Re: [v4, 2/8] cpufreq: mediatek: add clock enable for intermediate clock

Re: [v4, 2/8] cpufreq: mediatek: add clock enable for intermediate clock

[Viresh Kumar]

On 13-08-19, 21:31, Andrew-sh.Cheng wrote:
> From: "Andrew-sh.Cheng" <andrew-sh.cheng@mediatek.com>
> 
> Intermediate clock is not always enabled by ccf in different projects,
> so cpufreq should always enable it by itself.
> 
> Signed-off-by: Andrew-sh.Cheng <andrew-sh.cheng@mediatek.com>
> ---
>  drivers/cpufreq/mediatek-cpufreq.c | 13 ++++++++++++-
>  1 file changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/cpufreq/mediatek-cpufreq.c b/drivers/cpufreq/mediatek-cpufreq.c
> index a370577ffc73..acd9539e95de 100644
> --- a/drivers/cpufreq/mediatek-cpufreq.c
> +++ b/drivers/cpufreq/mediatek-cpufreq.c
> @@ -368,13 +368,17 @@ static int mtk_cpu_dvfs_info_init(struct mtk_cpu_dvfs_info *info, int cpu)
>  		goto out_free_resources;
>  	}
>  
> +	ret = clk_prepare_enable(inter_clk);
> +	if (ret)
> +		goto out_free_opp_table;
> +
>  	/* Search a safe voltage for intermediate frequency. */
>  	rate = clk_get_rate(inter_clk);
>  	opp = dev_pm_opp_find_freq_ceil(cpu_dev, &rate);
>  	if (IS_ERR(opp)) {
>  		pr_err("failed to get intermediate opp for cpu%d\n", cpu);
>  		ret = PTR_ERR(opp);
> -		goto out_free_opp_table;
> +		goto out_disable_clock;
>  	}
>  	info->intermediate_voltage = dev_pm_opp_get_voltage(opp);
>  	dev_pm_opp_put(opp);
> @@ -393,6 +397,9 @@ static int mtk_cpu_dvfs_info_init(struct mtk_cpu_dvfs_info *info, int cpu)
>  
>  	return 0;
>  
> +out_disable_clock:
> +	clk_disable_unprepare(inter_clk);
> +
>  out_free_opp_table:
>  	dev_pm_opp_of_cpumask_remove_table(&info->cpus);
>  
> @@ -419,6 +426,10 @@ static void mtk_cpu_dvfs_info_release(struct mtk_cpu_dvfs_info *info)
>  		clk_put(info->cpu_clk);
>  	if (!IS_ERR(info->inter_clk))
>  		clk_put(info->inter_clk);

Shouldn't you remove this part now ?

> +	if (!IS_ERR(info->inter_clk)) {
> +		clk_disable_unprepare(info->inter_clk);
> +		clk_put(info->inter_clk);
> +	}
>  
>  	dev_pm_opp_of_cpumask_remove_table(&info->cpus);
>  }
> -- 
> 2.12.5

-- 
viresh

Re: [v4, 1/8] cpufreq: mediatek: change to regulator_get_optional

[Viresh Kumar]

On 13-08-19, 21:31, Andrew-sh.Cheng wrote:
> From: "Andrew-sh.Cheng" <andrew-sh.cheng@mediatek.com>
> 
> For new mediatek chip mt8183,
> cci and little cluster share the same buck,
> so need to modify the attribute of regulator from exclusive to optional
> 
> Signed-off-by: Andrew-sh.Cheng <andrew-sh.cheng@mediatek.com>
> ---
>  drivers/cpufreq/mediatek-cpufreq.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/cpufreq/mediatek-cpufreq.c b/drivers/cpufreq/mediatek-cpufreq.c
> index f14f3a85f2f7..a370577ffc73 100644
> --- a/drivers/cpufreq/mediatek-cpufreq.c
> +++ b/drivers/cpufreq/mediatek-cpufreq.c
> @@ -338,7 +338,7 @@ static int mtk_cpu_dvfs_info_init(struct mtk_cpu_dvfs_info *info, int cpu)
>  		goto out_free_resources;
>  	}
>  
> -	proc_reg = regulator_get_exclusive(cpu_dev, "proc");
> +	proc_reg = regulator_get_optional(cpu_dev, "proc");
>  	if (IS_ERR(proc_reg)) {
>  		if (PTR_ERR(proc_reg) == -EPROBE_DEFER)
>  			pr_warn("proc regulator for cpu%d not ready, retry.\n",

Applied. Thanks.

-- 
viresh

Re: [v4, 3/8] cpufreq: mediatek: Add support for mt8183

[Viresh Kumar]

On 13-08-19, 21:31, Andrew-sh.Cheng wrote:
> From: "Andrew-sh.Cheng" <andrew-sh.cheng@mediatek.com>
> 
> Add compatible string for mediatek mt8183
> 
> Signed-off-by: Andrew-sh.Cheng <andrew-sh.cheng@mediatek.com>
> ---
>  drivers/cpufreq/cpufreq-dt-platdev.c | 1 +
>  drivers/cpufreq/mediatek-cpufreq.c   | 1 +
>  2 files changed, 2 insertions(+)
> 
> diff --git a/drivers/cpufreq/cpufreq-dt-platdev.c b/drivers/cpufreq/cpufreq-dt-platdev.c
> index 03dc4244ab00..0f7e837a264e 100644
> --- a/drivers/cpufreq/cpufreq-dt-platdev.c
> +++ b/drivers/cpufreq/cpufreq-dt-platdev.c
> @@ -117,6 +117,7 @@ static const struct of_device_id blacklist[] __initconst = {
>  	{ .compatible = "mediatek,mt817x", },
>  	{ .compatible = "mediatek,mt8173", },
>  	{ .compatible = "mediatek,mt8176", },
> +	{ .compatible = "mediatek,mt8183", },
>  
>  	{ .compatible = "nvidia,tegra124", },
>  	{ .compatible = "nvidia,tegra210", },
> diff --git a/drivers/cpufreq/mediatek-cpufreq.c b/drivers/cpufreq/mediatek-cpufreq.c
> index acd9539e95de..4dce41b18369 100644
> --- a/drivers/cpufreq/mediatek-cpufreq.c
> +++ b/drivers/cpufreq/mediatek-cpufreq.c
> @@ -546,6 +546,7 @@ static const struct of_device_id mtk_cpufreq_machines[] __initconst = {
>  	{ .compatible = "mediatek,mt817x", },
>  	{ .compatible = "mediatek,mt8173", },
>  	{ .compatible = "mediatek,mt8176", },
> +	{ .compatible = "mediatek,mt8183", },

Had to fix rebase conflict manually for this. Please always rebase on latest
linux-next.

Applied. Thanks.

-- 
viresh

Re: [v4, 7/8] cpufreq: mediatek: add opp notification for SVS support

[Viresh Kumar]

On 13-08-19, 21:31, Andrew-sh.Cheng wrote:
> From: "Andrew-sh.Cheng" <andrew-sh.cheng@mediatek.com>
> 
> cpufreq should listen opp notification and do proper actions
> when receiving disable and voltage adjustment events,
> which are triggered when SVS is enabled.
> 
> Signed-off-by: Andrew-sh.Cheng <andrew-sh.cheng@mediatek.com>
> ---
>  drivers/cpufreq/mediatek-cpufreq.c | 78 ++++++++++++++++++++++++++++++++++++++
>  1 file changed, 78 insertions(+)
> 
> diff --git a/drivers/cpufreq/mediatek-cpufreq.c b/drivers/cpufreq/mediatek-cpufreq.c
> index 4dce41b18369..9820c8003507 100644
> --- a/drivers/cpufreq/mediatek-cpufreq.c
> +++ b/drivers/cpufreq/mediatek-cpufreq.c
> @@ -42,6 +42,10 @@ struct mtk_cpu_dvfs_info {
>  	struct list_head list_head;
>  	int intermediate_voltage;
>  	bool need_voltage_tracking;
> +	struct mutex lock; /* avoid notify and policy race condition */
> +	struct notifier_block opp_nb;
> +	int opp_cpu;
> +	unsigned long opp_freq;
>  };
>  
>  static LIST_HEAD(dvfs_info_list);
> @@ -231,6 +235,7 @@ static int mtk_cpufreq_set_target(struct cpufreq_policy *policy,
>  	vproc = dev_pm_opp_get_voltage(opp);
>  	dev_pm_opp_put(opp);
>  
> +	mutex_lock(&info->lock);
>  	/*
>  	 * If the new voltage or the intermediate voltage is higher than the
>  	 * current voltage, scale up voltage first.
> @@ -242,6 +247,7 @@ static int mtk_cpufreq_set_target(struct cpufreq_policy *policy,
>  			pr_err("cpu%d: failed to scale up voltage!\n",
>  			       policy->cpu);
>  			mtk_cpufreq_set_voltage(info, old_vproc);
> +			mutex_unlock(&info->lock);
>  			return ret;
>  		}
>  	}
> @@ -253,6 +259,7 @@ static int mtk_cpufreq_set_target(struct cpufreq_policy *policy,
>  		       policy->cpu);
>  		mtk_cpufreq_set_voltage(info, old_vproc);
>  		WARN_ON(1);
> +		mutex_unlock(&info->lock);
>  		return ret;
>  	}
>  
> @@ -263,6 +270,7 @@ static int mtk_cpufreq_set_target(struct cpufreq_policy *policy,
>  		       policy->cpu);
>  		clk_set_parent(cpu_clk, armpll);
>  		mtk_cpufreq_set_voltage(info, old_vproc);
> +		mutex_unlock(&info->lock);
>  		return ret;
>  	}
>  
> @@ -273,6 +281,7 @@ static int mtk_cpufreq_set_target(struct cpufreq_policy *policy,
>  		       policy->cpu);
>  		mtk_cpufreq_set_voltage(info, inter_vproc);
>  		WARN_ON(1);
> +		mutex_unlock(&info->lock);
>  		return ret;
>  	}
>  
> @@ -288,15 +297,74 @@ static int mtk_cpufreq_set_target(struct cpufreq_policy *policy,
>  			clk_set_parent(cpu_clk, info->inter_clk);
>  			clk_set_rate(armpll, old_freq_hz);
>  			clk_set_parent(cpu_clk, armpll);
> +			mutex_unlock(&info->lock);
>  			return ret;
>  		}
>  	}
>  
> +	info->opp_freq = freq_hz;
> +	mutex_unlock(&info->lock);
> +
>  	return 0;
>  }
>  
>  #define DYNAMIC_POWER "dynamic-power-coefficient"
>  
> +static int mtk_cpufreq_opp_notifier(struct notifier_block *nb,
> +				    unsigned long event, void *data)
> +{
> +	struct dev_pm_opp *opp = data;
> +	struct dev_pm_opp *opp_item;
> +	struct mtk_cpu_dvfs_info *info =
> +		container_of(nb, struct mtk_cpu_dvfs_info, opp_nb);
> +	unsigned long freq, volt;
> +	struct cpufreq_policy *policy;
> +	int ret = 0;
> +
> +	if (event == OPP_EVENT_ADJUST_VOLTAGE) {
> +		freq = dev_pm_opp_get_freq(opp);
> +
> +		mutex_lock(&info->lock);
> +		if (info->opp_freq == freq) {
> +			volt = dev_pm_opp_get_voltage(opp);
> +			ret = mtk_cpufreq_set_voltage(info, volt);
> +			if (ret)
> +				dev_err(info->cpu_dev, "failed to scale voltage: %d\n",
> +					ret);
> +		}
> +		mutex_unlock(&info->lock);
> +	} else if (event == OPP_EVENT_DISABLE) {

Does this ever get called for your platform ? Why are you using opp disable ?
Maybe we can avoid it completely.

> +		freq = info->opp_freq;
> +		opp_item = dev_pm_opp_find_freq_ceil(info->cpu_dev, &freq);
> +		if (!IS_ERR(opp_item))
> +			dev_pm_opp_put(opp_item);
> +		else
> +			freq = 0;
> +
> +		/* case of current opp is disabled */
> +		if (freq == 0 || freq != info->opp_freq) {
> +			// find an enable opp item
> +			freq = 1;
> +			opp_item = dev_pm_opp_find_freq_ceil(info->cpu_dev,
> +							     &freq);
> +			if (!IS_ERR(opp_item)) {
> +				dev_pm_opp_put(opp_item);
> +				policy = cpufreq_cpu_get(info->opp_cpu);
> +				if (policy) {
> +					cpufreq_driver_target(policy,
> +						freq / 1000,
> +						CPUFREQ_RELATION_L);
> +					cpufreq_cpu_put(policy);
> +				}
> +			} else
> +				pr_err("%s: all opp items are disabled\n",
> +				       __func__);
> +		}
> +	}
> +
> +	return notifier_from_errno(ret);
> +}
> +
>  static int mtk_cpu_dvfs_info_init(struct mtk_cpu_dvfs_info *info, int cpu)
>  {
>  	struct device *cpu_dev;
> @@ -383,11 +451,21 @@ static int mtk_cpu_dvfs_info_init(struct mtk_cpu_dvfs_info *info, int cpu)
>  	info->intermediate_voltage = dev_pm_opp_get_voltage(opp);
>  	dev_pm_opp_put(opp);
>  
> +	info->opp_cpu = cpu;
> +	info->opp_nb.notifier_call = mtk_cpufreq_opp_notifier;
> +	ret = dev_pm_opp_register_notifier(cpu_dev, &info->opp_nb);
> +	if (ret) {
> +		pr_warn("cannot register opp notification\n");
> +		goto out_free_opp_table;
> +	}
> +
> +	mutex_init(&info->lock);
>  	info->cpu_dev = cpu_dev;
>  	info->proc_reg = proc_reg;
>  	info->sram_reg = IS_ERR(sram_reg) ? NULL : sram_reg;
>  	info->cpu_clk = cpu_clk;
>  	info->inter_clk = inter_clk;
> +	info->opp_freq = clk_get_rate(cpu_clk);
>  
>  	/*
>  	 * If SRAM regulator is present, software "voltage tracking" is needed
> -- 
> 2.12.5

-- 
viresh

Re: [v4, 7/8] cpufreq: mediatek: add opp notification for SVS support

[Viresh Kumar]

On 16-10-19, 10:43, andrew-sh.cheng wrote:
> This is due to SVS feature need to fix Vproc for calibration.
> When SVS calibration, it want to disable all opp items, except one with
> voltae 1.0V. (SVS will change the voltage field of that opp item, if the
> corresponding voltage is not 1.0V)
> In this way, SVS can make sure there is no other module, include
> thermal, will change Vproc by DVFS driver.
> After SVS calibration done, SVS will enable those disabled opp items
> back.

But why is this required to be done this way ? Why can't we just update the
voltages without doing this disable/enable dance ?

-- 
viresh

Re: [v4, 7/8] cpufreq: mediatek: add opp notification for SVS support

[Viresh Kumar]

On 18-10-19, 17:03, andrew-sh.cheng wrote:
> On Thu, 2019-10-17 at 12:01 +0530, Viresh Kumar wrote:
> > On 16-10-19, 10:43, andrew-sh.cheng wrote:
> > > This is due to SVS feature need to fix Vproc for calibration.
> > > When SVS calibration, it want to disable all opp items, except one with
> > > voltae 1.0V. (SVS will change the voltage field of that opp item, if the
> > > corresponding voltage is not 1.0V)
> > > In this way, SVS can make sure there is no other module, include
> > > thermal, will change Vproc by DVFS driver.
> > > After SVS calibration done, SVS will enable those disabled opp items
> > > back.
> > 
> > But why is this required to be done this way ? Why can't we just update the
> > voltages without doing this disable/enable dance ?
> > 
> This is because some opp items need voltage larger than 1.0V.
> We cannot update the voltage to 1.0V.
> 
> If we don't disable these opp items, and DVFS policy want to set these
> high frequencies, dvfs driver will set higher voltage to Vproc and SVS
> calibration will be fail.

Okay.

-- 
viresh

Re: [v4, 6/8] PM / OPP: Support adjusting OPP voltages at runtime

[Viresh Kumar]

On 13-08-19, 21:31, Andrew-sh.Cheng wrote:
> From: Stephen Boyd <sboyd@codeaurora.org>
> 
> On some SoCs the Adaptive Voltage Scaling (AVS) technique is
> employed to optimize the operating voltage of a device. At a
> given frequency, the hardware monitors dynamic factors and either
> makes a suggestion for how much to adjust a voltage for the
> current frequency, or it automatically adjusts the voltage
> without software intervention. Add an API to the OPP library for
> the former case, so that AVS type devices can update the voltages
> for an OPP when the hardware determines the voltage should
> change. The assumption is that drivers like CPUfreq or devfreq
> will register for the OPP notifiers and adjust the voltage
> according to suggestions that AVS makes.
> 
> This patch is devired from [1] submitted by Stephen.
> [1] https://lore.kernel.org/patchwork/patch/599279/
> 
> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
> Signed-off-by: Roger Lu <roger.lu@mediatek.com>
> ---
>  drivers/opp/core.c     | 63 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/pm_opp.h | 11 +++++++++
>  2 files changed, 74 insertions(+)
> 
> diff --git a/drivers/opp/core.c b/drivers/opp/core.c
> index c094d5d20fd7..407a07f29b12 100644
> --- a/drivers/opp/core.c
> +++ b/drivers/opp/core.c
> @@ -2054,6 +2054,69 @@ static int _opp_set_availability(struct device *dev, unsigned long freq,
>  }
>  
>  /**
> + * dev_pm_opp_adjust_voltage() - helper to change the voltage of an OPP
> + * @dev:		device for which we do this operation
> + * @freq:		OPP frequency to adjust voltage of
> + * @u_volt:		new OPP voltage
> + *
> + * Return: -EINVAL for bad pointers, -ENOMEM if no memory available for the
> + * copy operation, returns 0 if no modifcation was done OR modification was
> + * successful.
> + */
> +int dev_pm_opp_adjust_voltage(struct device *dev, unsigned long freq,
> +			      unsigned long u_volt)

Can you please update this to take a triplet instead ? That is what we are
storing in OPP core now a days.

-- 
viresh

Re: [v4, 6/8] PM / OPP: Support adjusting OPP voltages at runtime

[Roger Lu]

Dear Viresh,

Sorry for the late reply.

On Mon, 2019-08-19 at 19:18 +0800, Viresh Kumar wrote:
> On 13-08-19, 21:31, Andrew-sh.Cheng wrote:
> > From: Stephen Boyd <sboyd@codeaurora.org>
> > 
> > On some SoCs the Adaptive Voltage Scaling (AVS) technique is
> > employed to optimize the operating voltage of a device. At a
> > given frequency, the hardware monitors dynamic factors and either
> > makes a suggestion for how much to adjust a voltage for the
> > current frequency, or it automatically adjusts the voltage
> > without software intervention. Add an API to the OPP library for
> > the former case, so that AVS type devices can update the voltages
> > for an OPP when the hardware determines the voltage should
> > change. The assumption is that drivers like CPUfreq or devfreq
> > will register for the OPP notifiers and adjust the voltage
> > according to suggestions that AVS makes.
> > 
> > This patch is devired from [1] submitted by Stephen.
> > [1] https://lore.kernel.org/patchwork/patch/599279/
> > 
> > Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
> > Signed-off-by: Roger Lu <roger.lu@mediatek.com>
> > ---
> >  drivers/opp/core.c     | 63 ++++++++++++++++++++++++++++++++++++++++++++++++++
> >  include/linux/pm_opp.h | 11 +++++++++
> >  2 files changed, 74 insertions(+)
> > 
> > diff --git a/drivers/opp/core.c b/drivers/opp/core.c
> > index c094d5d20fd7..407a07f29b12 100644
> > --- a/drivers/opp/core.c
> > +++ b/drivers/opp/core.c
> > @@ -2054,6 +2054,69 @@ static int _opp_set_availability(struct device *dev, unsigned long freq,
> >  }
> >  
> >  /**
> > + * dev_pm_opp_adjust_voltage() - helper to change the voltage of an OPP
> > + * @dev:		device for which we do this operation
> > + * @freq:		OPP frequency to adjust voltage of
> > + * @u_volt:		new OPP voltage
> > + *
> > + * Return: -EINVAL for bad pointers, -ENOMEM if no memory available for the
> > + * copy operation, returns 0 if no modifcation was done OR modification was
> > + * successful.
> > + */
> > +int dev_pm_opp_adjust_voltage(struct device *dev, unsigned long freq,
> > +			      unsigned long u_volt)
> 
> Can you please update this to take a triplet instead ? That is what we are
> storing in OPP core now a days.

I've studied opp/core.c and still don't know meaning of triplet here.
Could you give me more hints (reference API?) about how to take a
triplet instead? Thanks in advance.

Re: [v4, 6/8] PM / OPP: Support adjusting OPP voltages at runtime

[Viresh Kumar]

On 01-11-19, 16:08, Roger Lu wrote:
> I've studied opp/core.c and still don't know meaning of triplet here.
> Could you give me more hints (reference API?) about how to take a
> triplet instead? Thanks in advance.

I was hoping you to follow this thread :)

https://lore.kernel.org/linux-arm-kernel/20191016145756.16004-2-s.nawrocki@samsung.com/

I already applied this patch to the OPP tree.

-- 
viresh

Re: [v4, 6/8] PM / OPP: Support adjusting OPP voltages at runtime

[Matthias Brugger]

On 13/08/2019 15:31, Andrew-sh.Cheng wrote:
> From: Stephen Boyd <sboyd@codeaurora.org>
> 
> On some SoCs the Adaptive Voltage Scaling (AVS) technique is
> employed to optimize the operating voltage of a device. At a
> given frequency, the hardware monitors dynamic factors and either
> makes a suggestion for how much to adjust a voltage for the
> current frequency, or it automatically adjusts the voltage
> without software intervention. Add an API to the OPP library for
> the former case, so that AVS type devices can update the voltages
> for an OPP when the hardware determines the voltage should
> change. The assumption is that drivers like CPUfreq or devfreq
> will register for the OPP notifiers and adjust the voltage
> according to suggestions that AVS makes.
> 
> This patch is devired from [1] submitted by Stephen.
> [1] https://lore.kernel.org/patchwork/patch/599279/
> 
> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
> Signed-off-by: Roger Lu <roger.lu@mediatek.com>

Nit: your signed-off-by tag is missing.

Regards,
Matthias

> ---
>  drivers/opp/core.c     | 63 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/pm_opp.h | 11 +++++++++
>  2 files changed, 74 insertions(+)
> 
> diff --git a/drivers/opp/core.c b/drivers/opp/core.c
> index c094d5d20fd7..407a07f29b12 100644
> --- a/drivers/opp/core.c
> +++ b/drivers/opp/core.c
> @@ -2054,6 +2054,69 @@ static int _opp_set_availability(struct device *dev, unsigned long freq,
>  }
>  
>  /**
> + * dev_pm_opp_adjust_voltage() - helper to change the voltage of an OPP
> + * @dev:		device for which we do this operation
> + * @freq:		OPP frequency to adjust voltage of
> + * @u_volt:		new OPP voltage
> + *
> + * Return: -EINVAL for bad pointers, -ENOMEM if no memory available for the
> + * copy operation, returns 0 if no modifcation was done OR modification was
> + * successful.
> + */
> +int dev_pm_opp_adjust_voltage(struct device *dev, unsigned long freq,
> +			      unsigned long u_volt)
> +{
> +	struct opp_table *opp_table;
> +	struct dev_pm_opp *tmp_opp, *opp = ERR_PTR(-ENODEV);
> +	int r = 0;
> +
> +	/* Find the opp_table */
> +	opp_table = _find_opp_table(dev);
> +	if (IS_ERR(opp_table)) {
> +		r = PTR_ERR(opp_table);
> +		dev_warn(dev, "%s: Device OPP not found (%d)\n", __func__, r);
> +		return r;
> +	}
> +
> +	mutex_lock(&opp_table->lock);
> +
> +	/* Do we have the frequency? */
> +	list_for_each_entry(tmp_opp, &opp_table->opp_list, node) {
> +		if (tmp_opp->rate == freq) {
> +			opp = tmp_opp;
> +			break;
> +		}
> +	}
> +
> +	if (IS_ERR(opp)) {
> +		r = PTR_ERR(opp);
> +		goto adjust_unlock;
> +	}
> +
> +	/* Is update really needed? */
> +	if (opp->supplies->u_volt == u_volt)
> +		goto adjust_unlock;
> +
> +	opp->supplies->u_volt = u_volt;
> +
> +	dev_pm_opp_get(opp);
> +	mutex_unlock(&opp_table->lock);
> +
> +	/* Notify the voltage change of the OPP */
> +	blocking_notifier_call_chain(&opp_table->head, OPP_EVENT_ADJUST_VOLTAGE,
> +				     opp);
> +
> +	dev_pm_opp_put(opp);
> +	goto adjust_put_table;
> +
> +adjust_unlock:
> +	mutex_unlock(&opp_table->lock);
> +adjust_put_table:
> +	dev_pm_opp_put_opp_table(opp_table);
> +	return r;
> +}
> +
> +/**
>   * dev_pm_opp_enable() - Enable a specific OPP
>   * @dev:	device for which we do this operation
>   * @freq:	OPP frequency to enable
> diff --git a/include/linux/pm_opp.h b/include/linux/pm_opp.h
> index af5021f27cb7..86947d53e8c4 100644
> --- a/include/linux/pm_opp.h
> +++ b/include/linux/pm_opp.h
> @@ -22,6 +22,7 @@ struct opp_table;
>  
>  enum dev_pm_opp_event {
>  	OPP_EVENT_ADD, OPP_EVENT_REMOVE, OPP_EVENT_ENABLE, OPP_EVENT_DISABLE,
> +	OPP_EVENT_ADJUST_VOLTAGE,
>  };
>  
>  /**
> @@ -111,6 +112,9 @@ int dev_pm_opp_add(struct device *dev, unsigned long freq,
>  void dev_pm_opp_remove(struct device *dev, unsigned long freq);
>  void dev_pm_opp_remove_all_dynamic(struct device *dev);
>  
> +int dev_pm_opp_adjust_voltage(struct device *dev, unsigned long freq,
> +			      unsigned long u_volt);
> +
>  int dev_pm_opp_enable(struct device *dev, unsigned long freq);
>  
>  int dev_pm_opp_disable(struct device *dev, unsigned long freq);
> @@ -234,6 +238,13 @@ static inline void dev_pm_opp_remove_all_dynamic(struct device *dev)
>  {
>  }
>  
> +static inline int
> +dev_pm_opp_adjust_voltage(struct device *dev, unsigned long freq,
> +			  unsigned long u_volt)
> +{
> +	return 0;
> +}
> +
>  static inline int dev_pm_opp_enable(struct device *dev, unsigned long freq)
>  {
>  	return 0;
>