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Message-ID: <5a8f1622-4964-a8e1-f8a1-1dbd38948d45@linaro.org>
Date: Mon, 14 Jun 2021 21:58:57 -0400
From: Thara Gopinath <thara.gopinath@...aro.org>
To: Viresh Kumar <viresh.kumar@...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 6/14/21 6:31 AM, Viresh Kumar wrote:
> 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 ?
stray comment! Will remove it.
>
>> + 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.
You want me to put a comment saying converting frequency in hz to khz ?
>
>> + 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 ?
Get maximum capacity of a cpu.
>
>> + 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..
Yes I should be. But I still need data->cpus to get the policy.
>
>> +}
>> +
>> +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.
I don't understand your comment here. I want to disable irq. call
notify. Start polling. And in polling I want to call notify and if the
thermal event has passed stop polling else continue polling.
>
>> + /**
>> + * 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 ?
Why ? This is the register to read the throttled frequency.
>
>> .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.
Sure.
>
>>
>> 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.
I should considering nothing else is using data->cpus. Yes I will create
a separate init function.
>
>> + 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.
So policy for a cpu can change runtime, right ?
>
>> + 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);
>
--
Warm Regards
Thara (She/Her/Hers)
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