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SubjectRe: [PATCH RFC 1/4] OPP: Add and export helper to update voltage
Date


On 6/27/2019 7:04 PM, Sibi Sankar wrote:
> Add and export 'dev_pm_opp_update_voltage' to find and update voltage
> of an opp for a given frequency. This will be useful to update the opps
> with voltages read back from firmware.
>
> Signed-off-by: Sibi Sankar <sibis@codeaurora.org>
> ---
> drivers/opp/core.c | 52 ++++++++++++++++++++++++++++++++++++++++++
> include/linux/pm_opp.h | 10 ++++++++
> 2 files changed, 62 insertions(+)
>
> diff --git a/drivers/opp/core.c b/drivers/opp/core.c
> index 68551d6366e6b..c85c04dc2c7de 100644
> --- a/drivers/opp/core.c
> +++ b/drivers/opp/core.c
> @@ -2197,6 +2197,58 @@ int dev_pm_opp_disable(struct device *dev, unsigned long freq)
> }
> EXPORT_SYMBOL_GPL(dev_pm_opp_disable);
>
> +/**
> + * dev_pm_opp_update_voltage() - Find and update voltage
> + * @dev: device for which we do this operation
> + * @freq: OPP frequency to update voltage
> + * @u_volt: voltage requested for this opp
> + *
> + * Find and update voltage of a disabled opp corresponding to the given
> + * frequency. This is useful only for devices with single power supply.
> + *
> + * Return: 0 if no modification was done OR modification was
> + * successful or a negative error value.
> + */
> +int dev_pm_opp_update_voltage(struct device *dev, unsigned long freq,
> + unsigned long u_volt)
> +{
> + struct dev_pm_opp *opp = ERR_PTR(-ENODEV);
> + struct opp_table *opp_table;
> + unsigned long tol;
> + int ret = 0;
> +
> + opp = dev_pm_opp_find_freq_exact(dev, freq, false);
> + if (IS_ERR(opp))
> + return PTR_ERR(opp);
> +
> + /* Find the opp_table */
> + opp_table = _find_opp_table(dev);

maybe you should look for the opp_table first and then the
opp? otherwise this check seems pretty redundant given the
above call would have failed if the opp table did not exist.

> + if (IS_ERR(opp_table)) {
> + ret = PTR_ERR(opp_table);
> + dev_err(dev, "%s: OPP table not found (%d)\n", __func__, ret);
> + goto put_opp;
> + }
> +
> + mutex_lock(&opp_table->lock);
> +
> + /* update only if the opp is disabled */
> + if (opp->available)
> + goto unlock;

should this throw a warning/error to indicate someone tried to
update this at a wrong time? and perhaps return an error instead of
success.

> +
> + tol = u_volt * opp_table->voltage_tolerance_v1 / 100;
> + opp->supplies[0].u_volt_min = u_volt - tol;
> + opp->supplies[0].u_volt = u_volt;
> + opp->supplies[0].u_volt_min = u_volt + tol;
> +
> +unlock:
> + mutex_unlock(&opp_table->lock);
> + dev_pm_opp_put_opp_table(opp_table);
> +put_opp:
> + dev_pm_opp_put(opp);
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(dev_pm_opp_update_voltage);
> +
> /**
> * dev_pm_opp_register_notifier() - Register OPP notifier for the device
> * @dev: Device for which notifier needs to be registered
> diff --git a/include/linux/pm_opp.h b/include/linux/pm_opp.h
> index 87fa09d93d8c2..a17c462974851 100644
> --- a/include/linux/pm_opp.h
> +++ b/include/linux/pm_opp.h
> @@ -130,6 +130,9 @@ int dev_pm_opp_enable(struct device *dev, unsigned long freq);
>
> int dev_pm_opp_disable(struct device *dev, unsigned long freq);
>
> +int dev_pm_opp_update_voltage(struct device *dev, unsigned long freq,
> + unsigned long u_volt);
> +
> int dev_pm_opp_register_notifier(struct device *dev, struct notifier_block *nb);
> int dev_pm_opp_unregister_notifier(struct device *dev, struct notifier_block *nb);
>
> @@ -261,6 +264,13 @@ static inline int dev_pm_opp_disable(struct device *dev, unsigned long freq)
> return 0;
> }
>
> +static inline int dev_pm_opp_update_voltage(struct device *dev,
> + unsigned long freq,
> + unsigned long u_volt)
> +{
> + return 0;
> +}
> +
> static inline int dev_pm_opp_register_notifier(struct device *dev, struct notifier_block *nb)
> {
> return -ENOTSUPP;
>

--
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