Re: [PATCH V3 2/2] cpufreq: scmi: Register for limit change notifications

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On 2/28/24 17:00, Sibi Sankar wrote:


On 2/28/24 18:54, Lukasz Luba wrote:


On 2/27/24 18:16, Sibi Sankar wrote:
Register for limit change notifications if supported and use the throttled
frequency from the notification to apply HW pressure.

Lukasz,

Thanks for taking time to review the series!


Signed-off-by: Sibi Sankar <quic_sibis@xxxxxxxxxxx>
---

v3:
* Sanitize range_max received from the notifier. [Pierre]
* Update commit message.

  drivers/cpufreq/scmi-cpufreq.c | 29 ++++++++++++++++++++++++++++-
  1 file changed, 28 insertions(+), 1 deletion(-)

diff --git a/drivers/cpufreq/scmi-cpufreq.c b/drivers/cpufreq/scmi-cpufreq.c
index 76a0ddbd9d24..78b87b72962d 100644
--- a/drivers/cpufreq/scmi-cpufreq.c
+++ b/drivers/cpufreq/scmi-cpufreq.c
@@ -25,9 +25,13 @@ struct scmi_data {
      int domain_id;
      int nr_opp;
      struct device *cpu_dev;
+    struct cpufreq_policy *policy;
      cpumask_var_t opp_shared_cpus;
+    struct notifier_block limit_notify_nb;
  };
+const struct scmi_handle *handle;

I've missed this bit here.

+static struct scmi_device *scmi_dev;
  static struct scmi_protocol_handle *ph;
  static const struct scmi_perf_proto_ops *perf_ops;
  static struct cpufreq_driver scmi_cpufreq_driver;
@@ -151,6 +155,20 @@ static struct freq_attr *scmi_cpufreq_hw_attr[] = {
      NULL,
  };
+static int scmi_limit_notify_cb(struct notifier_block *nb, unsigned long event, void *data)
+{
+    struct scmi_data *priv = container_of(nb, struct scmi_data, limit_notify_nb);
+    struct scmi_perf_limits_report *limit_notify = data;
+    struct cpufreq_policy *policy = priv->policy;
+
+    policy->max = clamp(limit_notify->range_max_freq/HZ_PER_KHZ, policy->cpuinfo.min_freq,
+                policy->cpuinfo.max_freq);

Please take the division operation out of this clamp() call, somewhere
above. Currently it 'blurs' these stuff, while it's important convertion
to khz. You can call it e.g.:

limit_freq_khz = limit_notify->range_max_freq / HZ_PER_KHZ;

then use in clamp(limit_freq_khz, ...)

ack


+
+    cpufreq_update_pressure(policy);
+
+    return NOTIFY_OK;
+}
+
  static int scmi_cpufreq_init(struct cpufreq_policy *policy)
  {
      int ret, nr_opp, domain;
@@ -269,6 +287,15 @@ static int scmi_cpufreq_init(struct cpufreq_policy *policy)
          }
      }
+    priv->limit_notify_nb.notifier_call = scmi_limit_notify_cb;
+    ret = handle->notify_ops->devm_event_notifier_register(scmi_dev, SCMI_PROTOCOL_PERF,
+                            SCMI_EVENT_PERFORMANCE_LIMITS_CHANGED,
+                            &domain,
+                            &priv->limit_notify_nb);
+    if (ret)
+        dev_warn(cpu_dev,
+             "failed to register for limits change notifier for domain %d\n", domain);
+
      priv->policy = policy;
      return 0;
@@ -342,8 +369,8 @@ static int scmi_cpufreq_probe(struct scmi_device *sdev)
  {
      int ret;
      struct device *dev = &sdev->dev;
-    const struct scmi_handle *handle;

It should be a compilation error...

+    scmi_dev = sdev;
      handle = sdev->handle;

due to usage here, wasn't it?

Not really, isn't it getting the first initialization here?
Are there any compiler options that I need to turn on to
catch these?

Yes, you're right, my apologies for confusion.
I couldn't apply the series due issues in two patch sets
in your dependency list.

Now when I have been manually applying the changes I spotted it.




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