Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> writes: > Hi Kevin, Arnd, > > I've been giving this some more thoughts... > > On Wed, Nov 26, 2014 at 9:11 PM, Kevin Hilman <khilman@xxxxxxxxxx> wrote: >> Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> writes: >>> On Mon, Nov 24, 2014 at 9:15 PM, Arnd Bergmann <arnd@xxxxxxxx> wrote: >>>> On Monday 24 November 2014 21:10:05 Geert Uytterhoeven wrote: >>>>> As this minimal BSC driver isn't hardware-specific at all, I'm wondering >>>>> if there's a simpler way to do this? >>>>> - Should the driver be renamed to "simple-bus", and match "simple-bus"? >>>>> - Should this be moved to core code, without an explicit driver for >>>>> "simple-bus"? I.e. should the driver core just enable runtime PM for >>>>> all devices not bound to a driver, as they may represent buses with >>>>> child devices that do rely on runtime PM? >>>>> >>>>> Thanks for your comments and suggestions! >>>> >>>> My understanding of simple-bus is that it's something that does >>>> not have any power-management capabilities, and I'd rather not >>>> add clocks or interrupts to it. > > Should I not add the interrupt to the device node, even though I do > know the hardware block has an interrupt? > Of course, to make use of the interrupt, you do need a hardware-specific > driver that binds to the specific compatible name. But for now such a > driver is overkill, as I do not need to use the interrupt. > > Power domains (and clocks used for power management) are different, > as they are platform features: they may appear in any device node, even if > the bindings for the device node don't mention them. > Else I cannot add them to a node that's compatible with e.g. "arm,cortex-a15" > or "arm,pl310-cache", without adding (or completely replacing them with) > compatible names like "renesas,r8a73a4-cortex-a15" resp. > "renesas,sh73a0-pl310-cache"? > Hence I think they should be allowed in "simple-bus" nodes, too. > >>>> What I think makes more sense is to have a bus driver for it >>>> in drivers/bus, remove the "simple-bus" compatibility value >>>> and have the driver take care of registering the power domain >>>> and probing the child devices using of_platform_populate on >>>> itself. >>> >>> Registering power domains is already handled by the core code. >>> >>> So compared to my RFC code, I only have to >>> 1. Drop "simple-bus" from the compatible property in the .dtsi, >>> 2. Call of_platform_populate() from renesas_bsc_probe(), to >>> register the child devices, now the core code no longer does that. >>> >>> I find it a bit strange having to add _more_ code, as the core code handles >>> registering child devices fine. Doing it from my bus driver only protects >>> against people trying to run a kernel without my bus driver included >>> (which currently works fine, as long as no PM domain or clock is involved, >>> e.g. if the clock is forgotten in the SoC's .dtsi :-). >> >> I actually rather like the simple bus driver in it's current form, where >> the device and pm-domain registration is taken care of by the >> core. Since it's really not HW specific at all, maybe just rename it >> simple-pm-bus or something like that? > > That means writing bindings for a new bus type "simple-pm-bus"? Well, I'm OK with adding common properties to simple-bus also, but presuably you'll want to document those as well in a binding doc for simple-bus. Kevin -- 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
