[PATCH v2 0/4] fixed mediatek-cpufreq has multi policy concurrency issue

[PATCH v2 0/4] fixed mediatek-cpufreq has multi policy concurrency issue

[Mark Tseng]

For multi cluster SoC, the cpufreq->target_index() is re-enter function
for each policy to change CPU frequency. In the cirtical session must
use glocal mutex lock to avoid get wrong OPP.

Changes since v1:
	  - seperate more patch for detail change.

Mark Tseng (4):
  cpufreq: mediatek: CCI support SoC , the transition_delay set to 10 ms
  cpufreq: mediatek: using global lock avoid race condition
  cpufreq: mediatek: Add CPUFREQ_ASYNC_NOTIFICATION flag
  cpufreq: mediatek: data safety protect

 drivers/cpufreq/mediatek-cpufreq.c | 65 ++++++++++++++++++++++--------
 1 file changed, 49 insertions(+), 16 deletions(-)

-- 
2.45.2

[PATCH v2 1/4] cpufreq: mediatek: CCI support SoC , the transition_delay set to 10 ms

[Mark Tseng]

SoC with CCI architecture should set transition_delay to 10 ms because
cpufreq need to call devfreq notifier in async mode. if delay less than
10 ms, it may get wrong OPP-level in devfreq passive governor.

Signed-off-by: Mark Tseng <chun-jen.tseng@mediatek.com>
---
 drivers/cpufreq/mediatek-cpufreq.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/cpufreq/mediatek-cpufreq.c b/drivers/cpufreq/mediatek-cpufreq.c
index 663f61565cf7..f63183154e9a 100644
--- a/drivers/cpufreq/mediatek-cpufreq.c
+++ b/drivers/cpufreq/mediatek-cpufreq.c
@@ -597,6 +597,9 @@ static int mtk_cpufreq_init(struct cpufreq_policy *policy)
 	policy->driver_data = info;
 	policy->clk = info->cpu_clk;
 
+	if (info->soc_data->ccifreq_supported)
+		policy->transition_delay_us = 10000;
+
 	return 0;
 }
 
-- 
2.45.2

Re: [PATCH v2 1/4] cpufreq: mediatek: CCI support SoC , the transition_delay set to 10 ms

[AngeloGioacchino Del Regno]

Il 08/11/24 07:39, Mark Tseng ha scritto:
> SoC with CCI architecture should set transition_delay to 10 ms because
> cpufreq need to call devfreq notifier in async mode. if delay less than
> 10 ms, it may get wrong OPP-level in devfreq passive governor.
> 

This means that MediaTek SoCs can change their CPU frequency once every
10 milliseconds?!?!?!

I don't think that's really the case.

Besides, are you aware that this will have a *huge* impact on either power
consumption or performance?
We're going from a bunch of microseconds to *multiple* milliseconds here.

Regards,
Angelo

Re: [PATCH v2 1/4] cpufreq: mediatek: CCI support SoC , the transition_delay set to 10 ms

[Chun-Jen Tseng (曾俊仁)]

On Thu, 2024-11-14 at 11:22 +0100, AngeloGioacchino Del Regno wrote:

hi Angelo,

Thanks your review and recommendation.

I will fix this issue on next patch.

BRs,

Mark Tseng

> 
> External email : Please do not click links or open attachments until
> you have verified the sender or the content.
> 
> 
> Il 08/11/24 07:39, Mark Tseng ha scritto:
> > SoC with CCI architecture should set transition_delay to 10 ms
> > because
> > cpufreq need to call devfreq notifier in async mode. if delay less
> > than
> > 10 ms, it may get wrong OPP-level in devfreq passive governor.
> > 
> 
> This means that MediaTek SoCs can change their CPU frequency once
> every
> 10 milliseconds?!?!?!
> 
> I don't think that's really the case.
> 
> Besides, are you aware that this will have a *huge* impact on either
> power
> consumption or performance?
> We're going from a bunch of microseconds to *multiple* milliseconds
> here.
> 
> Regards,
> Angelo
> 

[PATCH v2 2/4] cpufreq: mediatek: using global lock avoid race condition

[Mark Tseng]

In mtk_cpufreq_set_target() is re-enter function but the mutex lock
decalre in mtk_cpu_dvfs_info structure for each policy. It should
change to global variable for critical session avoid race condition
with 2 or more policy.

add mtk_cpufreq_get() replace cpufreq_generic_get() and use global lock
avoid return wrong clock.

Signed-off-by: Mark Tseng <chun-jen.tseng@mediatek.com>
---
 drivers/cpufreq/mediatek-cpufreq.c | 39 ++++++++++++++++++++++--------
 1 file changed, 29 insertions(+), 10 deletions(-)

diff --git a/drivers/cpufreq/mediatek-cpufreq.c b/drivers/cpufreq/mediatek-cpufreq.c
index f63183154e9a..6b3cd2b803bf 100644
--- a/drivers/cpufreq/mediatek-cpufreq.c
+++ b/drivers/cpufreq/mediatek-cpufreq.c
@@ -49,8 +49,6 @@ struct mtk_cpu_dvfs_info {
 	bool need_voltage_tracking;
 	int vproc_on_boot;
 	int pre_vproc;
-	/* Avoid race condition for regulators between notify and policy */
-	struct mutex reg_lock;
 	struct notifier_block opp_nb;
 	unsigned int opp_cpu;
 	unsigned long current_freq;
@@ -59,6 +57,9 @@ struct mtk_cpu_dvfs_info {
 	bool ccifreq_bound;
 };
 
+/* Avoid race condition for regulators between notify and policy */
+static DEFINE_MUTEX(mtk_policy_lock);
+
 static struct platform_device *cpufreq_pdev;
 
 static LIST_HEAD(dvfs_info_list);
@@ -209,12 +210,12 @@ static int mtk_cpufreq_set_target(struct cpufreq_policy *policy,
 	long freq_hz, pre_freq_hz;
 	int vproc, pre_vproc, inter_vproc, target_vproc, ret;
 
+	mutex_lock(&mtk_policy_lock);
+
 	inter_vproc = info->intermediate_voltage;
 
 	pre_freq_hz = clk_get_rate(cpu_clk);
 
-	mutex_lock(&info->reg_lock);
-
 	if (unlikely(info->pre_vproc <= 0))
 		pre_vproc = regulator_get_voltage(info->proc_reg);
 	else
@@ -308,7 +309,7 @@ static int mtk_cpufreq_set_target(struct cpufreq_policy *policy,
 	info->current_freq = freq_hz;
 
 out:
-	mutex_unlock(&info->reg_lock);
+	mutex_unlock(&mtk_policy_lock);
 
 	return ret;
 }
@@ -316,19 +317,20 @@ static int mtk_cpufreq_set_target(struct cpufreq_policy *policy,
 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;
 	struct dev_pm_opp *new_opp;
 	struct mtk_cpu_dvfs_info *info;
 	unsigned long freq, volt;
 	struct cpufreq_policy *policy;
 	int ret = 0;
 
+	mutex_lock(&mtk_policy_lock);
+	opp = data;
 	info = container_of(nb, struct mtk_cpu_dvfs_info, opp_nb);
 
 	if (event == OPP_EVENT_ADJUST_VOLTAGE) {
 		freq = dev_pm_opp_get_freq(opp);
 
-		mutex_lock(&info->reg_lock);
 		if (info->current_freq == freq) {
 			volt = dev_pm_opp_get_voltage(opp);
 			ret = mtk_cpufreq_set_voltage(info, volt);
@@ -336,7 +338,6 @@ static int mtk_cpufreq_opp_notifier(struct notifier_block *nb,
 				dev_err(info->cpu_dev,
 					"failed to scale voltage: %d\n", ret);
 		}
-		mutex_unlock(&info->reg_lock);
 	} else if (event == OPP_EVENT_DISABLE) {
 		freq = dev_pm_opp_get_freq(opp);
 
@@ -361,6 +362,7 @@ static int mtk_cpufreq_opp_notifier(struct notifier_block *nb,
 			}
 		}
 	}
+	mutex_unlock(&mtk_policy_lock);
 
 	return notifier_from_errno(ret);
 }
@@ -495,7 +497,6 @@ 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);
 
-	mutex_init(&info->reg_lock);
 	info->current_freq = clk_get_rate(info->cpu_clk);
 
 	info->opp_cpu = cpu;
@@ -610,13 +611,31 @@ static void mtk_cpufreq_exit(struct cpufreq_policy *policy)
 	dev_pm_opp_free_cpufreq_table(info->cpu_dev, &policy->freq_table);
 }
 
+static unsigned int mtk_cpufreq_get(unsigned int cpu)
+{
+	struct mtk_cpu_dvfs_info *info;
+	unsigned long current_freq;
+
+	mutex_lock(&mtk_policy_lock);
+	info = mtk_cpu_dvfs_info_lookup(cpu);
+	if (!info) {
+		mutex_unlock(&mtk_policy_lock);
+		return 0;
+	}
+
+	current_freq = info->current_freq / 1000;
+	mutex_unlock(&mtk_policy_lock);
+
+	return current_freq;
+}
+
 static struct cpufreq_driver mtk_cpufreq_driver = {
 	.flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK |
 		 CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
 		 CPUFREQ_IS_COOLING_DEV,
 	.verify = cpufreq_generic_frequency_table_verify,
 	.target_index = mtk_cpufreq_set_target,
-	.get = cpufreq_generic_get,
+	.get = mtk_cpufreq_get,
 	.init = mtk_cpufreq_init,
 	.exit = mtk_cpufreq_exit,
 	.register_em = cpufreq_register_em_with_opp,
-- 
2.45.2

[PATCH v2 3/4] cpufreq: mediatek: Add CPUFREQ_ASYNC_NOTIFICATION flag

[Mark Tseng]

Add CPUFREQ_ASYNC_NOTIFICATION flages for cpufreq policy because some of
process will get CPU frequency by cpufreq sysfs node. It may get wrong
frequency then call cpufreq_out_of_sync() to fixed frequency.

Signed-off-by: Mark Tseng <chun-jen.tseng@mediatek.com>
---
 drivers/cpufreq/mediatek-cpufreq.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/cpufreq/mediatek-cpufreq.c b/drivers/cpufreq/mediatek-cpufreq.c
index 6b3cd2b803bf..3369bdd9a348 100644
--- a/drivers/cpufreq/mediatek-cpufreq.c
+++ b/drivers/cpufreq/mediatek-cpufreq.c
@@ -209,12 +209,16 @@ static int mtk_cpufreq_set_target(struct cpufreq_policy *policy,
 	struct dev_pm_opp *opp;
 	long freq_hz, pre_freq_hz;
 	int vproc, pre_vproc, inter_vproc, target_vproc, ret;
+	struct cpufreq_freqs freqs;
 
 	mutex_lock(&mtk_policy_lock);
 
 	inter_vproc = info->intermediate_voltage;
+	pre_freq_hz = policy->cur * 1000;
 
-	pre_freq_hz = clk_get_rate(cpu_clk);
+	freqs.old = policy->cur;
+	freqs.new = freq_table[index].frequency;
+	cpufreq_freq_transition_begin(policy, &freqs);
 
 	if (unlikely(info->pre_vproc <= 0))
 		pre_vproc = regulator_get_voltage(info->proc_reg);
@@ -309,6 +313,7 @@ static int mtk_cpufreq_set_target(struct cpufreq_policy *policy,
 	info->current_freq = freq_hz;
 
 out:
+	cpufreq_freq_transition_end(policy, &freqs, false);
 	mutex_unlock(&mtk_policy_lock);
 
 	return ret;
@@ -632,6 +637,7 @@ static unsigned int mtk_cpufreq_get(unsigned int cpu)
 static struct cpufreq_driver mtk_cpufreq_driver = {
 	.flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK |
 		 CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
+		 CPUFREQ_ASYNC_NOTIFICATION |
 		 CPUFREQ_IS_COOLING_DEV,
 	.verify = cpufreq_generic_frequency_table_verify,
 	.target_index = mtk_cpufreq_set_target,
-- 
2.45.2

[PATCH v2 4/4] cpufreq: mediatek: data safety protect

[Mark Tseng]

get policy data in global lock session avoid get wrong data.

Signed-off-by: Mark Tseng <chun-jen.tseng@mediatek.com>
---
 drivers/cpufreq/mediatek-cpufreq.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/cpufreq/mediatek-cpufreq.c b/drivers/cpufreq/mediatek-cpufreq.c
index 3369bdd9a348..3303b6d72ea7 100644
--- a/drivers/cpufreq/mediatek-cpufreq.c
+++ b/drivers/cpufreq/mediatek-cpufreq.c
@@ -201,11 +201,11 @@ static bool is_ccifreq_ready(struct mtk_cpu_dvfs_info *info)
 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 cpufreq_frequency_table *freq_table;
+	struct clk *cpu_clk;
+	struct clk *armpll;
+	struct mtk_cpu_dvfs_info *info;
+	struct device *cpu_dev;
 	struct dev_pm_opp *opp;
 	long freq_hz, pre_freq_hz;
 	int vproc, pre_vproc, inter_vproc, target_vproc, ret;
@@ -213,6 +213,11 @@ static int mtk_cpufreq_set_target(struct cpufreq_policy *policy,
 
 	mutex_lock(&mtk_policy_lock);
 
+	freq_table = policy->freq_table;
+	cpu_clk = policy->clk;
+	armpll = clk_get_parent(cpu_clk);
+	info = policy->driver_data;
+	cpu_dev = info->cpu_dev;
 	inter_vproc = info->intermediate_voltage;
 	pre_freq_hz = policy->cur * 1000;
 
-- 
2.45.2