Hi Viresh, thanks for looking into this.
Please see below.
On 1/12/21 11:20 AM, Viresh Kumar wrote:
> On 11-01-21, 15:45, Nicola Mazzucato wrote:
>> 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.mazzuc...@arm.com>
>> ---
>> drivers/cpufreq/scmi-cpufreq.c | 22 ++++++++++++++++++++--
>> 1 file changed, 20 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/cpufreq/scmi-cpufreq.c b/drivers/cpufreq/scmi-cpufreq.c
>> index 4aa97cdc5997..ff6ba6fab58b 100644
>> --- a/drivers/cpufreq/scmi-cpufreq.c
>> +++ b/drivers/cpufreq/scmi-cpufreq.c
>> @@ -226,9 +226,12 @@ static int scmi_init_device(const struct scmi_handle
>> *handle, int cpu)
>> struct em_data_callback em_cb = EM_DATA_CB(scmi_get_cpu_power);
>> bool power_scale_mw;
>> cpumask_var_t scmi_cpus;
>> + cpumask_var_t opp_shared_cpus;
>>
>> if (!zalloc_cpumask_var(&scmi_cpus, GFP_KERNEL))
>> return -ENOMEM;
>> + if (!zalloc_cpumask_var(&opp_shared_cpus, GFP_KERNEL))
>> + return -ENOMEM;
>>
>> cpumask_set_cpu(cpu, scmi_cpus);
>>
>> @@ -240,6 +243,20 @@ static int scmi_init_device(const struct scmi_handle
>> *handle, int cpu)
>> goto free_cpumask;
>> }
>>
>> + /*
>> + * The OPP 'sharing cpus' info may come from dt through an empty opp
>> + * table and opp-shared. If found, it takes precedence over the SCMI
>> + * domain IDs info.
>> + */
>> + ret = dev_pm_opp_of_get_sharing_cpus(cpu_dev, opp_shared_cpus);
>
> If this succeeds, you shouldn't even try to call the other
> get_sharing_cpus variant.
IIUC you mean the above scmi_get_sharing_cpus() ?
It is actually required to do so, cause we need the info of SCMI domains,
regardless of the clock-sharing lines. When we have opp-sharing cpus we still
need to control the SCMI domains as usual.
>
>> + if (ret || !cpumask_weight(opp_shared_cpus)) {
>> + /*
>> + * Either opp-table is not set or no opp-shared was found,
>> + * use the information from SCMI domain IDs.
>> + */
>> + cpumask_copy(opp_shared_cpus, scmi_cpus);
>> + }
>> +
>> /*
>> * 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.
>> @@ -252,7 +269,7 @@ static int scmi_init_device(const struct scmi_handle
>> *handle, int cpu)
>> goto free_cpumask;
>> }
>>
>> - ret = dev_pm_opp_set_sharing_cpus(cpu_dev, scmi_cpus);
>> + 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);
>> @@ -269,7 +286,7 @@ static int scmi_init_device(const struct scmi_handle
>> *handle, int cpu)
>> }
>>
>> power_scale_mw = handle->perf_ops->power_scale_mw_get(handle);
>> - em_dev_register_perf_domain(cpu_dev, nr_opp, &em_cb, scmi_cpus,
>> + em_dev_register_perf_domain(cpu_dev, nr_opp, &em_cb,
>> opp_shared_cpus,
>> power_scale_mw);
>> }
>>
>> @@ -284,6 +301,7 @@ static int scmi_init_device(const struct scmi_handle
>> *handle, int cpu)
>>
>> free_cpumask:
>> free_cpumask_var(scmi_cpus);
>> + free_cpumask_var(opp_shared_cpus);
>> return ret;
>> }
>>
>> --
>> 2.27.0
>
Many thanks,
Nicola
