Date:   Mon, 14 Jun 2021 16:01:41 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Thara Gopinath <thara.gopinath@...aro.org>
Cc:     agross@...nel.org, bjorn.andersson@...aro.org, rui.zhang@...el.com,
        daniel.lezcano@...aro.org, rjw@...ysocki.net, robh+dt@...nel.org,
        linux-arm-msm@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH 3/5] cpufreq: qcom-cpufreq-hw: Add dcvs interrupt support

On 08-06-21, 18:29, Thara Gopinath wrote:
> Add interrupt support to notify the kernel of h/w initiated frequency
> throttling by LMh. Convey this to scheduler via thermal presssure
> interface.
> 
> Signed-off-by: Thara Gopinath <thara.gopinath@...aro.org>
> ---
>  drivers/cpufreq/qcom-cpufreq-hw.c | 100 ++++++++++++++++++++++++++++++
>  1 file changed, 100 insertions(+)
> 
> diff --git a/drivers/cpufreq/qcom-cpufreq-hw.c b/drivers/cpufreq/qcom-cpufreq-hw.c
> index f86859bf76f1..95e17330aa9d 100644
> --- a/drivers/cpufreq/qcom-cpufreq-hw.c
> +++ b/drivers/cpufreq/qcom-cpufreq-hw.c
> @@ -13,6 +13,7 @@
>  #include <linux/of_platform.h>
>  #include <linux/pm_opp.h>
>  #include <linux/slab.h>
> +#include <linux/interrupt.h>
>  
>  #define LUT_MAX_ENTRIES			40U
>  #define LUT_SRC				GENMASK(31, 30)
> @@ -22,10 +23,13 @@
>  #define CLK_HW_DIV			2
>  #define LUT_TURBO_IND			1
>  
> +#define HZ_PER_KHZ			1000
> +
>  struct qcom_cpufreq_soc_data {
>  	u32 reg_enable;
>  	u32 reg_freq_lut;
>  	u32 reg_volt_lut;
> +	u32 reg_current_vote;
>  	u32 reg_perf_state;
>  	u8 lut_row_size;
>  };
> @@ -33,7 +37,11 @@ struct qcom_cpufreq_soc_data {
>  struct qcom_cpufreq_data {
>  	void __iomem *base;
>  	struct resource *res;
> +	struct delayed_work lmh_dcvs_poll_work;
>  	const struct qcom_cpufreq_soc_data *soc_data;
> +	cpumask_var_t cpus;
> +	unsigned long throttled_freq;
> +	int lmh_dcvs_irq;
>  };
>  
>  static unsigned long cpu_hw_rate, xo_rate;
> @@ -251,10 +259,79 @@ static void qcom_get_related_cpus(int index, struct cpumask *m)
>  	}
>  }
>  
> +static inline unsigned long qcom_lmh_vote_to_freq(u32 val)
> +{
> +	return (val & 0x3FF) * 19200;
> +}
> +
> +static void qcom_lmh_dcvs_notify(struct qcom_cpufreq_data *data)
> +{
> +	struct cpufreq_policy policy;
> +	struct dev_pm_opp *opp;
> +	struct device *dev;
> +	unsigned long max_capacity, capacity, freq_hz;
> +	unsigned int val, freq;
> +
> +	val = readl_relaxed(data->base + data->soc_data->reg_current_vote);
> +	freq = qcom_lmh_vote_to_freq(val);
> +	freq_hz = freq * HZ_PER_KHZ;
> +
> +	/* Do I need to calculate ceil and floor ? */

You don't know ?

> +	dev = get_cpu_device(cpumask_first(data->cpus));
> +	opp = dev_pm_opp_find_freq_floor(dev, &freq_hz);
> +	if (IS_ERR(opp) && PTR_ERR(opp) == -ERANGE)
> +		opp = dev_pm_opp_find_freq_ceil(dev, &freq_hz);
> +
> +	data->throttled_freq = freq_hz / HZ_PER_KHZ;
> +

What exactly are we trying to do here ? A comment would be good as
well.

> +	cpufreq_get_policy(&policy, cpumask_first(data->cpus));
> +
> +	/* Update thermal pressure */
> +	max_capacity = arch_scale_cpu_capacity(cpumask_first(data->cpus));

Set capacity of a single CPU from a policy ?

> +	capacity = data->throttled_freq * max_capacity;
> +	capacity /= policy.cpuinfo.max_freq;
> +	/* Don't pass boost capacity to scheduler */
> +	if (capacity > max_capacity)
> +		capacity = max_capacity;
> +	arch_set_thermal_pressure(data->cpus, max_capacity - capacity);

You should really be using policy->cpus instead of allocating
data->cpus..

> +}
> +
> +static void qcom_lmh_dcvs_poll(struct work_struct *work)
> +{
> +	struct qcom_cpufreq_data *data;
> +
> +	data = container_of(work, struct qcom_cpufreq_data, lmh_dcvs_poll_work.work);
> +
> +	qcom_lmh_dcvs_notify(data);

You should really move the below stuff the disable_irq_nosync(), it
will make your life easier.

> +	/**
> +	 * If h/w throttled frequency is higher than what cpufreq has requested for, stop
> +	 * polling and switch back to interrupt mechanism
> +	 */
> +	if (data->throttled_freq >= qcom_cpufreq_hw_get(cpumask_first(data->cpus)))
> +		/* Clear the existing interrupts and enable it back */
> +		enable_irq(data->lmh_dcvs_irq);
> +	else
> +		mod_delayed_work(system_highpri_wq, &data->lmh_dcvs_poll_work,
> +				 msecs_to_jiffies(10));
> +}
> +
> +static irqreturn_t qcom_lmh_dcvs_handle_irq(int irq, void *data)
> +{
> +	struct qcom_cpufreq_data *c_data = data;
> +
> +	/* Disable interrupt and enable polling */
> +	disable_irq_nosync(c_data->lmh_dcvs_irq);
> +	qcom_lmh_dcvs_notify(c_data);
> +	mod_delayed_work(system_highpri_wq, &c_data->lmh_dcvs_poll_work, msecs_to_jiffies(10));
> +
> +	return 0;
> +}
> +
>  static const struct qcom_cpufreq_soc_data qcom_soc_data = {
>  	.reg_enable = 0x0,
>  	.reg_freq_lut = 0x110,
>  	.reg_volt_lut = 0x114,
> +	.reg_current_vote = 0x704,

Should this be a different patch ?

>  	.reg_perf_state = 0x920,
>  	.lut_row_size = 32,
>  };
> @@ -285,6 +362,7 @@ static int qcom_cpufreq_hw_cpu_init(struct cpufreq_policy *policy)
>  	void __iomem *base;
>  	struct qcom_cpufreq_data *data;
>  	int ret, index;
> +	bool lmh_mitigation_enabled = false;

You just overwrite it below, no need to initialize it.

>  
>  	cpu_dev = get_cpu_device(policy->cpu);
>  	if (!cpu_dev) {
> @@ -305,6 +383,8 @@ static int qcom_cpufreq_hw_cpu_init(struct cpufreq_policy *policy)
>  
>  	index = args.args[0];
>  
> +	lmh_mitigation_enabled = of_property_read_bool(pdev->dev.of_node, "qcom,support-lmh");
> +
>  	res = platform_get_resource(pdev, IORESOURCE_MEM, index);
>  	if (!res) {
>  		dev_err(dev, "failed to get mem resource %d\n", index);
> @@ -329,6 +409,11 @@ static int qcom_cpufreq_hw_cpu_init(struct cpufreq_policy *policy)
>  		goto unmap_base;
>  	}
>  
> +	if (!alloc_cpumask_var(&data->cpus, GFP_KERNEL)) {
> +		ret = -ENOMEM;
> +		goto unmap_base;
> +	}
> +
>  	data->soc_data = of_device_get_match_data(&pdev->dev);
>  	data->base = base;
>  	data->res = res;
> @@ -347,6 +432,7 @@ static int qcom_cpufreq_hw_cpu_init(struct cpufreq_policy *policy)
>  		goto error;
>  	}
>  
> +	cpumask_copy(data->cpus, policy->cpus);
>  	policy->driver_data = data;
>  
>  	ret = qcom_cpufreq_hw_read_lut(cpu_dev, policy);
> @@ -370,6 +456,20 @@ static int qcom_cpufreq_hw_cpu_init(struct cpufreq_policy *policy)
>  			dev_warn(cpu_dev, "failed to enable boost: %d\n", ret);
>  	}
>  
> +	if (lmh_mitigation_enabled) {

Shouldn't you move the allocation and setting of data->cpus here ? I
suggest creating a separate routine for all initialization around this
stuff.

> +		data->lmh_dcvs_irq = platform_get_irq(pdev, index);
> +		if (data->lmh_dcvs_irq < 0) {
> +			ret = data->lmh_dcvs_irq;
> +			goto error;
> +		}
> +		ret = devm_request_irq(dev, data->lmh_dcvs_irq, qcom_lmh_dcvs_handle_irq,
> +				       0, "dcvsh-irq", data);

I would rather pass policy as data here.

> +		if (ret) {
> +			dev_err(dev, "Error %d registering irq %x\n", ret, data->lmh_dcvs_irq);
> +			goto error;
> +		}
> +		INIT_DEFERRABLE_WORK(&data->lmh_dcvs_poll_work, qcom_lmh_dcvs_poll);
> +	}
>  	return 0;
>  error:
>  	kfree(data);

-- 
viresh

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