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cpufreq: mediatek: Refine mtk_cpufreq_voltage_tracking()
authorJia-Wei Chang <jia-wei.chang@mediatek.com>
Thu, 5 May 2022 11:52:20 +0000 (19:52 +0800)
committerViresh Kumar <viresh.kumar@linaro.org>
Fri, 6 May 2022 04:10:42 +0000 (09:40 +0530)
Because the difference of sram and proc should in a range of min_volt_shift
and max_volt_shift. We need to adjust the sram and proc step by step.

We replace VOLT_TOL (voltage tolerance) with the platform data and update the
logic to determine the voltage boundary and invoking regulator_set_voltage.

- Use 'sram_min_volt' and 'sram_max_volt' to determine the voltage boundary
  of sram regulator.
- Use (sram_min_volt - min_volt_shift) and 'proc_max_volt' to determine the
  voltage boundary of vproc regulator.

Moreover, to prevent infinite loop when tracking voltage, we calculate the
maximum value for each platform data.
We assume min voltage is 0 and tracking target voltage using
min_volt_shift for each iteration.
The retry_max is 3 times of expeted iteration count.

Signed-off-by: Jia-Wei Chang <jia-wei.chang@mediatek.com>
Signed-off-by: Rex-BC Chen <rex-bc.chen@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
drivers/cpufreq/mediatek-cpufreq.c

index 0b6c347..fe205ec 100644 (file)
@@ -8,6 +8,7 @@
 #include <linux/cpu.h>
 #include <linux/cpufreq.h>
 #include <linux/cpumask.h>
+#include <linux/minmax.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/of_platform.h>
@@ -15,8 +16,6 @@
 #include <linux/pm_opp.h>
 #include <linux/regulator/consumer.h>
 
-#define VOLT_TOL               (10000)
-
 struct mtk_cpufreq_platform_data {
        int min_volt_shift;
        int max_volt_shift;
@@ -48,6 +47,7 @@ struct mtk_cpu_dvfs_info {
        bool need_voltage_tracking;
        int pre_vproc;
        const struct mtk_cpufreq_platform_data *soc_data;
+       int vtrack_max;
 };
 
 static struct platform_device *cpufreq_pdev;
@@ -73,6 +73,7 @@ static int mtk_cpufreq_voltage_tracking(struct mtk_cpu_dvfs_info *info,
        struct regulator *proc_reg = info->proc_reg;
        struct regulator *sram_reg = info->sram_reg;
        int pre_vproc, pre_vsram, new_vsram, vsram, vproc, ret;
+       int retry = info->vtrack_max;
 
        pre_vproc = regulator_get_voltage(proc_reg);
        if (pre_vproc < 0) {
@@ -80,91 +81,44 @@ static int mtk_cpufreq_voltage_tracking(struct mtk_cpu_dvfs_info *info,
                        "invalid Vproc value: %d\n", pre_vproc);
                return pre_vproc;
        }
-       /* Vsram should not exceed the maximum allowed voltage of SoC. */
-       new_vsram = min(new_vproc + soc_data->min_volt_shift,
-                       soc_data->sram_max_volt);
-
-       if (pre_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 {
-                       pre_vsram = regulator_get_voltage(sram_reg);
-                       if (pre_vsram < 0) {
-                               dev_err(info->cpu_dev,
-                                       "invalid Vsram value: %d\n", pre_vsram);
-                               return pre_vsram;
-                       }
-                       pre_vproc = regulator_get_voltage(proc_reg);
-                       if (pre_vproc < 0) {
-                               dev_err(info->cpu_dev,
-                                       "invalid Vproc value: %d\n", pre_vproc);
-                               return pre_vproc;
-                       }
-
-                       vsram = min(new_vsram,
-                                   pre_vproc + soc_data->min_volt_shift);
 
-                       if (vsram + VOLT_TOL >= soc_data->sram_max_volt) {
-                               vsram = soc_data->sram_max_volt;
+       pre_vsram = regulator_get_voltage(sram_reg);
+       if (pre_vsram < 0) {
+               dev_err(info->cpu_dev, "invalid Vsram value: %d\n", pre_vsram);
+               return pre_vsram;
+       }
 
-                               /*
-                                * 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);
+       new_vsram = clamp(new_vproc + soc_data->min_volt_shift,
+                         soc_data->sram_min_volt, soc_data->sram_max_volt);
 
-                               vproc = new_vproc;
-                       } else {
-                               ret = regulator_set_voltage(sram_reg, vsram,
-                                                           vsram + VOLT_TOL);
+       do {
+               if (pre_vproc <= new_vproc) {
+                       vsram = clamp(pre_vproc + soc_data->max_volt_shift,
+                                     soc_data->sram_min_volt, new_vsram);
+                       ret = regulator_set_voltage(sram_reg, vsram,
+                                                   soc_data->sram_max_volt);
 
-                               vproc = vsram - soc_data->min_volt_shift;
-                       }
                        if (ret)
                                return ret;
 
+                       if (vsram == soc_data->sram_max_volt ||
+                           new_vsram == soc_data->sram_min_volt)
+                               vproc = new_vproc;
+                       else
+                               vproc = vsram - soc_data->min_volt_shift;
+
                        ret = regulator_set_voltage(proc_reg, vproc,
-                                                   vproc + VOLT_TOL);
+                                                   soc_data->proc_max_volt);
                        if (ret) {
                                regulator_set_voltage(sram_reg, pre_vsram,
-                                                     pre_vsram);
+                                                     soc_data->sram_max_volt);
                                return ret;
                        }
-               } while (vproc < new_vproc || vsram < new_vsram);
-       } else if (pre_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 {
-                       pre_vproc = regulator_get_voltage(proc_reg);
-                       if (pre_vproc < 0) {
-                               dev_err(info->cpu_dev,
-                                       "invalid Vproc value: %d\n", pre_vproc);
-                               return pre_vproc;
-                       }
-                       pre_vsram = regulator_get_voltage(sram_reg);
-                       if (pre_vsram < 0) {
-                               dev_err(info->cpu_dev,
-                                       "invalid Vsram value: %d\n", pre_vsram);
-                               return pre_vsram;
-                       }
-
+               } else if (pre_vproc > new_vproc) {
                        vproc = max(new_vproc,
                                    pre_vsram - soc_data->max_volt_shift);
                        ret = regulator_set_voltage(proc_reg, vproc,
-                                                   vproc + VOLT_TOL);
+                                                   soc_data->proc_max_volt);
                        if (ret)
                                return ret;
 
@@ -174,32 +128,24 @@ static int mtk_cpufreq_voltage_tracking(struct mtk_cpu_dvfs_info *info,
                                vsram = max(new_vsram,
                                            vproc + soc_data->min_volt_shift);
 
-                       if (vsram + VOLT_TOL >= soc_data->sram_max_volt) {
-                               vsram = soc_data->sram_max_volt;
-
-                               /*
-                                * 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);
-                       }
-
+                       ret = regulator_set_voltage(sram_reg, vsram,
+                                                   soc_data->sram_max_volt);
                        if (ret) {
                                regulator_set_voltage(proc_reg, pre_vproc,
-                                                     pre_vproc);
+                                                     soc_data->proc_max_volt);
                                return ret;
                        }
-               } while (vproc > new_vproc + VOLT_TOL ||
-                        vsram > new_vsram + VOLT_TOL);
-       }
+               }
+
+               pre_vproc = vproc;
+               pre_vsram = vsram;
+
+               if (--retry < 0) {
+                       dev_err(info->cpu_dev,
+                               "over loop count, failed to set voltage\n");
+                       return -EINVAL;
+               }
+       } while (vproc != new_vproc || vsram != new_vsram);
 
        return 0;
 }
@@ -261,8 +207,8 @@ static int mtk_cpufreq_set_target(struct cpufreq_policy *policy,
         * 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 (pre_vproc < target_vproc) {
+       target_vproc = max(inter_vproc, vproc);
+       if (pre_vproc <= target_vproc) {
                ret = mtk_cpufreq_set_voltage(info, target_vproc);
                if (ret) {
                        dev_err(cpu_dev,
@@ -417,6 +363,15 @@ static int mtk_cpu_dvfs_info_init(struct mtk_cpu_dvfs_info *info, int cpu)
         */
        info->need_voltage_tracking = (info->sram_reg != NULL);
 
+       /*
+        * We assume min voltage is 0 and tracking target voltage using
+        * min_volt_shift for each iteration.
+        * The vtrack_max is 3 times of expeted iteration count.
+        */
+       info->vtrack_max = 3 * DIV_ROUND_UP(max(info->soc_data->sram_max_volt,
+                                               info->soc_data->proc_max_volt),
+                                           info->soc_data->min_volt_shift);
+
        return 0;
 
 out_disable_inter_clock: