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SubjectRe: [PATCH v6 2/4] scmi-cpufreq: Move CPU initialisation to probe
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Hi Cristian,

sorry for my late reply.
Thanks for looking into this.

I am preparing a v7 with suggestions proposed by Viresh which, hopefully, should
remove some unclear parts and resolve your comments.
I had left behind some dealloc, so thanks for spotting!

Many thanks,
Nicola

On 1/14/21 4:54 PM, Cristian Marussi wrote:
> Hi Nicola,
>
> a few remarks down below.
>
> On Mon, Jan 11, 2021 at 03:45:22PM +0000, Nicola Mazzucato wrote:
>> Some of the cpu related initialisation can be done at probe stage.
>> This patch moves those initialisations from the ->init callback to the
>> probe stage.
>>
>> This is done in preparation for adding support to retrieve additional
>> information from DT (CPUs sharing v/f lines).
>>
>> Signed-off-by: Nicola Mazzucato <nicola.mazzucato@arm.com>
>> ---
>> drivers/cpufreq/scmi-cpufreq.c | 180 ++++++++++++++++++++++++---------
>> 1 file changed, 135 insertions(+), 45 deletions(-)
>>
>> diff --git a/drivers/cpufreq/scmi-cpufreq.c b/drivers/cpufreq/scmi-cpufreq.c
>> index 15b213ed78fa..4aa97cdc5997 100644
>> --- a/drivers/cpufreq/scmi-cpufreq.c
>> +++ b/drivers/cpufreq/scmi-cpufreq.c
>> @@ -25,6 +25,14 @@ struct scmi_data {
>> struct device *cpu_dev;
>> };
>>
>> +/* Per-CPU storage for runtime management */
>> +struct scmi_cpudata {
>> + cpumask_var_t scmi_shared_cpus;
>> + struct cpufreq_frequency_table *freq_table;
>> +};
>> +
>> +static struct scmi_cpudata *cpudata_table;
>> +
>> static const struct scmi_handle *handle;
>>
>> static unsigned int scmi_cpufreq_get_rate(unsigned int cpu)
>> @@ -120,13 +128,10 @@ scmi_get_cpu_power(unsigned long *power, unsigned long *KHz,
>>
>> static int scmi_cpufreq_init(struct cpufreq_policy *policy)
>> {
>> - int ret, nr_opp;
>> + int ret;
>> unsigned int latency;
>> struct device *cpu_dev;
>> struct scmi_data *priv;
>> - struct cpufreq_frequency_table *freq_table;
>> - struct em_data_callback em_cb = EM_DATA_CB(scmi_get_cpu_power);
>> - bool power_scale_mw;
>>
>> cpu_dev = get_cpu_device(policy->cpu);
>> if (!cpu_dev) {
>> @@ -134,42 +139,19 @@ 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;
>> - }
>> -
>> - ret = scmi_get_sharing_cpus(cpu_dev, policy->cpus);
>> - if (ret) {
>> - dev_warn(cpu_dev, "failed to get sharing cpumask\n");
>> - return ret;
>> - }
>> -
>> - 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;
>> - }
>> -
>> priv = kzalloc(sizeof(*priv), GFP_KERNEL);
>> if (!priv) {
>> ret = -ENOMEM;
>> goto out_free_opp;
>> }
>>
>> - ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table);
>> - if (ret) {
>> - dev_err(cpu_dev, "failed to init cpufreq table: %d\n", ret);
>> - goto out_free_priv;
>> - }
>> + cpumask_copy(policy->cpus, cpudata_table[policy->cpu].scmi_shared_cpus);
>>
>> priv->cpu_dev = cpu_dev;
>> priv->domain_id = handle->perf_ops->device_domain_id(cpu_dev);
>>
>> policy->driver_data = priv;
>> - policy->freq_table = freq_table;
>> + policy->freq_table = cpudata_table[policy->cpu].freq_table;
>>
>> /* SCMI allows DVFS request for any domain from any CPU */
>> policy->dvfs_possible_from_any_cpu = true;
>> @@ -183,23 +165,8 @@ static int scmi_cpufreq_init(struct cpufreq_policy *policy)
>> policy->fast_switch_possible =
>> handle->perf_ops->fast_switch_possible(handle, cpu_dev);
>>
>> - 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_priv;
>> - }
>> -
>> - 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);
>> -
>> return 0;
>>
>> -out_free_priv:
>> - kfree(priv);
>> out_free_opp:
>> dev_pm_opp_remove_all_dynamic(cpu_dev);
>>
>
> My understanding (but I could be wrong given my limited familiarity with
> CPUFREQ ... so bear with me) is that dev_pm_opp_remove_all_dynamic() is
> meant to clean dynamic OPPs added by dev_pm_opp_add() which in turn in
> this driver is folded inside the handle->perf_ops->device_opps_add() call,
> so is not that this call should be added also on the error path inside
> the new scmi_init_device() ? (this was already faulty this way in the
> original code to be honest...if faulty at all :D)
>
> I added a few such invocations down below as rough untested example of
> what I mean.
>
>> @@ -210,7 +177,6 @@ static int scmi_cpufreq_exit(struct cpufreq_policy *policy)
>> {
>> struct scmi_data *priv = policy->driver_data;
>>
>> - dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table);
>> dev_pm_opp_remove_all_dynamic(priv->cpu_dev);
>> kfree(priv);
>>
>> @@ -231,10 +197,102 @@ static struct cpufreq_driver scmi_cpufreq_driver = {
>> .exit = scmi_cpufreq_exit,
>> };
>>
>> +static int scmi_init_cpudata(void)
>> +{
>> + int cpu;
>> + unsigned int ncpus = num_possible_cpus();
>> +
>> + cpudata_table = kzalloc(sizeof(*cpudata_table) * ncpus, GFP_KERNEL);
> Shouldn/t this be a kcalloc() given it's an array allocation, checkpatch
> complains too.
>
>> + if (!cpudata_table)
>> + return -ENOMEM;
>> +
>> + for_each_possible_cpu(cpu) {
>> + if (!zalloc_cpumask_var(&cpudata_table[cpu].scmi_shared_cpus,
>> + GFP_KERNEL))
>> + goto out;
>> + }
>> +
>> + return 0;
>> +
>> +out:
>> + kfree(cpudata_table);
>> + return -ENOMEM;
>> +}
>> +
>> +static int scmi_init_device(const struct scmi_handle *handle, int cpu)
>> +{
>> + struct device *cpu_dev;
>> + int ret, nr_opp;
>> + struct em_data_callback em_cb = EM_DATA_CB(scmi_get_cpu_power);
>> + bool power_scale_mw;
>> + cpumask_var_t scmi_cpus;
>> +
>> + if (!zalloc_cpumask_var(&scmi_cpus, GFP_KERNEL))
>> + return -ENOMEM;
>> +
>> + cpumask_set_cpu(cpu, scmi_cpus);
>> +
>> + cpu_dev = get_cpu_device(cpu);
>> +
>> + ret = scmi_get_sharing_cpus(cpu_dev, scmi_cpus);
>> + if (ret) {
>> + dev_warn(cpu_dev, "failed to get sharing cpumask\n");
>> + goto free_cpumask;
>> + }
>> +
>> + /*
>> + * We get here for each CPU. Add OPPs only on those CPUs for which we
>> + * haven't already done so, or set their OPPs as shared.
>> + */
>> + nr_opp = dev_pm_opp_get_opp_count(cpu_dev);
>> + if (nr_opp <= 0) {
>> + 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 free_cpumask;
>> + }
>> +
>> + ret = dev_pm_opp_set_sharing_cpus(cpu_dev, scmi_cpus);
>> + if (ret) {
>> + dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n",
>> + __func__, ret);
> goto free_dynamic_opps;
>> + }
>> +
>> + 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 free_dynamic_opps;
>> + }
>> +
>> + power_scale_mw = handle->perf_ops->power_scale_mw_get(handle);
>> + em_dev_register_perf_domain(cpu_dev, nr_opp, &em_cb, scmi_cpus,
>> + power_scale_mw);
>> + }
>> +
>> + ret = dev_pm_opp_init_cpufreq_table(cpu_dev,
>> + &cpudata_table[cpu].freq_table);
>> + if (ret) {
>> + dev_err(cpu_dev, "failed to init cpufreq table: %d\n", ret);
> goto free_dynamic_opps;
>> + }
>> +
>> + cpumask_copy(cpudata_table[cpu].scmi_shared_cpus, scmi_cpus);
>> +
> free_dynamic_opps:
> dev_pm_opp_remove_all_dynamic(cpu_dev);
>> +free_cpumask:
>> + free_cpumask_var(scmi_cpus);
>> + return ret;
>> +}
>> +
>> static int scmi_cpufreq_probe(struct scmi_device *sdev)
>> {
>> int ret;
>> struct device *dev = &sdev->dev;
>> + int cpu;
>> + struct device *cpu_dev;
>>
>> handle = sdev->handle;
>>
>> @@ -247,6 +305,24 @@ static int scmi_cpufreq_probe(struct scmi_device *sdev)
>> devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get, NULL);
>> #endif
>>
>> + ret = scmi_init_cpudata();
>> + if (ret) {
>> + pr_err("%s: init cpu data failed\n", __func__);
>> + return ret;
>> + }
>> +
>> + for_each_possible_cpu(cpu) {
>> + cpu_dev = get_cpu_device(cpu);
>> +
>> + ret = scmi_init_device(handle, cpu);
>> + if (ret) {
>> + dev_err(cpu_dev, "%s: init device failed\n",
>> + __func__);
>> +
> goto clean;
>> + }
>> + }
>> +
>> ret = cpufreq_register_driver(&scmi_cpufreq_driver);
>> if (ret) {
>> dev_err(dev, "%s: registering cpufreq failed, err: %d\n",
>
> /* clean any dynamic OPPs already set */
> clean:
> for_each_possible_cpu(cpu) {
> cpu_dev = get_cpu_device(cpu);
>
> dev_pm_opp_remove_all_dynamic(cpu_dev);
> }
>
> return ret;
> }
>
>
> Thanks
>
> Cristian
>
>> @@ -258,6 +334,20 @@ static int scmi_cpufreq_probe(struct scmi_device *sdev)
>>
>> static void scmi_cpufreq_remove(struct scmi_device *sdev)
>> {
>> + int cpu;
>> + struct device *cpu_dev;
>> +
>> + for_each_possible_cpu(cpu) {
>> + cpu_dev = get_cpu_device(cpu);
>> +
>> + dev_pm_opp_free_cpufreq_table(cpu_dev,
>> + &cpudata_table[cpu].freq_table);
>> +
>> + free_cpumask_var(cpudata_table[cpu].scmi_shared_cpus);
>> + }
>> +
>> + kfree(cpudata_table);
>> +
>> cpufreq_unregister_driver(&scmi_cpufreq_driver);
>> }
>>
>> --
>> 2.27.0
>>

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