[PATCH v8 0/3] CPUFreq: Add support for opp-sharing cpus

[PATCH v8 0/3] CPUFreq: Add support for opp-sharing cpus

[Nicola Mazzucato]

Hi Viresh,

In this V8 I have addressed your comments:
- correct the goto in patch 1/3
- improve comment in patch 2/3 for dev_pm_opp_get_opp_count()

Many thanks,
Nicola

[v8]
  * Correct "goto" in patch 1/3
  * Improve comment in patch 2/3 for dev_pm_opp_get_opp_count()

This v8 is rebased on v5.11

[v7]
  * Bring back common stuff for CPUs from _init stage to _probe
  * Remove patch "scmi-cpufreq: Move CPU initialisation to probe"

This v7 is based on Linux 5.11-rc6

[v6]
  * Remove deferred probe, not occurring
  * Move common stuff for CPUs from _init stage to _probe

This V6 is rebased on next-20210111

[v5]
  * Rework documentation of opp-shared within OPP node
  * Register EM only for the first CPU within cpumask in driver
  * Add check for nr_opp in driver before registering EM
  * Add comments on both dev_pm_opp_get_opp_count in driver
  * Remove redundant ret=0 in driver

This v5 is rebased on top of:
next-20201208 + Lukasz Luba's patches [1]

[v4]
  * Remove unconditional set of opp_table->shared_opp to exclusive
  * Add implementation for scmi-cpufreq
  * Change subject

These patches are on top of:
next-20201201 + Lukasz Luba's patches (waiting for Rafael) [1]

[v3]
  * Remove proposal for new 'cpu-performance-dependencies' as we instead
    can reuse the opp table.
  * Update documentation for devicetree/bindings/opp
  * Minor changes within opp to support empty opp table
  * Rework the RFC by adding a second proposal

[v2]
  * Fix errors when running make dt_binding_check
  * Improve commit message description for the dt-binding
  * Add RFC for implementation in cpufreq-core and one of its
    drivers.

Nicola Mazzucato (2):
  scmi-cpufreq: Remove deferred probe
  scmi-cpufreq: Get opp_shared_cpus from opp-v2 for EM

Sudeep Holla (1):
  cpufreq: blacklist Arm Vexpress platforms in cpufreq-dt-platdev

 drivers/cpufreq/cpufreq-dt-platdev.c |  2 +
 drivers/cpufreq/scmi-cpufreq.c       | 72 +++++++++++++++++++++-------
 2 files changed, 56 insertions(+), 18 deletions(-)

-- 
2.27.0

[PATCH v8 1/3] scmi-cpufreq: Remove deferred probe

[Nicola Mazzucato]

The current implementation of the scmi_cpufreq_init() function returns
-EPROBE_DEFER when the OPP table is not populated. In practice the
cpufreq core cannot handle this error code.
Therefore, fix the return value and clarify the error message.

Signed-off-by: Nicola Mazzucato <nicola.mazzucato@arm.com>
---
 drivers/cpufreq/scmi-cpufreq.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/cpufreq/scmi-cpufreq.c b/drivers/cpufreq/scmi-cpufreq.c
index 491a0a24fb1e..c0345120a7d5 100644
--- a/drivers/cpufreq/scmi-cpufreq.c
+++ b/drivers/cpufreq/scmi-cpufreq.c
@@ -155,8 +155,10 @@ static int scmi_cpufreq_init(struct cpufreq_policy *policy)
 
 	nr_opp = dev_pm_opp_get_opp_count(cpu_dev);
 	if (nr_opp <= 0) {
-		dev_dbg(cpu_dev, "OPP table is not ready, deferring probe\n");
-		ret = -EPROBE_DEFER;
+		dev_err(cpu_dev, "%s: No OPPs for this device: %d\n",
+			__func__, ret);
+
+		ret = -ENODEV;
 		goto out_free_opp;
 	}
 
-- 
2.27.0

[PATCH v8 2/3] scmi-cpufreq: Get opp_shared_cpus from opp-v2 for EM

[Nicola Mazzucato]

By design, SCMI performance domains define the granularity of
performance controls, they do not describe any underlying hardware
dependencies (although they may match in many cases).

It is therefore possible to have some platforms where hardware may have
the ability to control CPU performance at different granularity and choose
to describe fine-grained performance control through SCMI.

In such situations, the energy model would be provided with inaccurate
information based on controls, while it still needs to know the
performance boundaries.

To restore correct functionality, retrieve information of CPUs under the
same performance domain from operating-points-v2 in DT, and pass it on to
EM.

Signed-off-by: Nicola Mazzucato <nicola.mazzucato@arm.com>
---
 drivers/cpufreq/scmi-cpufreq.c | 74 +++++++++++++++++++++++++---------
 1 file changed, 54 insertions(+), 20 deletions(-)

diff --git a/drivers/cpufreq/scmi-cpufreq.c b/drivers/cpufreq/scmi-cpufreq.c
index c0345120a7d5..5415ed52b53a 100644
--- a/drivers/cpufreq/scmi-cpufreq.c
+++ b/drivers/cpufreq/scmi-cpufreq.c
@@ -126,6 +126,7 @@ static int scmi_cpufreq_init(struct cpufreq_policy *policy)
 	struct scmi_data *priv;
 	struct cpufreq_frequency_table *freq_table;
 	struct em_data_callback em_cb = EM_DATA_CB(scmi_get_cpu_power);
+	cpumask_var_t opp_shared_cpus;
 	bool power_scale_mw;
 
 	cpu_dev = get_cpu_device(policy->cpu);
@@ -134,32 +135,64 @@ static int scmi_cpufreq_init(struct cpufreq_policy *policy)
 		return -ENODEV;
 	}
 
-	ret = handle->perf_ops->device_opps_add(handle, cpu_dev);
-	if (ret) {
-		dev_warn(cpu_dev, "failed to add opps to the device\n");
-		return ret;
-	}
+	if (!zalloc_cpumask_var(&opp_shared_cpus, GFP_KERNEL))
+		ret = -ENOMEM;
 
+	/* Obtain CPUs that share SCMI performance controls */
 	ret = scmi_get_sharing_cpus(cpu_dev, policy->cpus);
 	if (ret) {
 		dev_warn(cpu_dev, "failed to get sharing cpumask\n");
-		return ret;
+		goto out_free_cpumask;
 	}
 
-	ret = dev_pm_opp_set_sharing_cpus(cpu_dev, policy->cpus);
-	if (ret) {
-		dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n",
-			__func__, ret);
-		return ret;
+	/*
+	 * Obtain CPUs that share performance levels.
+	 * The OPP 'sharing cpus' info may come from DT through an empty opp
+	 * table and opp-shared.
+	 */
+	ret = dev_pm_opp_of_get_sharing_cpus(cpu_dev, opp_shared_cpus);
+	if (ret || !cpumask_weight(opp_shared_cpus)) {
+		/*
+		 * Either opp-table is not set or no opp-shared was found.
+		 * Use the CPU mask from SCMI to designate CPUs sharing an OPP
+		 * table.
+		 */
+		cpumask_copy(opp_shared_cpus, policy->cpus);
 	}
 
+	 /*
+	  * A previous CPU may have marked OPPs as shared for a few CPUs, based on
+	  * what OPP core provided. If the current CPU is part of those few, then
+	  * there is no need to add OPPs again.
+	  */
 	nr_opp = dev_pm_opp_get_opp_count(cpu_dev);
 	if (nr_opp <= 0) {
-		dev_err(cpu_dev, "%s: No OPPs for this device: %d\n",
-			__func__, ret);
-
-		ret = -ENODEV;
-		goto out_free_opp;
+		ret = handle->perf_ops->device_opps_add(handle, cpu_dev);
+		if (ret) {
+			dev_warn(cpu_dev, "failed to add opps to the device\n");
+			goto out_free_cpumask;
+		}
+
+		nr_opp = dev_pm_opp_get_opp_count(cpu_dev);
+		if (nr_opp <= 0) {
+			dev_err(cpu_dev, "%s: No OPPs for this device: %d\n",
+				__func__, ret);
+
+			ret = -ENODEV;
+			goto out_free_opp;
+		}
+
+		ret = dev_pm_opp_set_sharing_cpus(cpu_dev, opp_shared_cpus);
+		if (ret) {
+			dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n",
+				__func__, ret);
+
+			goto out_free_opp;
+		}
+
+		power_scale_mw = handle->perf_ops->power_scale_mw_get(handle);
+		em_dev_register_perf_domain(cpu_dev, nr_opp, &em_cb,
+					    opp_shared_cpus, power_scale_mw);
 	}
 
 	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
@@ -192,17 +225,18 @@ static int scmi_cpufreq_init(struct cpufreq_policy *policy)
 	policy->fast_switch_possible =
 		handle->perf_ops->fast_switch_possible(handle, cpu_dev);
 
-	power_scale_mw = handle->perf_ops->power_scale_mw_get(handle);
-	em_dev_register_perf_domain(cpu_dev, nr_opp, &em_cb, policy->cpus,
-				    power_scale_mw);
-
+	free_cpumask_var(opp_shared_cpus);
 	return 0;
 
 out_free_priv:
 	kfree(priv);
+
 out_free_opp:
 	dev_pm_opp_remove_all_dynamic(cpu_dev);
 
+out_free_cpumask:
+	free_cpumask_var(opp_shared_cpus);
+
 	return ret;
 }
 
-- 
2.27.0

[PATCH v8 3/3] cpufreq: blacklist Arm Vexpress platforms in cpufreq-dt-platdev

[Nicola Mazzucato]

From: Sudeep Holla <sudeep.holla@arm.com>

Add "arm,vexpress" to cpufreq-dt-platdev blacklist since the actual
scaling is handled by the firmware cpufreq drivers(scpi, scmi and
vexpress-spc).

Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
---
 drivers/cpufreq/cpufreq-dt-platdev.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/cpufreq/cpufreq-dt-platdev.c b/drivers/cpufreq/cpufreq-dt-platdev.c
index bd2db0188cbb..91e6a0c10dbf 100644
--- a/drivers/cpufreq/cpufreq-dt-platdev.c
+++ b/drivers/cpufreq/cpufreq-dt-platdev.c
@@ -103,6 +103,8 @@ static const struct of_device_id whitelist[] __initconst = {
 static const struct of_device_id blacklist[] __initconst = {
 	{ .compatible = "allwinner,sun50i-h6", },
 
+	{ .compatible = "arm,vexpress", },
+
 	{ .compatible = "calxeda,highbank", },
 	{ .compatible = "calxeda,ecx-2000", },
 
-- 
2.27.0

Re: [PATCH v8 0/3] CPUFreq: Add support for opp-sharing cpus

[Viresh Kumar]

On 18-02-21, 22:23, Nicola Mazzucato wrote:
> Hi Viresh,
> 
> In this V8 I have addressed your comments:
> - correct the goto in patch 1/3
> - improve comment in patch 2/3 for dev_pm_opp_get_opp_count()

LGTM. I will apply them after the merge window is over. Thanks.

-- 
viresh

Re: [PATCH v8 0/3] CPUFreq: Add support for opp-sharing cpus

[Sudeep Holla]

Hi Viresh,

On Fri, Feb 19, 2021 at 09:49:44AM +0530, Viresh Kumar wrote:
> On 18-02-21, 22:23, Nicola Mazzucato wrote:
> > Hi Viresh,
> > 
> > In this V8 I have addressed your comments:
> > - correct the goto in patch 1/3
> > - improve comment in patch 2/3 for dev_pm_opp_get_opp_count()
> 
> LGTM. I will apply them after the merge window is over. Thanks.

I am planning to merge the series on scmi[1] which changes scmi-cpufreq.c
and will conflict with these changes I think. If possible either,

1. Share a branch with these changes that I can merge or
2. I can take patch 1/3 and 2/3 with other scmi changes with your Ack.

I am fine either way, let me know by v5.12-rc1

--
Regards,
Sudeep

[1] https://lore.kernel.org/linux-arm-kernel/20210202221555.41167-1-cristian.marussi@arm.com/

Re: [PATCH v8 0/3] CPUFreq: Add support for opp-sharing cpus

[Viresh Kumar]

On 19-02-21, 19:16, Sudeep Holla wrote:
> Hi Viresh,
> 
> On Fri, Feb 19, 2021 at 09:49:44AM +0530, Viresh Kumar wrote:
> > On 18-02-21, 22:23, Nicola Mazzucato wrote:
> > > Hi Viresh,
> > > 
> > > In this V8 I have addressed your comments:
> > > - correct the goto in patch 1/3
> > > - improve comment in patch 2/3 for dev_pm_opp_get_opp_count()
> > 
> > LGTM. I will apply them after the merge window is over. Thanks.
> 
> I am planning to merge the series on scmi[1] which changes scmi-cpufreq.c
> and will conflict with these changes I think. If possible either,
> 
> 1. Share a branch with these changes that I can merge or
> 2. I can take patch 1/3 and 2/3 with other scmi changes with your Ack.
> 
> I am fine either way, let me know by v5.12-rc1

I have applied 3/3, you can take first two and add my Ack.

Acked-by: Viresh Kumar <viresh.kumar@linaro.org>

-- 
viresh

Re: [PATCH v8 0/3] CPUFreq: Add support for opp-sharing cpus

[Sudeep Holla]

On Mon, Feb 22, 2021 at 10:09:04AM +0530, Viresh Kumar wrote:
> On 19-02-21, 19:16, Sudeep Holla wrote:
> > Hi Viresh,
> > 
> > On Fri, Feb 19, 2021 at 09:49:44AM +0530, Viresh Kumar wrote:
> > > On 18-02-21, 22:23, Nicola Mazzucato wrote:
> > > > Hi Viresh,
> > > > 
> > > > In this V8 I have addressed your comments:
> > > > - correct the goto in patch 1/3
> > > > - improve comment in patch 2/3 for dev_pm_opp_get_opp_count()
> > > 
> > > LGTM. I will apply them after the merge window is over. Thanks.
> > 
> > I am planning to merge the series on scmi[1] which changes scmi-cpufreq.c
> > and will conflict with these changes I think. If possible either,
> > 
> > 1. Share a branch with these changes that I can merge or
> > 2. I can take patch 1/3 and 2/3 with other scmi changes with your Ack.
> > 
> > I am fine either way, let me know by v5.12-rc1
> 
> I have applied 3/3, you can take first two and add my Ack.
> 
> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
> 

Thanks Viresh, I will pick after v5.12-rc1

-- 
Regards,
Sudeep

Re: [PATCH v8 0/3] CPUFreq: Add support for opp-sharing cpus

[Sudeep Holla]

On Thu, 18 Feb 2021 22:23:23 +0000, Nicola Mazzucato wrote:
> In this V8 I have addressed your comments:
> - correct the goto in patch 1/3
> - improve comment in patch 2/3 for dev_pm_opp_get_opp_count()
> 
> Many thanks,
> Nicola
> 
> [...]


Applied the first 2 patches to sudeep.holla/linux (for-next/scmi), thanks!

[1/3] scmi-cpufreq: Remove deferred probe
      https://git.kernel.org/sudeep.holla/c/2a3390d53b
[2/3] scmi-cpufreq: Get opp_shared_cpus from opp-v2 for EM
      https://git.kernel.org/sudeep.holla/c/dac7a57d2a

--

Regards,
Sudeep

Re: [PATCH v8 0/3] CPUFreq: Add support for opp-sharing cpus

[Sudeep Holla]

On Thu, 18 Feb 2021 22:23:23 +0000, Nicola Mazzucato wrote:
> In this V8 I have addressed your comments:
> - correct the goto in patch 1/3
> - improve comment in patch 2/3 for dev_pm_opp_get_opp_count()
> 
> Many thanks,
> Nicola
> 
> [...]

(New commit info after rebase to v5.12-rc2 for obvious reasons)
Applied to sudeep.holla/linux (for-next/scmi), thanks!

[1/3] scmi-cpufreq: Remove deferred probe
https://git.kernel.org/sudeep.holla/c/71a37cd6a5
[2/3] scmi-cpufreq: Get opp_shared_cpus from opp-v2 for EM
https://git.kernel.org/sudeep.holla/c/80a064dbd5

--
Regards,
Sudeep