On 21-03-18, 18:21, Shunyong Yang wrote: > When multiple cpus are related in one cpufreq policy, the first online cpu > will be chosen by default to handle cpufreq operations. In a CPPC case, > let's take two related cpus, cpu0 and cpu1 as an example. > > After system start, cpu0 is the first online cpu. Cpufreq policy will be > allocated and init() in cpufreq_driver will be called to initialize cpu0's > perf capabilities and policy parameters.
Not exactly. The init() is called to initialize stuff for all the CPUs that should be part of policy->related_cpus after init() has returned. So you should initialize perf capabilities for all of them. > When cpu1 is online, current code > will not call init() in cpufreq_driver as policy has been allocated and > activated by cpu0. So, cpu1's perf capabilities are not initialized > (all 0s). > > When cpu0 is offline, policy->cpu will be shifted to cpu1. As cpu1's perf > capabilities are 0s, speed change will not take effect when setting > speed. > > This patch adds calling init() of cpufreq_driver when policy inactive cpu > comes to online. No CPU should be inactive here, its just that you haven't initialized it properly. And we are not going to call init() multiple times for a group of CPUs. That's not what the purpose of init() is. -- viresh
