linux-kernel - Re: [PATCH v3 1/2] PM / Domains: Add support for 'required-opps' to set default perf state

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Date:   Fri, 16 Jul 2021 14:59:57 +0530
From:   Rajendra Nayak <rnayak@...eaurora.org>
To:     ulf.hansson@...aro.org, bjorn.andersson@...aro.org,
        viresh.kumar@...aro.org
Cc:     linux-pm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        swboyd@...omium.org, rojay@...eaurora.org, stephan@...hold.net
Subject: Re: [PATCH v3 1/2] PM / Domains: Add support for 'required-opps' to
 set default perf state


On 7/16/2021 10:43 AM, Rajendra Nayak wrote:
> Some devics within power domains with performance states do not
> support DVFS, but still need to vote on a default/static state
> while they are active. They can express this using the 'required-opps'
> property in device tree, which points to the phandle of the OPP
> supported by the corresponding power-domains.
> 
> Add support to parse this information from DT and then set the
> specified performance state during attach and drop it on detach.
> Also drop/set as part of runtime suspend/resume callbacks.
> 
> Signed-off-by: Rajendra Nayak <rnayak@...eaurora.org>
> ---
>   drivers/base/power/domain.c | 29 ++++++++++++++++++++++++++++-
>   include/linux/pm_domain.h   |  1 +
>   2 files changed, 29 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index a934c67..eef5507 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -917,6 +917,10 @@ static int genpd_runtime_suspend(struct device *dev)
>   	if (irq_safe_dev_in_no_sleep_domain(dev, genpd))
>   		return 0;
>   
> +	/* Drop the default performance state */
> +	if (dev_gpd_data(dev)->default_pstate)
> +		dev_pm_genpd_set_performance_state(dev, 0);
> +
>   	genpd_lock(genpd);
>   	gpd_data->rpm_pstate = genpd_drop_performance_state(dev);
>   	genpd_power_off(genpd, true, 0);
> @@ -937,6 +941,7 @@ static int genpd_runtime_resume(struct device *dev)
>   {
>   	struct generic_pm_domain *genpd;
>   	struct generic_pm_domain_data *gpd_data = dev_gpd_data(dev);
> +	unsigned int default_pstate = gpd_data->default_pstate;
>   	struct gpd_timing_data *td = &gpd_data->td;
>   	bool runtime_pm = pm_runtime_enabled(dev);
>   	ktime_t time_start;
> @@ -968,6 +973,9 @@ static int genpd_runtime_resume(struct device *dev)
>   	if (ret)
>   		return ret;
>   
> +	/* Set the default performance state */
> +	if (default_pstate)
> +		dev_pm_genpd_set_performance_state(dev, default_pstate);
>    out:
>   	/* Measure resume latency. */
>   	time_start = 0;
> @@ -1000,6 +1008,8 @@ static int genpd_runtime_resume(struct device *dev)
>   	genpd_stop_dev(genpd, dev);
>   err_poweroff:
>   	if (!pm_runtime_is_irq_safe(dev) || genpd_is_irq_safe(genpd)) {
> +		if (default_pstate)
> +			dev_pm_genpd_set_performance_state(dev, 0);
>   		genpd_lock(genpd);
>   		gpd_data->rpm_pstate = genpd_drop_performance_state(dev);
>   		genpd_power_off(genpd, true, 0);
> @@ -2598,6 +2608,12 @@ static void genpd_dev_pm_detach(struct device *dev, bool power_off)
>   
>   	dev_dbg(dev, "removing from PM domain %s\n", pd->name);
>   
> +	/* Drop the default performance state */
> +	if (dev_gpd_data(dev)->default_pstate) {
> +		dev_pm_genpd_set_performance_state(dev, 0);
> +		dev_gpd_data(dev)->default_pstate = 0;
> +	}
> +
>   	for (i = 1; i < GENPD_RETRY_MAX_MS; i <<= 1) {
>   		ret = genpd_remove_device(pd, dev);
>   		if (ret != -EAGAIN)
> @@ -2635,9 +2651,10 @@ static void genpd_dev_pm_sync(struct device *dev)
>   static int __genpd_dev_pm_attach(struct device *dev, struct device *base_dev,
>   				 unsigned int index, bool power_on)
>   {
> +	struct device_node *np;
>   	struct of_phandle_args pd_args;
>   	struct generic_pm_domain *pd;
> -	int ret;
> +	int ret, pstate;
>   
>   	ret = of_parse_phandle_with_args(dev->of_node, "power-domains",
>   				"#power-domain-cells", index, &pd_args);
> @@ -2678,6 +2695,16 @@ static int __genpd_dev_pm_attach(struct device *dev, struct device *base_dev,
>   	if (ret)
>   		genpd_remove_device(pd, dev);
>   
> +	/* Set the default performance state */
> +	np = base_dev->of_node;
> +	if (of_parse_phandle(np, "required-opps", index)) {
> +		pstate = of_get_required_opp_performance_state(np, index);
> +		if (pstate > 0) {
> +			dev_pm_genpd_set_performance_state(dev, pstate);
> +			dev_gpd_data(dev)->default_pstate = pstate;
> +		}
> +	}

I realized this needs better error handling after I sent it out,
I'll fix and respin.

> +
>   	return ret ? -EPROBE_DEFER : 1;
>   }
>   
> diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
> index 21a0577..67017c9 100644
> --- a/include/linux/pm_domain.h
> +++ b/include/linux/pm_domain.h
> @@ -198,6 +198,7 @@ struct generic_pm_domain_data {
>   	struct notifier_block *power_nb;
>   	int cpu;
>   	unsigned int performance_state;
> +	unsigned int default_pstate;
>   	unsigned int rpm_pstate;
>   	ktime_t	next_wakeup;
>   	void *data;
> 

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