Messages in this thread | | | Date | Wed, 9 Aug 2017 15:36:51 +0530 | From | Viresh Kumar <> | Subject | Re: [PATCH v2 17/18] cpufreq: add support for CPU DVFS based on SCMI message protocol |
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On 09-08-17, 10:59, Sudeep Holla wrote: > On 09/08/17 05:18, Viresh Kumar wrote:
> > This stores the same handle pointer which is stored in the global variable > > below. Right? Why keep a local variable here at all ? > > Yes, you are right. Initially, started with just private pointers and > then added global. I was thinking of calling devm_scmi_handle_get per > policy to reflect the refcount correctly and drop global variable. Let > me know what you think.
A refcount of 1 should be fine as well, i.e. For the cpufreq driver. Why would SCMI care if we manage multiple policies here ? Unless it makes something within SCMI core better.
> > This is something special which is used only when we are returning indexes and > > I am not sure if this will have benefit here. I will rather return 0 here. > > That's what other drivers are doing. > > Indeed had 0 initially but changed as per Juri's suggestion.
Maybe he suggested doing that in the fast switch routine ? As that's the normal protocol there. Though I have sent a patch today to propose using 0 there as well (you cc'd).
> But is 0 > treated as failure and still running at current OPP ?
You have used that in the ->get() routine. So the OPP isn't changing, but we are just trying to fetch it. cpufreq core doesn't do a lot with the value returned from here, but at one place we break early if 0 is returned. And so all drivers are returning that.
> and not 0KHz I assume.
Yeah, 0 KHz is dead CPU really :)
> > I suppose any CPU can change the frequency of any other CPU here, right? You > > must set policy->dvfs_possible_from_any_cpu = true, from ->init() then. > > > > OK, I missed to see something like that exists, will do.
Fairly recent stuff, present in pm/linux-next only.
> >> + /* > >> + * But we need OPP table to function so if it is not there let's > >> + * give platform code chance to provide it for us. > >> + */ > > > > How are we getting the OPPs? DT or non DT ? > > > > Non DT :), from the firmware.
I would improve the above comment in that case to clearly say that OPPs are added by the platform, lets wait for it.
-- viresh
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