On 11-01-16, 17:25, Stephen Boyd wrote:
Doesn't rcu_read_lock() disable preemption sometimes? I don't think we can call regulator ops with preemption disabled because regulators use mutex locking. It looks like regulator_list_voltage() may take a mutex anyway.
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Subject: [PATCH] PM / OPP: Introduce dev_pm_opp_get_max_volt_latency()
In few use cases (like: cpufreq), it is desired to get the maximum voltage latency for changing OPPs. Add support for that.
Signed-off-by: Viresh Kumar viresh.kumar@linaro.org --- drivers/base/power/opp/core.c | 56 ++++++++++++++++++++++++++++++++++++++++++- include/linux/pm_opp.h | 6 +++++ 2 files changed, 61 insertions(+), 1 deletion(-)
diff --git a/drivers/base/power/opp/core.c b/drivers/base/power/opp/core.c index 052fc6b78dc3..62976d0bd61c 100644 --- a/drivers/base/power/opp/core.c +++ b/drivers/base/power/opp/core.c @@ -231,8 +231,62 @@ unsigned long dev_pm_opp_get_max_clock_latency(struct device *dev) EXPORT_SYMBOL_GPL(dev_pm_opp_get_max_clock_latency);
/** + * dev_pm_opp_get_max_volt_latency() - Get max voltage latency in nanoseconds + * @dev: device for which we do this operation + * + * Return: This function returns the max voltage latency in nanoseconds. + * + * Locking: This function takes rcu_read_lock(). + */ +unsigned long dev_pm_opp_get_max_volt_latency(struct device *dev) +{ + struct device_opp *dev_opp; + struct dev_pm_opp *opp; + struct regulator *reg; + unsigned long latency_ns = 0; + unsigned long min_uV = ~0, max_uV = 0; + int ret; + + /* + * Hold our list modification lock here as regulator_set_voltage_time() + * 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)) + goto unlock; + + reg = dev_opp->regulator; + /* Regulator may not be available for device */ + if (IS_ERR(reg)) + goto unlock; + + list_for_each_entry_rcu(opp, &dev_opp->opp_list, node) { + if (!opp->available) + continue; + + if (opp->u_volt_min < min_uV) + min_uV = opp->u_volt_min; + if (opp->u_volt_max > max_uV) + max_uV = opp->u_volt_max; + } + + ret = regulator_set_voltage_time(reg, min_uV, max_uV); + if (ret > 0) + latency_ns = ret * 1000; + +unlock: + mutex_unlock(&dev_opp_list_lock); + + return latency_ns; +} +EXPORT_SYMBOL_GPL(dev_pm_opp_get_max_volt_latency); + +/** * dev_pm_opp_get_suspend_opp() - Get suspend opp - * @dev: device for which we do this operation + * @dev: device for which we do this operation * * Return: This function returns pointer to the suspend opp if it is * defined and available, otherwise it returns NULL. diff --git a/include/linux/pm_opp.h b/include/linux/pm_opp.h index c70a18ac9c8a..5daa43058ac1 100644 --- a/include/linux/pm_opp.h +++ b/include/linux/pm_opp.h @@ -34,6 +34,7 @@ bool dev_pm_opp_is_turbo(struct dev_pm_opp *opp);
int dev_pm_opp_get_opp_count(struct device *dev); unsigned long dev_pm_opp_get_max_clock_latency(struct device *dev); +unsigned long dev_pm_opp_get_max_volt_latency(struct device *dev); struct dev_pm_opp *dev_pm_opp_get_suspend_opp(struct device *dev);
struct dev_pm_opp *dev_pm_opp_find_freq_exact(struct device *dev, @@ -88,6 +89,11 @@ static inline unsigned long dev_pm_opp_get_max_clock_latency(struct device *dev) return 0; }
+static inline unsigned long dev_pm_opp_get_max_volt_latency(struct device *dev) +{ + return 0; +} + static inline struct dev_pm_opp *dev_pm_opp_get_suspend_opp(struct device *dev) { return NULL;