Hi Geert, On 21/09/16 15:57, Geert Uytterhoeven wrote: > Hi Jon, > > 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? I would like to see some agreement about whether we would allow the 'power-domains' property to have more than one power-domain. We could always improve the implementation in the future. I am quite happy to re-work this RFC to avoid duplicated domains for devices like Renesas if people are on board with the overall proposal. Cheers Jon -- nvpublic
