On 20/01/2020 19:38, Lukasz Luba wrote:
On 1/20/20 6:27 PM, Dietmar Eggemann wrote:
On 20/01/2020 16:09, Quentin Perret wrote:
Hey Lukasz,
On Monday 20 Jan 2020 at 14:52:07 (+0000), Lukasz Luba wrote:
On 1/17/20 10:54 AM, Quentin Perret wrote:
[...]
It's true that we need the policy->cpus cpumask only for cpu devices and we have it available when we call em_register_perf_domain() [scmi-cpufreq.c driver] or the OPP wrapper dev_pm_opp_of_register_em() [e.g. cpufreq-dt.c driver].
And we shouldn't make EM code dependent on OPP.
But can't we add 'struct cpumask *mask' as an additional argument to both which can be set to NULL for (devfreq) devices?
We can check in em_register_perf_domain() that we got a valid cpumask for a cpu device and ignore it for (devfreq) devices.
I think we could avoid this additional argument 'cpumask'. I have checked the cpufreq_cpu_get function, which should do be good for this:
---------->8------------------------- static int _get_sharing_cpus(struct device *cpu_dev, struct cpumask *span) { struct cpufreq_policy *policy;
policy = cpufreq_cpu_get(cpu_dev->id); if (policy) { cpumask_copy(span, policy->cpus); cpufreq_cpu_put(policy); return 0; } else { return -EINVAL; } } --------------------------8<-------------------------------
It would be a replacement for: ret = dev_pm_opp_get_sharing_cpus(dev, span);
True. But then we hard-code that a CPU device performance domain can only be a frequency domain (which is true today).
The task scheduler (build_perf_domains()) and thermal are already using cpufreq_cpu_get() to access the cpufreq policy. Now the EM framework would too for CPU devices. I assume that could work with a couple of adaptations in Documentation/power/energy-model.rst.
BTW, there is a similar interface cpufreq_get_policy() in cpufreq.c which is used less often?