[PATCH] Revert "cpufreq: mediatek: Refine mtk_cpufreq_voltage_tracking()"

From: Viresh Kumar
Date: Fri Dec 02 2022 - 00:26:21 EST

This reverts commit 6a17b3876bc8303612d7ad59ecf7cbc0db418bcd.

This commit caused regression on Banana Pi R64 (MT7622), revert until
the problem is identified and fixed properly.

Link: https://lore.kernel.org/all/930778a1-5e8b-6df6-3276-42dcdadaf682@xxxxxxxxxxxx/
Cc: v5.19+ <stable@xxxxxxxxxxxxxxx> # v5.19+
Reported-by: Nick <vincent@xxxxxxxxxxxx>
Signed-off-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
---
drivers/cpufreq/mediatek-cpufreq.c | 147 +++++++++++++++++++----------
1 file changed, 96 insertions(+), 51 deletions(-)

diff --git a/drivers/cpufreq/mediatek-cpufreq.c b/drivers/cpufreq/mediatek-cpufreq.c
index 7f2680bc9a0f..4466d0c91a6a 100644
--- a/drivers/cpufreq/mediatek-cpufreq.c
+++ b/drivers/cpufreq/mediatek-cpufreq.c
@@ -8,7 +8,6 @@
#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>
@@ -16,6 +15,8 @@
#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;
@@ -55,7 +56,6 @@ struct mtk_cpu_dvfs_info {
unsigned int opp_cpu;
unsigned long current_freq;
const struct mtk_cpufreq_platform_data *soc_data;
- int vtrack_max;
bool ccifreq_bound;
};

@@ -82,7 +82,6 @@ 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) {
@@ -90,44 +89,91 @@ 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;
+ }

- 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;
- }
+ vsram = min(new_vsram,
+ pre_vproc + soc_data->min_volt_shift);

- new_vsram = clamp(new_vproc + soc_data->min_volt_shift,
- soc_data->sram_min_volt, soc_data->sram_max_volt);
+ if (vsram + VOLT_TOL >= soc_data->sram_max_volt) {
+ vsram = soc_data->sram_max_volt;

- 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);
+ /*
+ * 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);

- if (ret)
- return ret;
-
- if (vsram == soc_data->sram_max_volt ||
- new_vsram == soc_data->sram_min_volt)
vproc = new_vproc;
- else
+ } else {
+ ret = regulator_set_voltage(sram_reg, vsram,
+ vsram + VOLT_TOL);
+
vproc = vsram - soc_data->min_volt_shift;
+ }
+ if (ret)
+ return ret;

ret = regulator_set_voltage(proc_reg, vproc,
- soc_data->proc_max_volt);
+ vproc + VOLT_TOL);
if (ret) {
regulator_set_voltage(sram_reg, pre_vsram,
- soc_data->sram_max_volt);
+ pre_vsram);
return ret;
}
- } else if (pre_vproc > new_vproc) {
+ } 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;
+ }
+
vproc = max(new_vproc,
pre_vsram - soc_data->max_volt_shift);
ret = regulator_set_voltage(proc_reg, vproc,
- soc_data->proc_max_volt);
+ vproc + VOLT_TOL);
if (ret)
return ret;

@@ -137,24 +183,32 @@ static int mtk_cpufreq_voltage_tracking(struct mtk_cpu_dvfs_info *info,
vsram = max(new_vsram,
vproc + soc_data->min_volt_shift);

- ret = regulator_set_voltage(sram_reg, vsram,
- soc_data->sram_max_volt);
+ 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);
+ }
+
if (ret) {
regulator_set_voltage(proc_reg, pre_vproc,
- soc_data->proc_max_volt);
+ pre_vproc);
return ret;
}
- }
-
- 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);
+ } while (vproc > new_vproc + VOLT_TOL ||
+ vsram > new_vsram + VOLT_TOL);
+ }

return 0;
}
@@ -250,8 +304,8 @@ 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 = max(inter_vproc, vproc);
- if (pre_vproc <= target_vproc) {
+ target_vproc = (inter_vproc > vproc) ? inter_vproc : vproc;
+ if (pre_vproc < target_vproc) {
ret = mtk_cpufreq_set_voltage(info, target_vproc);
if (ret) {
dev_err(cpu_dev,
@@ -513,15 +567,6 @@ 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:
--
2.31.1.272.g89b43f80a514