On Wed, 26 Jul 2023 at 13:12, Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote: > > On Fri, 21 Jul 2023 at 20:38, Sudeep Holla <sudeep.holla@xxxxxxx> wrote: > > > > On Fri, Jul 21, 2023 at 08:33:04AM -0600, Rob Herring wrote: > > > On Fri, Jul 21, 2023 at 12:55:35PM +0100, Sudeep Holla wrote: > > > > On Fri, Jul 21, 2023 at 01:42:43PM +0200, Ulf Hansson wrote: > > > > > On Wed, 19 Jul 2023 at 17:17, Sudeep Holla <sudeep.holla@xxxxxxx> wrote: > > > > > > > > > > > > On Thu, Jul 13, 2023 at 04:17:35PM +0200, Ulf Hansson wrote: > > > > > > > The protocol@13 node is describing the performance scaling option for the > > > > > > > ARM SCMI interface, as a clock provider. This is unnecessary limiting, as > > > > > > > performance scaling is in many cases not limited to switching a clock's > > > > > > > frequency. > > > > > > > > > > > > > > Therefore, let's extend the binding so the interface can be modelled as a > > > > > > > generic performance domaintoo. The common way to describe this, is to use > > > > > > > the "power-domain" DT bindings, so let's use that. > > > > > > > > > > > > > > > > > > > One thing I forgot to ask earlier is how we can manage different domain IDs > > > > > > for perf and power domains which is the case with current SCMI platforms as > > > > > > the spec never mandated or can ever mandate the perf and power domains IDs > > > > > > to match. They need not be same anyways. > > > > > > > > > > Based upon what you describe above, I have modelled the perf-domain > > > > > and the power-domain as two separate power-domain providers. > > > > > > > > > > A consumer device being hooked up to both domains, would specify the > > > > > domain IDs in the second power-domain-cell, along the lines of the > > > > > below. Then we would use power-domain-names to specify what each > > > > > power-domain represents. > > > > > > > > > > power-domains = <&scmi_pd 2>, <&scmi_dvfs 4>; > > > > > power-domain-names = "power", "perf"; > > > > > > > > > > I hope this makes it clearer!? > > > > > > > > Yes it make is clear definitely, but it does change the definition of the > > > > generic binding of the "power-domains" property now. I am interesting in > > > > the feedback from the binding maintainers with respect to that. Or is it > > > > already present ? IIUC, the ones supported already are generally both > > > > power and performance providers. May be it doesn't matter much, just > > > > wanted to explicit ask and confirm those details. > > > > > > I commented on v1. > > > > > > Looks like abuse of "power-domains" to me, but nothing new really. > > > Please define when to use a power domain vs. a perf domain and don't > > > leave it up to the whims of the platform. Maybe perf domains was a > > > mistake and they should be deprecated? > > > > > > > Just a thought here, instead of deprecating it I was thinking if possible > > to keep the power-domains and performance-domains separate and just extend > > the genpd to handle the latter. There by we are not mixing up and creating > > confusions that need more specific definitions in the binding(which is not > > a big deal) but platforms getting it wrong inspite of that is a big problem. > > Keep it separate makes it more aligned to the hardware and doesn't dilute > > the definitions and probably avoids any possible mistakes due to that. > > > > Sorry Ulf I am just not yet convinced to mix them up yet 😉 and wish you > > don't convince me to. Let me know why the above suggestion won't work. > > The main point I think we need to consider too, is that on some > platforms, the power-domain and the performance-domain are managed > together by the FW. It is not really two separate things and hence it > would not quite be correct to describe it as two different types of > providers in DT. > > If we should follow your suggestion above, to use the > performance-domain bindings, then I think we need an additional new > binding to cover the above mentioned case too. This would lead us into > having one binding for the power-domain, another for the > performance-domain and a third for the power+performance-domain. > > In my opinion this sounds quite like a mess. I would rather keep using > the power-domain bindings for all these cases. Of course, it's a bit > of a stretch too, but I think it should be less confusing in the end, > assuming we extend/clarify the description of the power-domain > bindings, of course. > > Did that convince you? :-) Sudeep, Rob, Can we try to conclude on the way forward? Is it acceptable to keep using the power-domain bindings (with some clarifications) for performance domains or should we start moving to the performance-domain bindings? If moving to the performance-domain binding, should we start migrating existing users of the power-domain binding too - or what is your take on this? Kind regards Uffe
