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Message-ID: <20191127083619.etocnhpyyut3hzwq@vireshk-i7>
Date: Wed, 27 Nov 2019 14:06:19 +0530
From: Viresh Kumar <viresh.kumar@...aro.org>
To: "Andrew-sh.Cheng" <andrew-sh.cheng@...iatek.com>
Cc: MyungJoo Ham <myungjoo.ham@...sung.com>,
Kyungmin Park <kyungmin.park@...sung.com>,
Chanwoo Choi <cw00.choi@...sung.com>,
Rob Herring <robh+dt@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Matthias Brugger <matthias.bgg@...il.com>,
"Rafael J. Wysocki" <rjw@...ysocki.net>,
Nishanth Menon <nm@...com>, Stephen Boyd <sboyd@...nel.org>,
linux-pm@...r.kernel.org, devicetree@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org,
linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
srv_heupstream@...iatek.com, fan.chen@...iatek.com
Subject: Re: [v5, PATCH 4/5] cpufreq: mediatek: add opp notification for SVS
support
On 26-11-19, 19:50, Andrew-sh.Cheng wrote:
> diff --git a/drivers/cpufreq/mediatek-cpufreq.c b/drivers/cpufreq/mediatek-cpufreq.c
> index 4b0cc50dd93b..7c37ab31230a 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 */
Will a read-write lock be better suited here for performance reasons ?
> + 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 +297,75 @@ 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);
Do the assignment after all definitions, instead of awkwardly breaking
the line here.
> + 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) {
> + freq = info->opp_freq;
> + opp_item = dev_pm_opp_find_freq_ceil(info->cpu_dev, &freq);
name it new_opp instead of opp_item.
> + if (!IS_ERR(opp_item))
> + dev_pm_opp_put(opp_item);
> + else
> + freq = 0;
> +
What is the purpose of the above code ?
> + /* case of current opp is disabled */
> + if (freq == 0 || freq != info->opp_freq) {
> + // find an enable opp item
Use proper commenting style please.
> + 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);
Why don't you simply call this instead of all the code in the else
block ?
> + 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 +452,21 @@ 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
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