[PATCH 0/6] cpufreq: cleanups

[PATCH 0/6] cpufreq: cleanups

[Viresh Kumar]

Hi Rafael,

I accumulated these while reworking the freq-constraint series and it
would be nice if these can get in before I send the next version of
freq-constraint stuff.

These are mostly cleanups and code consolidation for better management
of code. Compile and boot tested only.

Thanks.

Viresh Kumar (6):
  cpufreq: Remove the redundant !setpolicy check
  cpufreq: Replace few CPUFREQ_CONST_LOOPS checks with has_target()
  cpufreq: Remove the has_target() check from notifier handler
  cpufreq: Use has_target() instead of !setpolicy
  cpufreq: Reuse cpufreq_update_current_freq() in __cpufreq_get()
  cpufreq: Avoid calling cpufreq_verify_current_freq() from
    handle_update()

 drivers/cpufreq/cpufreq.c | 115 +++++++++++++++++---------------------
 1 file changed, 52 insertions(+), 63 deletions(-)

-- 
2.21.0.rc0.269.g1a574e7a288b

[PATCH 1/6] cpufreq: Remove the redundant !setpolicy check

[Viresh Kumar]

cpufreq_start_governor() is only called for !setpolicy case, checking it
again is not required.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 drivers/cpufreq/cpufreq.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 85ff958e01f1..54befd775bd6 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -2153,7 +2153,7 @@ static int cpufreq_start_governor(struct cpufreq_policy *policy)
 
 	pr_debug("%s: for CPU %u\n", __func__, policy->cpu);
 
-	if (cpufreq_driver->get && !cpufreq_driver->setpolicy)
+	if (cpufreq_driver->get)
 		cpufreq_update_current_freq(policy);
 
 	if (policy->governor->start) {
-- 
2.21.0.rc0.269.g1a574e7a288b

[PATCH 2/6] cpufreq: Replace few CPUFREQ_CONST_LOOPS checks with has_target()

[Viresh Kumar]

CPUFREQ_CONST_LOOPS was introduced in a very old commit from pre-2.6
kernel release commit 6a4a93f9c0d5 ("[CPUFREQ] Fix 'out of sync'
issue").

Probably the initial idea was to just avoid these checks for set_policy
type drivers and then things got changed over the years. And it is very
unclear why these checks are there at all.

Replace the CPUFREQ_CONST_LOOPS check with has_target(), which makes
more sense now.

Also remove () around freq comparison statement as they aren't required
and checkpatch also warns for them.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 drivers/cpufreq/cpufreq.c | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 54befd775bd6..e59194c2c613 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -359,12 +359,10 @@ static void cpufreq_notify_transition(struct cpufreq_policy *policy,
 		 * which is not equal to what the cpufreq core thinks is
 		 * "old frequency".
 		 */
-		if (!(cpufreq_driver->flags & CPUFREQ_CONST_LOOPS)) {
-			if (policy->cur && (policy->cur != freqs->old)) {
-				pr_debug("Warning: CPU frequency is %u, cpufreq assumed %u kHz\n",
-					 freqs->old, policy->cur);
-				freqs->old = policy->cur;
-			}
+		if (has_target() && policy->cur && policy->cur != freqs->old) {
+			pr_debug("Warning: CPU frequency is %u, cpufreq assumed %u kHz\n",
+				 freqs->old, policy->cur);
+			freqs->old = policy->cur;
 		}
 
 		srcu_notifier_call_chain(&cpufreq_transition_notifier_list,
@@ -1618,8 +1616,7 @@ static unsigned int __cpufreq_get(struct cpufreq_policy *policy)
 	if (policy->fast_switch_enabled)
 		return ret_freq;
 
-	if (ret_freq && policy->cur &&
-		!(cpufreq_driver->flags & CPUFREQ_CONST_LOOPS)) {
+	if (has_target() && ret_freq && policy->cur) {
 		/* verify no discrepancy between actual and
 					saved value exists */
 		if (unlikely(ret_freq != policy->cur)) {
-- 
2.21.0.rc0.269.g1a574e7a288b

Re: [PATCH 2/6] cpufreq: Replace few CPUFREQ_CONST_LOOPS checks with has_target()

[Rafael J. Wysocki]

On Wed, Jun 19, 2019 at 1:36 PM Viresh Kumar <viresh.kumar@linaro.org> wrote:
>
> CPUFREQ_CONST_LOOPS was introduced in a very old commit from pre-2.6
> kernel release commit 6a4a93f9c0d5 ("[CPUFREQ] Fix 'out of sync'
> issue").
>
> Probably the initial idea was to just avoid these checks for set_policy
> type drivers and then things got changed over the years. And it is very
> unclear why these checks are there at all.
>
> Replace the CPUFREQ_CONST_LOOPS check with has_target(), which makes
> more sense now.
>
> Also remove () around freq comparison statement as they aren't required
> and checkpatch also warns for them.
>
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
> ---
>  drivers/cpufreq/cpufreq.c | 13 +++++--------
>  1 file changed, 5 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index 54befd775bd6..e59194c2c613 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -359,12 +359,10 @@ static void cpufreq_notify_transition(struct cpufreq_policy *policy,
>                  * which is not equal to what the cpufreq core thinks is
>                  * "old frequency".
>                  */
> -               if (!(cpufreq_driver->flags & CPUFREQ_CONST_LOOPS)) {
> -                       if (policy->cur && (policy->cur != freqs->old)) {
> -                               pr_debug("Warning: CPU frequency is %u, cpufreq assumed %u kHz\n",
> -                                        freqs->old, policy->cur);
> -                               freqs->old = policy->cur;
> -                       }
> +               if (has_target() && policy->cur && policy->cur != freqs->old) {
> +                       pr_debug("Warning: CPU frequency is %u, cpufreq assumed %u kHz\n",
> +                                freqs->old, policy->cur);
> +                       freqs->old = policy->cur;

Is cpufreq_notify_transition() ever called if ->setpolicy drivers are in use?

>                 }
>
>                 srcu_notifier_call_chain(&cpufreq_transition_notifier_list,
> @@ -1618,8 +1616,7 @@ static unsigned int __cpufreq_get(struct cpufreq_policy *policy)
>         if (policy->fast_switch_enabled)
>                 return ret_freq;
>
> -       if (ret_freq && policy->cur &&
> -               !(cpufreq_driver->flags & CPUFREQ_CONST_LOOPS)) {
> +       if (has_target() && ret_freq && policy->cur) {
>                 /* verify no discrepancy between actual and
>                                         saved value exists */
>                 if (unlikely(ret_freq != policy->cur)) {
> --
> 2.21.0.rc0.269.g1a574e7a288b
>

Re: [PATCH 2/6] cpufreq: Replace few CPUFREQ_CONST_LOOPS checks with has_target()

[Viresh Kumar]

On 19-06-19, 14:20, Rafael J. Wysocki wrote:
> On Wed, Jun 19, 2019 at 1:36 PM Viresh Kumar <viresh.kumar@linaro.org> wrote:
> > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> > index 54befd775bd6..e59194c2c613 100644
> > --- a/drivers/cpufreq/cpufreq.c
> > +++ b/drivers/cpufreq/cpufreq.c
> > @@ -359,12 +359,10 @@ static void cpufreq_notify_transition(struct cpufreq_policy *policy,
> >                  * which is not equal to what the cpufreq core thinks is
> >                  * "old frequency".
> >                  */
> > -               if (!(cpufreq_driver->flags & CPUFREQ_CONST_LOOPS)) {
> > -                       if (policy->cur && (policy->cur != freqs->old)) {
> > -                               pr_debug("Warning: CPU frequency is %u, cpufreq assumed %u kHz\n",
> > -                                        freqs->old, policy->cur);
> > -                               freqs->old = policy->cur;
> > -                       }
> > +               if (has_target() && policy->cur && policy->cur != freqs->old) {
> > +                       pr_debug("Warning: CPU frequency is %u, cpufreq assumed %u kHz\n",
> > +                                freqs->old, policy->cur);
> > +                       freqs->old = policy->cur;
> 
> Is cpufreq_notify_transition() ever called if ->setpolicy drivers are in use?

I tried to find it, but I couldn't find any driver from where we can
get this called for setpolicy drivers.

-- 
viresh

[PATCH 3/6] cpufreq: Remove the has_target() check from notifier handler

[Viresh Kumar]

cpufreq_notify_transition() is only called for has_target() type driver
and not for set_policy type, and the check is simply redundant. Remove
it.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 drivers/cpufreq/cpufreq.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index e59194c2c613..41ac701e324f 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -359,7 +359,7 @@ static void cpufreq_notify_transition(struct cpufreq_policy *policy,
 		 * which is not equal to what the cpufreq core thinks is
 		 * "old frequency".
 		 */
-		if (has_target() && policy->cur && policy->cur != freqs->old) {
+		if (policy->cur && policy->cur != freqs->old) {
 			pr_debug("Warning: CPU frequency is %u, cpufreq assumed %u kHz\n",
 				 freqs->old, policy->cur);
 			freqs->old = policy->cur;
-- 
2.21.0.rc0.269.g1a574e7a288b

Re: [PATCH 3/6] cpufreq: Remove the has_target() check from notifier handler

[Rafael J. Wysocki]

On Wed, Jun 19, 2019 at 1:35 PM Viresh Kumar <viresh.kumar@linaro.org> wrote:
>
> cpufreq_notify_transition() is only called for has_target() type driver
> and not for set_policy type, and the check is simply redundant. Remove
> it.

Ah, OK

So this patch removes a check introduced by the previous one. :-)

Please merge them together.

> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
> ---
>  drivers/cpufreq/cpufreq.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index e59194c2c613..41ac701e324f 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -359,7 +359,7 @@ static void cpufreq_notify_transition(struct cpufreq_policy *policy,
>                  * which is not equal to what the cpufreq core thinks is
>                  * "old frequency".
>                  */
> -               if (has_target() && policy->cur && policy->cur != freqs->old) {
> +               if (policy->cur && policy->cur != freqs->old) {
>                         pr_debug("Warning: CPU frequency is %u, cpufreq assumed %u kHz\n",
>                                  freqs->old, policy->cur);
>                         freqs->old = policy->cur;
> --
> 2.21.0.rc0.269.g1a574e7a288b
>

Re: [PATCH 3/6] cpufreq: Remove the has_target() check from notifier handler

[Viresh Kumar]

On 19-06-19, 14:25, Rafael J. Wysocki wrote:
> On Wed, Jun 19, 2019 at 1:35 PM Viresh Kumar <viresh.kumar@linaro.org> wrote:
> >
> > cpufreq_notify_transition() is only called for has_target() type driver
> > and not for set_policy type, and the check is simply redundant. Remove
> > it.
> 
> Ah, OK
> 
> So this patch removes a check introduced by the previous one. :-)
> 
> Please merge them together.

It made sense to keep them separate because there are two different
issues I am fixing here. But if that is what you want, I will merge
them.

-- 
viresh

[PATCH 4/6] cpufreq: Use has_target() instead of !setpolicy

[Viresh Kumar]

For code consistency, use has_target() instead of !setpolicy everywhere,
as it is already done at several places. Maybe we should also use
!has_target() for setpolicy case to use only one expression for this
differentiation.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 drivers/cpufreq/cpufreq.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 41ac701e324f..5f5c7a516c74 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -632,7 +632,7 @@ static int cpufreq_parse_policy(char *str_governor,
 }
 
 /**
- * cpufreq_parse_governor - parse a governor string only for !setpolicy
+ * cpufreq_parse_governor - parse a governor string only for has_target()
  */
 static int cpufreq_parse_governor(char *str_governor,
 				  struct cpufreq_policy *policy)
@@ -1301,7 +1301,7 @@ static int cpufreq_online(unsigned int cpu)
 		policy->max = policy->user_policy.max;
 	}
 
-	if (cpufreq_driver->get && !cpufreq_driver->setpolicy) {
+	if (cpufreq_driver->get && has_target()) {
 		policy->cur = cpufreq_driver->get(policy->cpu);
 		if (!policy->cur) {
 			pr_err("%s: ->get() failed\n", __func__);
@@ -2401,7 +2401,7 @@ void cpufreq_update_policy(unsigned int cpu)
 	 * BIOS might change freq behind our back
 	 * -> ask driver for current freq and notify governors about a change
 	 */
-	if (cpufreq_driver->get && !cpufreq_driver->setpolicy &&
+	if (cpufreq_driver->get && has_target() &&
 	    (cpufreq_suspended || WARN_ON(!cpufreq_update_current_freq(policy))))
 		goto unlock;
 
-- 
2.21.0.rc0.269.g1a574e7a288b

Re: [PATCH 4/6] cpufreq: Use has_target() instead of !setpolicy

[Rafael J. Wysocki]

On Wed, Jun 19, 2019 at 1:36 PM Viresh Kumar <viresh.kumar@linaro.org> wrote:
>
> For code consistency, use has_target() instead of !setpolicy everywhere,
> as it is already done at several places.

That's OK

> Maybe we should also use !has_target() for setpolicy case to use only one expression
> for this differentiation.

But I'm not sure what you mean here?

Re: [PATCH 4/6] cpufreq: Use has_target() instead of !setpolicy

[Viresh Kumar]

On 19-06-19, 14:28, Rafael J. Wysocki wrote:
> On Wed, Jun 19, 2019 at 1:36 PM Viresh Kumar <viresh.kumar@linaro.org> wrote:
> >
> > For code consistency, use has_target() instead of !setpolicy everywhere,
> > as it is already done at several places.
> 
> That's OK
> 
> > Maybe we should also use !has_target() for setpolicy case to use only one expression
> > for this differentiation.
> 
> But I'm not sure what you mean here?

At many places in code we are doing tests like:

if (cpufreq_driver->setpolicy) {
        xxx
}

Maybe we can write them as well like:

if (!has_target()) {
        xxx
}

-- 
viresh

[PATCH 5/6] cpufreq: Reuse cpufreq_update_current_freq() in __cpufreq_get()

[Viresh Kumar]

Their implementations are quite similar, lets modify
cpufreq_update_current_freq() a little and use it from __cpufreq_get().

Also rename cpufreq_update_current_freq() to
cpufreq_verify_current_freq(), as that's what it is doing.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 drivers/cpufreq/cpufreq.c | 70 ++++++++++++++++-----------------------
 1 file changed, 28 insertions(+), 42 deletions(-)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 5f5c7a516c74..4556a53fc764 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1547,6 +1547,30 @@ static void cpufreq_out_of_sync(struct cpufreq_policy *policy,
 	cpufreq_freq_transition_end(policy, &freqs, 0);
 }
 
+static unsigned int cpufreq_verify_current_freq(struct cpufreq_policy *policy, bool update)
+{
+	unsigned int new_freq;
+
+	new_freq = cpufreq_driver->get(policy->cpu);
+	if (!new_freq)
+		return 0;
+
+	/*
+	 * If fast frequency switching is used with the given policy, the check
+	 * against policy->cur is pointless, so skip it in that case.
+	 */
+	if (policy->fast_switch_enabled || !has_target())
+		return new_freq;
+
+	if (policy->cur != new_freq) {
+		cpufreq_out_of_sync(policy, new_freq);
+		if (update)
+			schedule_work(&policy->update);
+	}
+
+	return new_freq;
+}
+
 /**
  * cpufreq_quick_get - get the CPU frequency (in kHz) from policy->cur
  * @cpu: CPU number
@@ -1602,30 +1626,10 @@ EXPORT_SYMBOL(cpufreq_quick_get_max);
 
 static unsigned int __cpufreq_get(struct cpufreq_policy *policy)
 {
-	unsigned int ret_freq = 0;
-
 	if (unlikely(policy_is_inactive(policy)))
-		return ret_freq;
-
-	ret_freq = cpufreq_driver->get(policy->cpu);
-
-	/*
-	 * If fast frequency switching is used with the given policy, the check
-	 * against policy->cur is pointless, so skip it in that case too.
-	 */
-	if (policy->fast_switch_enabled)
-		return ret_freq;
-
-	if (has_target() && ret_freq && policy->cur) {
-		/* verify no discrepancy between actual and
-					saved value exists */
-		if (unlikely(ret_freq != policy->cur)) {
-			cpufreq_out_of_sync(policy, ret_freq);
-			schedule_work(&policy->update);
-		}
-	}
+		return 0;
 
-	return ret_freq;
+	return cpufreq_verify_current_freq(policy, true);
 }
 
 /**
@@ -1652,24 +1656,6 @@ unsigned int cpufreq_get(unsigned int cpu)
 }
 EXPORT_SYMBOL(cpufreq_get);
 
-static unsigned int cpufreq_update_current_freq(struct cpufreq_policy *policy)
-{
-	unsigned int new_freq;
-
-	new_freq = cpufreq_driver->get(policy->cpu);
-	if (!new_freq)
-		return 0;
-
-	if (!policy->cur) {
-		pr_debug("cpufreq: Driver did not initialize current freq\n");
-		policy->cur = new_freq;
-	} else if (policy->cur != new_freq && has_target()) {
-		cpufreq_out_of_sync(policy, new_freq);
-	}
-
-	return new_freq;
-}
-
 static struct subsys_interface cpufreq_interface = {
 	.name		= "cpufreq",
 	.subsys		= &cpu_subsys,
@@ -2151,7 +2137,7 @@ static int cpufreq_start_governor(struct cpufreq_policy *policy)
 	pr_debug("%s: for CPU %u\n", __func__, policy->cpu);
 
 	if (cpufreq_driver->get)
-		cpufreq_update_current_freq(policy);
+		cpufreq_verify_current_freq(policy, false);
 
 	if (policy->governor->start) {
 		ret = policy->governor->start(policy);
@@ -2402,7 +2388,7 @@ void cpufreq_update_policy(unsigned int cpu)
 	 * -> ask driver for current freq and notify governors about a change
 	 */
 	if (cpufreq_driver->get && has_target() &&
-	    (cpufreq_suspended || WARN_ON(!cpufreq_update_current_freq(policy))))
+	    (cpufreq_suspended || WARN_ON(!cpufreq_verify_current_freq(policy, false))))
 		goto unlock;
 
 	pr_debug("updating policy for CPU %u\n", cpu);
-- 
2.21.0.rc0.269.g1a574e7a288b

[PATCH 6/6] cpufreq: Avoid calling cpufreq_verify_current_freq() from handle_update()

[Viresh Kumar]

On some occasions cpufreq_verify_current_freq() schedules a work whose
callback is handle_update(), which further calls cpufreq_update_policy()
which may end up calling cpufreq_verify_current_freq() again.

On the other hand, when cpufreq_update_policy() is called from
handle_update(), the pointer to the cpufreq policy is already available
but we still call cpufreq_cpu_acquire() to get it in
cpufreq_update_policy(), which should be avoided as well.

Fix both the issues by creating another helper
reeval_frequency_limits().

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 drivers/cpufreq/cpufreq.c | 26 ++++++++++++++++----------
 1 file changed, 16 insertions(+), 10 deletions(-)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 4556a53fc764..0a73de7aae54 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1115,13 +1115,25 @@ static int cpufreq_add_policy_cpu(struct cpufreq_policy *policy, unsigned int cp
 	return ret;
 }
 
+static void reeval_frequency_limits(struct cpufreq_policy *policy)
+{
+	struct cpufreq_policy new_policy = *policy;
+
+	pr_debug("updating policy for CPU %u\n", policy->cpu);
+
+	new_policy.min = policy->user_policy.min;
+	new_policy.max = policy->user_policy.max;
+
+	cpufreq_set_policy(policy, &new_policy);
+}
+
 static void handle_update(struct work_struct *work)
 {
 	struct cpufreq_policy *policy =
 		container_of(work, struct cpufreq_policy, update);
-	unsigned int cpu = policy->cpu;
-	pr_debug("handle_update for cpu %u called\n", cpu);
-	cpufreq_update_policy(cpu);
+
+	pr_debug("handle_update for cpu %u called\n", policy->cpu);
+	reeval_frequency_limits(policy);
 }
 
 static struct cpufreq_policy *cpufreq_policy_alloc(unsigned int cpu)
@@ -2378,7 +2390,6 @@ int cpufreq_set_policy(struct cpufreq_policy *policy,
 void cpufreq_update_policy(unsigned int cpu)
 {
 	struct cpufreq_policy *policy = cpufreq_cpu_acquire(cpu);
-	struct cpufreq_policy new_policy;
 
 	if (!policy)
 		return;
@@ -2391,12 +2402,7 @@ void cpufreq_update_policy(unsigned int cpu)
 	    (cpufreq_suspended || WARN_ON(!cpufreq_verify_current_freq(policy, false))))
 		goto unlock;
 
-	pr_debug("updating policy for CPU %u\n", cpu);
-	memcpy(&new_policy, policy, sizeof(*policy));
-	new_policy.min = policy->user_policy.min;
-	new_policy.max = policy->user_policy.max;
-
-	cpufreq_set_policy(policy, &new_policy);
+	reeval_frequency_limits(policy);
 
 unlock:
 	cpufreq_cpu_release(policy);
-- 
2.21.0.rc0.269.g1a574e7a288b