On Friday 23 January 2015 09:56:51 Geert Uytterhoeven wrote: > >> diff --git a/Documentation/devicetree/bindings/bus/simple-pm-bus.txt b/Documentation/devicetree/bindings/bus/simple-pm-bus.txt > >> new file mode 100644 > >> index 0000000000000000..d03abf7fd8e3997a > >> --- /dev/null > >> +++ b/Documentation/devicetree/bindings/bus/simple-pm-bus.txt > >> @@ -0,0 +1,52 @@ > >> +Simple Power-Managed Bus > >> +======================== > >> + > >> +A Simple Power-Managed Bus is a transparent bus that doesn't need a real > >> +driver, as it's typically initialized by the boot loader. > >> + > >> +However, its bus controller is part of a PM domain, or under the control of a > >> +functional clock. Hence, the bus controller's PM domain and/or clock must be > >> +enabled for child devices connected to the bus (either on-SoC or externally) > >> +to function. > >> + > >> + > >> +Generic compatible values and properties > >> +---------------------------------------- > >> + > >> +Required properties: > >> + - compatible: Must be at least one of the vendor-specific compatible values > >> + from a vendor-specific section below, and "simple-bus" as a > >> + fallback. > > > > What happened to the idea of using something like "simple-pm-bus"? > > I think that's a decision to make by the (successor of the) ePAPR committee. > At least it would be nice to get some feedback from the DT review team > about this. > > If we go that road, the vendor-specific compatible value should still be > documented, else checkpatch will complain when encountering it in a DTS. > Then, should it become > > compatible = "renesas,bsc-sh73a0", "renesas,bsc", "simple-pm-bus", > "simple-bus"; > > or should "simple-bus" just be added to of_default_bus_match_table[], so we > can drop "simple-bus" from the list in the DTS: > > compatible = "renesas,bsc-sh73a0", "renesas,bsc", "simple-pm-bus"; I was thinking of the reverse: drop "simple-bus" bus from the list here, but not add "simple-pm-bus" to of_default_bus_match_table. This will cause child devices to no longer be probed automatically, and you will have to call of_platform_populate() from simple_pm_bus_probe(), after pm_runtime_enable(). This seems like a cleaner model to me, for two reasons: - In the binding, claiming compatibility with "simple-bus" feels wrong to me, because you have a bus that is not as simple as others - The ordering between pm_runtime_enable() and the probing of the child devices is guaranteed, which I think it is not with your current code. Does this make sense, or am I missing an important reason why there has to be a "simple-bus" compatible string here? Arnd -- 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
