On Tue, Oct 10, 2017 at 4:27 AM, Rob Herring <robh@xxxxxxxxxx> wrote: > 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? > Most (except SCMI) protocols are proprietary and can not be used generically, so the command codes get hardcoded in the client driver. SCMI+MHU is going to be rare case when we have a chance to get the code via DT. >>>>> 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. > Yes. It is only for SCMI protocol running over the variations of MHU controller. Cheers -- 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
