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Message-ID: <CALx668X8fB_annmjL+ga7=fmY596HC0-nr+x6r2p0=aaCUJ3-Q@mail.gmail.com>
Date: Thu, 2 Jul 2015 09:31:59 +0800
From: Pi-Cheng Chen <pi-cheng.chen@...aro.org>
To: Alexey Klimov <klimov.linux@...il.com>
Cc: Viresh Kumar <viresh.kumar@...aro.org>,
Michael Turquette <mturquette@...libre.com>,
Matthias Brugger <matthias.bgg@...il.com>,
Mark Rutland <mark.rutland@....com>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
Linaro Kernel Mailman List <linaro-kernel@...ts.linaro.org>,
"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
linux-mediatek@...ts.infradead.org,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v5 2/2] cpufreq: mediatek: Add MT8173 cpufreq driver
Hi Alexey,
On Thu, Jul 2, 2015 at 5:24 AM, Alexey Klimov <klimov.linux@...il.com> wrote:
> Hi Pi-Cheng,
>
> On Wed, Jul 1, 2015 at 5:16 AM, Pi-Cheng Chen <pi-cheng.chen@...aro.org> wrote:
>> This patch implements MT8173 cpufreq driver.
>>
>> Signed-off-by: Pi-Cheng Chen <pi-cheng.chen@...aro.org>
>> ---
>> drivers/cpufreq/Kconfig.arm | 7 +
>> drivers/cpufreq/Makefile | 1 +
>> drivers/cpufreq/mt8173-cpufreq.c | 520 +++++++++++++++++++++++++++++++++++++++
>> 3 files changed, 528 insertions(+)
>> create mode 100644 drivers/cpufreq/mt8173-cpufreq.c
>>
>> diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
>> index 611cb09..2a305c0 100644
>> --- a/drivers/cpufreq/Kconfig.arm
>> +++ b/drivers/cpufreq/Kconfig.arm
>> @@ -141,6 +141,13 @@ config ARM_KIRKWOOD_CPUFREQ
>> This adds the CPUFreq driver for Marvell Kirkwood
>> SoCs.
>>
>> +config ARM_MT8173_CPUFREQ
>> + bool "Mediatek MT8173 CPUFreq support"
>> + depends on ARCH_MEDIATEK && REGULATOR
>> + select PM_OPP
>> + help
>> + This adds the CPUFreq driver support for Mediatek MT8173 SoC.
>> +
>> config ARM_OMAP2PLUS_CPUFREQ
>> bool "TI OMAP2+"
>> depends on ARCH_OMAP2PLUS
>> diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
>> index cdce92a..97f9a9b 100644
>> --- a/drivers/cpufreq/Makefile
>> +++ b/drivers/cpufreq/Makefile
>> @@ -63,6 +63,7 @@ obj-$(CONFIG_ARM_HISI_ACPU_CPUFREQ) += hisi-acpu-cpufreq.o
>> obj-$(CONFIG_ARM_IMX6Q_CPUFREQ) += imx6q-cpufreq.o
>> obj-$(CONFIG_ARM_INTEGRATOR) += integrator-cpufreq.o
>> obj-$(CONFIG_ARM_KIRKWOOD_CPUFREQ) += kirkwood-cpufreq.o
>> +obj-$(CONFIG_ARM_MT8173_CPUFREQ) += mt8173-cpufreq.o
>> obj-$(CONFIG_ARM_OMAP2PLUS_CPUFREQ) += omap-cpufreq.o
>> obj-$(CONFIG_ARM_PXA2xx_CPUFREQ) += pxa2xx-cpufreq.o
>> obj-$(CONFIG_PXA3xx) += pxa3xx-cpufreq.o
>> diff --git a/drivers/cpufreq/mt8173-cpufreq.c b/drivers/cpufreq/mt8173-cpufreq.c
>> new file mode 100644
>> index 0000000..6284e67
>> --- /dev/null
>> +++ b/drivers/cpufreq/mt8173-cpufreq.c
>> @@ -0,0 +1,520 @@
>> +/*
>> + * Copyright (c) 2015 Linaro Ltd.
>> + * Author: Pi-Cheng Chen <pi-cheng.chen@...aro.org>
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License version 2 as
>> + * published by the Free Software Foundation.
>> + *
>> + * This program is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
>> + * GNU General Public License for more details.
>> + */
>> +
>> +#include <linux/clk.h>
>> +#include <linux/cpu.h>
>> +#include <linux/cpu_cooling.h>
>> +#include <linux/cpufreq.h>
>> +#include <linux/cpumask.h>
>> +#include <linux/of.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/pm_opp.h>
>> +#include <linux/regulator/consumer.h>
>> +#include <linux/slab.h>
>> +#include <linux/thermal.h>
>> +
>> +#define MIN_VOLT_SHIFT (100000)
>> +#define MAX_VOLT_SHIFT (200000)
>> +#define MAX_VOLT_LIMIT (1150000)
>> +#define VOLT_TOL (10000)
>> +
>> +/*
>> + * The struct mtk_cpu_dvfs_info holds necessary information for doing CPU DVFS
>> + * on each CPU power/clock domain of Mediatek SoCs. Each CPU cluster in
>> + * Mediatek SoCs has two voltage inputs, Vproc and Vsram. In some cases the two
>> + * voltage inputs need to be controlled under a hardware limitation:
>> + * 100mV < Vsram - Vproc < 200mV
>> + *
>> + * When scaling the clock frequency of a CPU clock domain, the clock source
>> + * needs to be switched to another stable PLL clock temporarily until
>> + * the original PLL becomes stable at target frequency.
>> + */
>> +struct mtk_cpu_dvfs_info {
>> + struct device *cpu_dev;
>> + struct regulator *proc_reg;
>> + struct regulator *sram_reg;
>> + struct clk *cpu_clk;
>> + struct clk *inter_clk;
>> + struct thermal_cooling_device *cdev;
>> + int intermediate_voltage;
>> + bool need_voltage_trace;
>> +};
>> +
>> +static int mtk_cpufreq_voltage_trace(struct mtk_cpu_dvfs_info *info,
>> + int new_vproc)
>> +{
>> + struct regulator *proc_reg = info->proc_reg;
>> + struct regulator *sram_reg = info->sram_reg;
>> + int old_vproc, old_vsram, new_vsram, vsram, vproc, ret;
>> +
>> + old_vproc = regulator_get_voltage(proc_reg);
>> + old_vsram = regulator_get_voltage(sram_reg);
>> + /* Vsram should not exceed the maximum allowed voltage of SoC. */
>> + new_vsram = min(new_vproc + MIN_VOLT_SHIFT, MAX_VOLT_LIMIT);
>> +
>> + if (old_vproc < new_vproc) {
>> + /*
>> + * When scaling up voltages, Vsram and Vproc scale up step
>> + * by step. At each step, set Vsram to (Vproc + 200mV) first,
>> + * then set Vproc to (Vsram - 100mV).
>> + * Keep doing it until Vsram and Vproc hit target voltages.
>> + */
>> + do {
>> + old_vsram = regulator_get_voltage(sram_reg);
>> + old_vproc = regulator_get_voltage(proc_reg);
>> +
>> + vsram = min(new_vsram, old_vproc + MAX_VOLT_SHIFT);
>> +
>> + if (vsram + VOLT_TOL >= MAX_VOLT_LIMIT) {
>> + vsram = MAX_VOLT_LIMIT;
>> +
>> + /*
>> + * If the target Vsram hits the maximum voltage,
>> + * try to set the exact voltage value first.
>> + */
>> + ret = regulator_set_voltage(sram_reg, vsram,
>> + vsram);
>> + if (ret)
>> + ret = regulator_set_voltage(sram_reg,
>> + vsram - VOLT_TOL,
>> + vsram);
>> +
>> + vproc = new_vproc;
>> + } else {
>> + ret = regulator_set_voltage(sram_reg, vsram,
>> + vsram + VOLT_TOL);
>> +
>> + vproc = vsram - MIN_VOLT_SHIFT;
>> + }
>> + if (ret)
>> + return ret;
>> +
>> + ret = regulator_set_voltage(proc_reg, vproc,
>> + vproc + VOLT_TOL);
>> + if (ret) {
>> + regulator_set_voltage(sram_reg, old_vsram,
>> + old_vsram);
>> + return ret;
>> + }
>> + } while (vproc < new_vproc || vsram < new_vsram);
>> + } else if (old_vproc > new_vproc) {
>> + /*
>> + * When scaling down voltages, Vsram and Vproc scale down step
>> + * by step. At each step, set Vproc to (Vsram - 200mV) first,
>> + * then set Vproc to (Vproc + 100mV).
>> + * Keep doing it until Vsram and Vproc hit target voltages.
>> + */
>> + do {
>> + old_vproc = regulator_get_voltage(proc_reg);
>> + old_vsram = regulator_get_voltage(sram_reg);
>> +
>> + vproc = max(new_vproc, old_vsram - MAX_VOLT_SHIFT);
>> + ret = regulator_set_voltage(proc_reg, vproc,
>> + vproc + VOLT_TOL);
>> + if (ret)
>> + return ret;
>> +
>> + if (vproc == new_vproc)
>> + vsram = new_vsram;
>> + else
>> + vsram = max(new_vsram, vproc + MIN_VOLT_SHIFT);
>> +
>> + if (vsram + VOLT_TOL >= MAX_VOLT_LIMIT) {
>> + vsram = MAX_VOLT_LIMIT;
>> +
>> + /*
>> + * If the target Vsram hits the maximum voltage,
>> + * try to set the exact voltage value first.
>> + */
>> + ret = regulator_set_voltage(sram_reg, vsram,
>> + vsram);
>> + if (ret)
>> + ret = regulator_set_voltage(sram_reg,
>> + vsram - VOLT_TOL,
>> + vsram);
>> + } else {
>> + ret = regulator_set_voltage(sram_reg, vsram,
>> + vsram + VOLT_TOL);
>> + }
>> +
>> + if (ret) {
>> + regulator_set_voltage(proc_reg, old_vproc,
>> + old_vproc);
>> + return ret;
>> + }
>> + } while (vproc > new_vproc + VOLT_TOL ||
>> + vsram > new_vsram + VOLT_TOL);
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static int mtk_cpufreq_set_voltage(struct mtk_cpu_dvfs_info *info, int vproc)
>> +{
>> + if (info->need_voltage_trace)
>> + return mtk_cpufreq_voltage_trace(info, vproc);
>> + else
>> + return regulator_set_voltage(info->proc_reg, vproc,
>> + vproc + VOLT_TOL);
>> +}
>> +
>> +static int mtk_cpufreq_set_target(struct cpufreq_policy *policy,
>> + unsigned int index)
>> +{
>> + struct cpufreq_frequency_table *freq_table = policy->freq_table;
>> + struct clk *cpu_clk = policy->clk;
>> + struct clk *armpll = clk_get_parent(cpu_clk);
>> + struct mtk_cpu_dvfs_info *info = policy->driver_data;
>> + struct device *cpu_dev = info->cpu_dev;
>> + struct dev_pm_opp *opp;
>> + long freq_hz, old_freq_hz;
>> + int vproc, old_vproc, inter_vproc, target_vproc, ret;
>> +
>> + inter_vproc = info->intermediate_voltage;
>> +
>> + old_freq_hz = clk_get_rate(cpu_clk);
>> + old_vproc = regulator_get_voltage(info->proc_reg);
>> +
>> + freq_hz = freq_table[index].frequency * 1000;
>> +
>> + rcu_read_lock();
>> + opp = dev_pm_opp_find_freq_ceil(cpu_dev, &freq_hz);
>> + if (IS_ERR(opp)) {
>> + rcu_read_unlock();
>> + pr_err("cpu%d: failed to find OPP for %ld\n",
>> + policy->cpu, freq_hz);
>> + return PTR_ERR(opp);
>> + }
>> + vproc = dev_pm_opp_get_voltage(opp);
>> + rcu_read_unlock();
>> +
>> + /*
>> + * If the new voltage or the intermediate voltage is higher than the
>> + * current voltage, scale up voltage first.
>> + */
>> + target_vproc = (inter_vproc > vproc) ? inter_vproc : vproc;
>> + if (old_vproc < target_vproc) {
>> + ret = mtk_cpufreq_set_voltage(info, target_vproc);
>> + if (ret) {
>> + pr_err("cpu%d: failed to scale up voltage!\n",
>> + policy->cpu);
>> + mtk_cpufreq_set_voltage(info, old_vproc);
>> + return ret;
>> + }
>> + }
>> +
>> + /* Reparent the CPU clock to intermediate clock. */
>> + ret = clk_set_parent(cpu_clk, info->inter_clk);
>> + if (ret) {
>> + pr_err("cpu%d: failed to re-parent cpu clock!\n",
>> + policy->cpu);
>> + mtk_cpufreq_set_voltage(info, old_vproc);
>> + WARN_ON(1);
>> + return ret;
>> + }
>> +
>> + /* Set the original PLL to target rate. */
>> + ret = clk_set_rate(armpll, freq_hz);
>> + if (ret) {
>> + pr_err("cpu%d: failed to scale cpu clock rate!\n",
>> + policy->cpu);
>> + clk_set_parent(cpu_clk, armpll);
>> + mtk_cpufreq_set_voltage(info, old_vproc);
>> + return ret;
>> + }
>> +
>> + /* Set parent of CPU clock back to the original PLL. */
>> + ret = clk_set_parent(cpu_clk, armpll);
>> + if (ret) {
>> + pr_err("cpu%d: failed to re-parent cpu clock!\n",
>> + policy->cpu);
>> + mtk_cpufreq_set_voltage(info, inter_vproc);
>> + WARN_ON(1);
>> + return ret;
>> + }
>> +
>> + /*
>> + * If the new voltage is lower than the intermediate voltage or the
>> + * original voltage, scale down to the new voltage.
>> + */
>> + if (vproc < inter_vproc || vproc < old_vproc) {
>> + ret = mtk_cpufreq_set_voltage(info, vproc);
>> + if (ret) {
>> + pr_err("cpu%d: failed to scale down voltage!\n",
>> + policy->cpu);
>> + clk_set_parent(cpu_clk, info->inter_clk);
>> + clk_set_rate(armpll, old_freq_hz);
>> + clk_set_parent(cpu_clk, armpll);
>> + return ret;
>> + }
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static void mtk_cpufreq_ready(struct cpufreq_policy *policy)
>> +{
>> + struct mtk_cpu_dvfs_info *info = policy->driver_data;
>> + struct device_node *np = of_node_get(info->cpu_dev->of_node);
>> +
>> + if (WARN_ON(!np))
>> + return;
>> +
>> + if (of_find_property(np, "#cooling-cells", NULL)) {
>> + info->cdev = of_cpufreq_cooling_register(np,
>> + policy->related_cpus);
>> +
>> + if (IS_ERR(info->cdev)) {
>> + dev_err(info->cpu_dev,
>> + "running cpufreq without cooling device: %ld\n",
>> + PTR_ERR(info->cdev));
>> +
>> + info->cdev = NULL;
>> + }
>> + }
>> +
>> + of_node_put(np);
>> +}
>> +
>> +static int mtk_cpu_dvfs_info_init(struct mtk_cpu_dvfs_info *info, int cpu)
>> +{
>> + struct device *cpu_dev;
>> + struct regulator *proc_reg = ERR_PTR(-ENODEV);
>> + struct regulator *sram_reg = ERR_PTR(-ENODEV);
>> + struct clk *cpu_clk = ERR_PTR(-ENODEV);
>> + struct clk *inter_clk = ERR_PTR(-ENODEV);
>> + struct dev_pm_opp *opp;
>> + unsigned long rate;
>> + int ret;
>> +
>> + cpu_dev = get_cpu_device(cpu);
>> + if (!cpu_dev) {
>> + pr_err("failed to get cpu%d device\n", cpu);
>> + return -ENODEV;
>> + }
>> +
>> + ret = of_init_opp_table(cpu_dev);
>> + if (ret) {
>> + pr_warn("no OPP table for cpu%d\n", cpu);
>> + return ret;
>> + }
>> +
>> + cpu_clk = clk_get(cpu_dev, "cpu");
>> + if (IS_ERR(cpu_clk)) {
>> + if (PTR_ERR(cpu_clk) == -EPROBE_DEFER)
>> + pr_warn("cpu clk for cpu%d not ready, retry.\n", cpu);
>> + else
>> + pr_err("failed to get cpu clk for cpu%d\n", cpu);
>> +
>> + ret = PTR_ERR(cpu_clk);
>> + goto out_free_opp_table;
>> + }
>> +
>> + inter_clk = clk_get(cpu_dev, "intermediate");
>> + if (IS_ERR(inter_clk)) {
>> + if (PTR_ERR(inter_clk) == -EPROBE_DEFER)
>> + pr_warn("intermediate clk for cpu%d not ready, retry.\n",
>> + cpu);
>> + else
>> + pr_err("failed to get intermediate clk for cpu%d\n",
>> + cpu);
>> +
>> + ret = PTR_ERR(inter_clk);
>> + goto out_free_resources;
>> + }
>> +
>> + proc_reg = regulator_get_exclusive(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",
>> + cpu);
>> + else
>> + pr_err("failed to get proc regulator for cpu%d\n",
>> + cpu);
>> +
>> + ret = PTR_ERR(proc_reg);
>> + goto out_free_resources;
>> + }
>> +
>> + /* Both presence and absence of sram regulator are valid cases. */
>> + sram_reg = regulator_get_exclusive(cpu_dev, "sram");
>> +
>> + /* Search a safe voltage for intermediate frequency. */
>> + rate = clk_get_rate(inter_clk);
>> + rcu_read_lock();
>> + 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_resources;
>> + }
>
> Could you please check this error path? Probably you missed
> rcu_read_unlock() here.
Yes. rcu_read_unlock is missed here. I will add it.
Thanks for your reviewing.
Best Regards,
Pi-Cheng
>
>> + info->intermediate_voltage = dev_pm_opp_get_voltage(opp);
>> + rcu_read_unlock();
>> +
>> + 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;
>> +
>> + /*
>> + * If SRAM regulator is present, software "voltage trace" is needed
>> + * for this CPU power domain.
>> + */
>> + info->need_voltage_trace = !IS_ERR(sram_reg);
>> +
>> + return 0;
>> +
>> +out_free_resources:
>> + if (!IS_ERR(proc_reg))
>> + regulator_put(proc_reg);
>> + if (!IS_ERR(sram_reg))
>> + regulator_put(sram_reg);
>> + if (!IS_ERR(cpu_clk))
>> + clk_put(cpu_clk);
>> + if (!IS_ERR(inter_clk))
>> + clk_put(inter_clk);
>> +
>> +out_free_opp_table:
>> + of_free_opp_table(cpu_dev);
>> +
>> + return ret;
>> +}
>
> <snip>
>
> Best regards,
> Alexey Klimov
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