On Mon, Oct 9, 2017 at 9:46 AM, Jassi Brar <jassisinghbrar@xxxxxxxxx> wrote: > On Mon, Oct 9, 2017 at 7:22 PM, Rob Herring <robh@xxxxxxxxxx> wrote: >> On Fri, Oct 6, 2017 at 9:26 PM, Jassi Brar <jassisinghbrar@xxxxxxxxx> wrote: >>> On Fri, Oct 6, 2017 at 9:24 PM, Rob Herring <robh@xxxxxxxxxx> wrote: >>>> On Fri, Oct 6, 2017 at 6:01 AM, Jassi Brar <jassisinghbrar@xxxxxxxxx> wrote: >>>>> On Fri, Oct 6, 2017 at 4:50 AM, Rob Herring <robh@xxxxxxxxxx> wrote: >>>>>> On Thu, Sep 28, 2017 at 02:11:27PM +0100, Sudeep Holla wrote: >>> >>>>>> >>>>>>> +- mbox-data : For each phandle listed in mboxes property, an unsigned 32-bit >>>>>>> + data as expected by the mailbox controller >>>>>> >>>>>> Shouldn't that be cells as part of mboxes property? >>>>>> >>>>> A MHU client can send any number of commands (such u32 values) over a channel. >>>>> This client (SCMI) sends just one command over a channel, but other >>>>> clients may/do send two or more. >> >> The above definition doesn't support 2 or more as it is 1-1 with channels. >> > I thought you suggested to make controller driver accept the command > as another cell in client's mboxes property. > Which we can't do. Yes, agreed. But I'm wondering since a client may need more than one, how would that be expressed? >>>> Okay, then I guess I don't understand why this is in DT. >>>> >>> Yeah the client has to provide code (u32 value) for the commands it >>> sends, and that value is going to be platform specific. For example, >>> on Juno the ITS_AN_SCMI_COMMAND may be defined as BIT(7) while on my >>> platform it may be 0x4567 >>> >>> For MHU based platforms, it becomes easy if the u32 is passed from DT. >>> And that should be ok since that is like a h/w parameter - a value >>> chosen/expected by the remote firmware. >> >> Could it ever be more than 1 cell? >> > SCMI sends sub-commands via SHMEM, so it is always going to be 1cell for _scmi_. > However many firmwares are unlikely to use just one command over a > channel - say, the protocol is trivial or the linux and remote have no > SHMEM. I'd hope the normal case is not enumerating commands and sub-commands in DT and this is special case of a "generic" protocol with platform specific aspects. It could be solved with a specific compatible for each platform/implementation. We'll probably regret not doing that, but I'm going to pretend that this time SoC vendors won't mess it up. >> I guess being in DT is fine, but I'm still not sure about the naming. >> The current name suggests it is part of the mbox binding. Do we want >> that or should it be SCMI specific? Then "data" is vague. Perhaps >> "scmi-commands"? >> > Sure. I have no problem with whatever we wanna call it. Okay. That should have an "arm" prefix too BTW. Rob -- 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
