On 03/02/2014 09:54 PM, Mark Brown wrote: > On Mon, Feb 24, 2014 at 08:38:07AM -0600, Nishanth Menon wrote: > >> Intent here is to allow drivers such as cpufreq-cpu0 to be reused on >> platforms such as TI's OMAP derivatives, and other SoCs which differ >> only by the sequence involved in voltage scale operations. So, this >> patch provides a framework for registering the underlying >> implementation of the SoC specific voltage change methodology. > > That bit is clear, what's very opaque from the code is how this is going > to be accomplished. The SoC specific voltage domain drivers register with devm_voltdm_register. the fops provide the abstraction needed for the SoC (example in patch #5 - which introduces OMAP specific voltage domain which handles ABB and VDD regulators). What would you suggest that we do to clarify the usage here? >> Overall the sequence takes place after this patch is as follows: >> a) voltage domain drivers such as those of TI or others register with >> voltage domain with devm_voltdm_register. >> b) cpufreq-cpu0/devfreq drivers: >> of_pm_voltdm_notifier_register(introduced as part of patch #1) to >> register notifiers around clk of interest. This request is linked to >> the specific voltage domain using phandle in device tree. >> c) when cpufreq-cpu0/devfreq does a clk_set_rate, the common clock >> framework triggers notifiers in voltage domain core which in turn, >> invokes the corresponding handlers for the voltage domain driver >> ensuring the right dvfs sequence specific to the SoC is triggered. > > So the first question I have here is what happens if multiple clocks > need to be updated in lock step - if we're only triggering off clock > notifiers that seems tricky. The other thing here is that the fact that Yes, that is true, however, there are ways to implement them, for example: We could implement an higher level clock that takes care of the multiple clock node control to handle this kind of scenario. I can elaborate that in the commit message, if that is desirable. > your API is "of_" suggests that it is in fact linked very srongly to DT > - it'd be good to split out the layers to make sure things make sense > standalone, the DT helpers are obviously good but the API should be able > to stand separately. You are correct, I had intended the RFC as purely "OF only". I will make it independent of of in the next revision. -- Regards, Nishanth Menon -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
