On Fri, Dec 20, 2019 at 12:27:39PM +0100, Ulf Hansson wrote: > On Fri, 20 Dec 2019 at 11:07, Sudeep Holla <sudeep.holla@xxxxxxx> wrote: [...] > > > > Even if you don't create all these genpd domains, it is still degraded > > mode and we are anyway not changing that. Let me know if my understanding > > is wrong here. > > Your understanding is wrong. > > If I remove the genpds because psci_set_osi_mode() fails, then in the > current suggested initialization path, that will lead to that the > entire cpuidle-psci driver will fail to initiate (which is because > psci_dt_attach_cpu() returns an error). In other words, only WFI state > will be used by cpuidle as there will be no cpuidle driver registered > at all. > > That would not be an acceptable behaviour, as it would make the > situation worse than today. > > What we want in this scenario is to keep using all the idle states for > the CPUs, but ignores those for the cluster. That we both agree on, > right? > Yes, I agree and understand that. I was assuming as part of this change you will fixup psci_dt_cpu_init_idle not to return error but just allow CPU level idle. Sorry if that was not clear, I was always assuming that. > > > > I am sure, DTB may get copied to different platform and the firmware may > > not support OSI. I know we have logs, but creating and leaving those > > genpd domains unused will be just confusing. Please change that. > > We are not creating any genpds unless OSI mode is supported. We do not > even try to attach CPUs to the PM domains, unless OSI mode is > supported. So this should already work according to your expectations > and previous requests. > Yes I understand, but checking if "OSI mode is supported" is not same as "setting OSI mode". Until OSI mode is set, it is default/PC mode, so we need to work based on that assumption. > To address your concern about removing genpds when psci_set_osi_mode() > fails, we also need to address the problems we get when calling > psci_dt_attach_cpu(). There are two viable options as I see it. > Shouldn't that fail ? Sorry, I might be missing something. > 1. Prevent calling psci_dt_attach_cpu() altogether when > psci_set_osi_mode() failed. This means another function needs to be > shared from cpuidle-psci-domain.c to let cpuidle-psci.c know about it. > If we don't create any genpd, will psci_dt_attach_cpu fail ? > 2. We can let psci_dt_attach_cpu() return NULL, when > psci_set_osi_mode() failed - as this information is already known by > cpuidle-psci-domain.c. > Yes I was making all the arguments/discussion based on that. Do you see any issues with that ? Any races possible ? > I vote for option 2, but what do you think? > Me too from the time I started the discussion, I assume a lot and don't put this into words in the email. -- Regards, Sudeep
