On 23 January 2017 at 21:11, Dave Gerlach <d-gerlach@xxxxxx> wrote: > On 01/20/2017 10:52 AM, Ulf Hansson wrote: >> >> [...] >> >>>>> Another option is create something new either common or TI SCI >>>>> specific. It could be just a table of ids and phandles in the SCI >>>>> node. I'm much more comfortable with an isolated property in one node >>>>> than something scattered throughout the DT. >>>> >>>> >>>> To me, this seems like the best possible solution. >>>> >>>> However, perhaps we should also consider the SCPI Generic power domain >>>> (drivers/firmware/scpi_pm_domain.c), because I believe it's closely >>>> related. >>>> To change the power state of a device, this PM domain calls >>>> scpi_device_set|get_power_state() (drivers/firmware/arm_scpi.c), which >>>> also needs a device id as a parameter. Very similar to our case with >>>> the TI SCI domain. >>>> >>>> Currently these SCPI device ids lacks corresponding DT bindings, so >>>> the scpi_pm_domain tries to work around it by assigning ids >>>> dynamically at genpd creation time. >>>> >>>> That makes me wonder, whether we should think of something >>>> common/generic? >>> >>> >>> When you say something common/generic, do you mean a better binding for >>> genpd, >>> or something bigger than that like a new driver? Because I do think a >>> phandle >>> cell left open for the genpd provider to interpret solves both the scpi >>> and >>> ti-sci problem we are facing here in the best way. Using generic PM >>> domains lets >>> us do exactly what we want apart from interpreting the phandle cell with >>> our >>> driver, and I feel like anything else we try at this point is just going >>> to be >>> to work around that. Is bringing back genpd xlate something we can >>> discuss? >> >> >> Bringing back xlate, how would that help? Wouldn't that just mean that >> you will get one genpd per device? That's not an option, I think we >> are all in agreement to that. > > > Sure, perhaps the custom xlate wouldn't be the right way to do it, as we > wouldn't be able to associate a device directly to a phandle, at least with > how it was implemented before, but I think we can skip that entirely. Does > opening up the interpretation of the cells of the 'power-domains' phandle > not solve all of these issues? Is that out of the question? > > genpd_xlate_simple currently just makes sure the args_count of the > 'power-domains' phandle was zero and bails if it was not. Why couldn't we > remove this check and let the driver interpret it while still using > of_genpd_add_provider_simple to register the provider? It's still a 'simple' > provider from the perspective of the genpd framework and the actual pm > domain mapping will not change, but now the driver can parse the cells and > do whatever it needs to, such as reading a device id. > > I think that's a bit more flexible and will avoid breaking anything that is > there today. Would you mind providing an example? Perhaps also some code snippets dealing with the parsing? Kind regards Uffe -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
