_opp = _find_device_opp(dev); + if (IS_ERR(dev_opp)) { + dev_err(dev, "%s: device opp doesn't exist\n", __func__); + ret = PTR_ERR(dev_opp); + goto unlock; + } + + clk = dev_opp->clk; + if (IS_ERR(clk)) { + dev_err(dev, "%s: No clock available for the device\n", + __func__); + ret = -EINVAL; + goto unlock; + } + + freq = clk_round_rate(clk, target_freq); + if ((long)freq <= 0) + freq = target_freq; + + old_freq = clk_get_rate(clk); + + /* Return early if nothing to do */ + if (old_freq == freq) { + dev_dbg(dev, "%s: old/new frequencies (%lu Hz) are same, nothing to do\n", + __func__, freq); + ret = 0; + goto unlock; + } + + reg = dev_opp->regulator; + old_opp = dev_pm_opp_find_freq_ceil(dev, &old_freq); + opp = dev_pm_opp_find_freq_ceil(dev, &freq); + + if (IS_ERR(opp)) { + ret = PTR_ERR(opp); + dev_err(dev, "%s: failed to find OPP for freq %lu (%d)\n", + __func__, freq, ret); + goto unlock; + } + + u_volt = opp->u_volt; + u_volt_min = opp->u_volt_min; + u_volt_max = opp->u_volt_max; + + ou_volt = old_opp->u_volt; + ou_volt_min = old_opp->u_volt_min; + ou_volt_max = old_opp->u_volt_max; + + /* Scaling up? Scale voltage before frequency */ + if (freq > old_freq) { + ret = _set_opp_voltage(dev, reg, u_volt, u_volt_min, + u_volt_max); + if (ret) + goto restore_voltage; + } + + /* Change frequency */ + + dev_dbg(dev, "%s: switching OPP: %lu Hz --> %lu Hz\n", + __func__, old_freq, freq); + + ret = clk_set_rate(clk, freq); + if (ret) { + dev_err(dev, "%s: failed to set clock rate: %d\n", __func__, + ret); + goto restore_voltage; + } + + /* Scaling down? Scale voltage after frequency */ + if (freq < old_freq) { + ret = _set_opp_voltage(dev, reg, u_volt, u_volt_min, + u_volt_max); + if (ret) + goto restore_freq; + } + + mutex_unlock(&dev_opp_list_lock); + + return 0; + +restore_freq: + if (clk_set_rate(clk, old_freq)) + dev_err(dev, "%s: failed to restore old-freq (%lu Hz)\n", + __func__, old_freq); +restore_voltage: + /* This shouldn't harm if the voltages weren't updated earlier */ + _set_opp_voltage(dev, reg, ou_volt, ou_volt_min, ou_volt_max); +unlock: + mutex_unlock(&dev_opp_list_lock); + return ret; +} +EXPORT_SYMBOL_GPL(dev_pm_opp_set_rate); + /* List-dev Helpers */ static void _kfree_list_dev_rcu(struct rcu_head *head) { diff --git a/include/linux/pm_opp.h b/include/linux/pm_opp.h index 59da3d9e11ea..cccaf4a29e9f 100644 --- a/include/linux/pm_opp.h +++ b/include/linux/pm_opp.h @@ -64,6 +64,7 @@ int dev_pm_opp_set_prop_name(struct device *dev, const char *name); void dev_pm_opp_put_prop_name(struct device *dev); int dev_pm_opp_set_regulator(struct device *dev, const char *name); void dev_pm_opp_put_regulator(struct device *dev); +int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq); #else static inline unsigned long dev_pm_opp_get_voltage(struct dev_pm_opp *opp) { @@ -172,6 +173,11 @@ static inline int dev_pm_opp_set_regulator(struct device *dev, const char *name)
static inline void dev_pm_opp_put_regulator(struct device *dev) {}
+static inline int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq) +{ + return -EINVAL; +} + #endif /* CONFIG_PM_OPP */
#if defined(CONFIG_PM_OPP) && defined(CONFIG_OF)