Messages in this thread | | | From | Ulf Hansson <> | Date | Fri, 9 Jul 2021 16:02:55 +0200 | Subject | Re: [PATCH] PM: domains: Don't attach a device to genpd that corresponds to a provider |
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On Fri, 9 Jul 2021 at 15:58, Geert Uytterhoeven <geert@linux-m68k.org> wrote: > > Hi Ulf, > > On Fri, Jul 9, 2021 at 3:48 PM Ulf Hansson <ulf.hansson@linaro.org> wrote: > > On Fri, 9 Jul 2021 at 15:35, Geert Uytterhoeven <geert@linux-m68k.org> wrote: > > > On Fri, Jul 9, 2021 at 3:23 PM Ulf Hansson <ulf.hansson@linaro.org> wrote: > > > > On Fri, 9 Jul 2021 at 15:07, Geert Uytterhoeven <geert@linux-m68k.org> wrote: > > > > > On Fri, Jul 9, 2021 at 2:56 PM Ulf Hansson <ulf.hansson@linaro.org> wrote: > > > > > > According to the common power domain DT bindings, a power domain provider > > > > > > must have a "#power-domain-cells" property in its OF node. Additionally, if > > > > > > a provider has a "power-domains" property, it means that it has a parent > > > > > > domain. > > > > > > > > > > OK. > > > > > > > > > > > It has turned out that some OF nodes that represents a genpd provider may > > > > > > also be compatible with a regular platform device. This leads to, during > > > > > > probe, genpd_dev_pm_attach(), genpd_dev_pm_attach_by_name() and > > > > > > genpd_dev_pm_attach_by_id() tries to attach the corresponding struct device > > > > > > to the genpd provider's parent domain, which is wrong. Instead the genpd > > > > > > > > > > Why is that wrong? > > > > > > > > It may lead to that the struct device that corresponds to a genpd > > > > provider may be attached to the parent domain. In other words, the > > > > parent domain will not only be controlled by a child domain > > > > (corresponding to the provider), but also through the provider's > > > > struct device. As far as I can tell, this has never been the intent > > > > for how things should work in genpd. > > > > > > Ah, you're worried about the case where the subdomain is a child of > > > the parent domain, but the actual subdomain controller (represented > > > by the platform device) isn't? > > > > Well, even if the platform device represents a subdomain controller, > > should it really be attached to the parent domain? > > That's what the presence of the "power-domains" property means, > isn't it? > If the subdomain controller itself is not part of the parent power > domain, there should not be a "power-domains" property. So perhaps > we need a new property ("power-domain-parent"?) to indicate what is > the parent domain for the subdomains in this case?
Hmm, but perhaps it's just a matter of expectations of what will happen during attach.
On the other hand a new binding for the parent would make it more clear. I wouldn't mind.
> > > In any case, it means that the provider needs to manage runtime PM, > > etc for its struct device to not prevent the parent domain from being > > powered off. > > Shouldn't all drivers for devices that can be somewhere in a PM Domain > hierarchy do that anyway? :-) See e.g. commit 3a611e26e958b037 > ("net/smsc911x: Add minimal runtime PM support"). > > If "simple-bus" would do that, we could get rid of "simple-pm-bus"...
Right, I totally forgot about that. Thanks for reminding me.
As I said in the other thread, let's drop this patch for now.
Kind regards Uffe
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