On Tue, 7 Sept 2021 at 17:34, Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote: > > On Sun, 29 Aug 2021 at 17:54, Dmitry Baryshkov > <dmitry.baryshkov@xxxxxxxxxx> wrote: > > > > On Sun, 29 Aug 2021 at 06:51, Stephen Boyd <sboyd@xxxxxxxxxx> wrote: > > > > > > Quoting Dmitry Baryshkov (2021-08-26 14:56:23) > > > > On 26/08/2021 21:31, Stephen Boyd wrote: > > > > > Quoting Dmitry Baryshkov (2021-07-27 13:19:56) > > > > >> On SM8250 both the display and video clock controllers are powered up by > > > > >> the MMCX power domain. Handle this by linking clock controllers to the > > > > >> proper power domain, and using runtime power management to enable and > > > > >> disable the MMCX power domain. > > > > >> > > > > >> Dependencies: > > > > >> - https://lore.kernel.org/linux-arm-msm/20210703005416.2668319-1-bjorn.andersson@xxxxxxxxxx/ > > > > >> (pending) > > > > > > > > > > Does this patch series need to go through the qcom tree? Presumably the > > > > > dependency is going through qcom -> arm-soc > > > > > > > > It looks like Bjorn did not apply his patches in the for-5.15 series, so > > > > we'd have to wait anyway. Probably I should rebase these patches instead > > > > on Rajendra's required-opps patch (which is going in this window). > > > > > > > > > > Ok. Thanks. I'll drop it from my queue for now. > > > > Just for the reference. I've sent v7 of this patchset. After thinking > > more about power domains relationship, I think we have a hole in the > > abstraction here. Currently subdomains cause power domains to be > > powered up, but do not dictate the performance level the parent domain > > should be working in. > > That's not entirely true. In genpd_add_subdomain() we verify that if > the child is powered on, the parent must already be powered on, > otherwise we treat this a bad setup and return an error code. > > What seems to be missing though, is that if there is a performance > state applied for the child domain, that should be propagated to the > parent domain too. Right? > > > While this does not look like an issue for the > > gdsc (and thus it can be easily solved by the Bjorn's patches, which > > enforce rpmhpd to be powered on to 'at least lowest possible' > > performance state, this might be not the case for the future links. I > > think at some point the pd_add_subdomain() interface should be > > extended with the ability to specify minimum required performance > > state when the link becomes on. > > I guess that minimum performance state could be considered as a > "required-opp" in the DT node for the power-domain provider, no? Yes, up to some point. But this enforces a particular driver code (that I've had to change from v6 to v7). In v6 the gdsc's power_on code would pm_runtime_get() the provider device, power on the domain and the pm_runtime_put() the provider device. Thus the gdsc genpd would be powered on (keeping parent domains in the on state), but the provider device itself would be runtime-suspended (neat idea by Bjorn). However this relied on changes in rpmhpd behaviour (which still did not make it to linux-next). In v7 we have to keep the provider device in resumed state while the gdsc genpd is powered on (to keep the required-opps vote in place). I suppose that 'child requires minimum parent's performance state' might become common property at some point, allowing us to drop this pm_runtime handling. > Another option would simply be to manage this solely in the > platform/soc specific genpd provider. Would that work? Yes, I've had this in the very old iteration of mmcx fixup patchset (even before mmcx-regulator came into play). It ended up with quite an ugly piece of code. > > > Until that time I have changed code to > > enforce having clock controller in pm resume state when gdsc is > > enabled, thus CC itself votes on parent's (rpmhpd) performance state. > > > > > > -- > > With best wishes > > Dmitry > > Kind regards > Uffe -- With best wishes Dmitry
