Hi PM posse! On 23/09/16 15:27, Geert Uytterhoeven wrote: > Hi Jon, > > On Fri, Sep 23, 2016 at 2:57 PM, Jon Hunter <jonathanh@xxxxxxxxxx> wrote: >> On 21/09/16 15:57, Geert Uytterhoeven wrote: >>> On Wed, Sep 21, 2016 at 4:37 PM, Jon Hunter <jonathanh@xxxxxxxxxx> wrote: >>>> On 21/09/16 09:53, Geert Uytterhoeven wrote: >>>>> On Tue, Sep 20, 2016 at 12:28 PM, Jon Hunter <jonathanh@xxxxxxxxxx> wrote: >>>>>> Some devices may require more than one PM domain to operate and this is >>>>>> not currently by the PM domain framework. Furthermore, the current Linux >>>>>> 'device' structure only allows devices to be associated with a single PM >>>>>> domain and so cannot easily be associated with more than one. To allow >>>>>> devices to be associated with more than one PM domain, if multiple >>>>>> domains are defined for a given device (eg. via device-tree), then: >>>>>> 1. Create a new PM domain for this device. The name of the new PM domain >>>>>> created matches the device name for which it was created for. >>>>>> 2. Register the new PM domain as a sub-domain for all PM domains >>>>>> required by the device. >>>>>> 3. Attach the device to the new PM domain. >>>>> >>>>> This looks a suboptimal to me: if you have n devices sharing the same PM >>>>> domains, you would add n new subdomains? >>>> >>>> BTW, would this be the case today for some renesas devices or are you >>>> just pointing this out as something that could be optimised/improved? >>> >>> This is the case for all Renesas SoCs that have power areas: devices belong >>> to both the PM domain for the power area, and to the PM domain for the clock >>> domain. >> >> To quantify this a bit, for the Renesas case, how many of these >> duplicated domains would there be if you were to use this approach as-is? > > for i in $(git grep -l renesas, -- "*dts*") ; do echo --- $i ---; git > grep -w power-domains $i | sort | uniq -c | sort -n;done > > tells you how many (supported) devices are (currently) present in each > PM domain. > Most of these (all but devices in CPU/SCU power areas) are also part of a > clock domain. > The synthetic R8A779*_PD_ALWAYS_ON domains could be dropped again, > as we could just refer to the CPG/MSSR node for the clock domain instead. > > For older SH/R-Mobile SoCs with lots of hierarchical domains, that gives us, > after removing the above: > > 1 arch/arm/boot/dts/r8a7740.dtsi: power-domains = <&pd_a4mp>; > 1 arch/arm/boot/dts/r8a7740.dtsi: power-domains = <&pd_d4>; > 2 arch/arm/boot/dts/r8a7740.dtsi: power-domains = <&pd_c5>; > 3 arch/arm/boot/dts/r8a7740.dtsi: power-domains = <&pd_a4r>; > 6 arch/arm/boot/dts/r8a7740.dtsi: power-domains = <&pd_a4s>; > 15 arch/arm/boot/dts/r8a7740.dtsi: power-domains = <&pd_a3sp>; > > R-Car Gen1/Gen2 have all devices in the "always on" PM domain, so they're > not affected. > > R-Car Gen3 again has devices in power areas, mostly for graphics related > purposes: > > 16 arch/arm64/boot/dts/renesas/r8a7795.dtsi: > power-domains = <&sysc R8A7795_PD_A3VP>; Does anyone have any more inputs comments on this? Does it look complete bonkers or should I forge ahead with this? Cheers Jon -- nvpublic
