On 05-11-20, 11:56, Ulf Hansson wrote: > On Thu, 5 Nov 2020 at 11:40, Viresh Kumar <viresh.kumar@xxxxxxxxxx> wrote: > > Btw, how do we identify if it is a power domain or a regulator ? To be honest, I was a bit afraid and embarrassed to ask this question, and was hoping people to make fun of me in return :) > Good question. It's not a crystal clear line in between them, I think. And I was relieved after reading this :) > A power domain to me, means that some part of a silicon (a group of > controllers or just a single piece, for example) needs some kind of > resource (typically a power rail) to be enabled to be functional, to > start with. Isn't this what a part of regulator does as well ? i.e. enabling/disabling of the regulator or power to a group of controllers. Over that the regulator does voltage/current scaling as well, which normally the power domains don't do (though we did that in performance-state case). > If there are operating points involved, that's also a > clear indication to me, that it's not a regular regulator. Is there any example of that? I hope by OPP you meant both freq and voltage here. I am not sure if I know of a case where a power domain handles both of them. > Maybe we should try to specify this more exactly in some > documentation, somewhere. I think yes, it is very much required. And in absence of that I think, many (or most) of the platforms that also need to scale the voltage would have modeled their hardware as a regulator and not a PM domain. What I always thought was: - Module that can just enable/disable power to a block of SoC is a power domain. - Module that can enable/disable as well as scale voltage is a regulator. And so I thought that this patchset has done the right thing. This changed a bit with the qcom stuff where the IP to be configured was in control of RPM and not Linux and so we couldn't add it as a regulator. If it was controlled by Linux, it would have been a regulator in kernel for sure :) -- viresh
