On 09/05/17 14:29, Jassi Brar wrote: > On Tue, May 9, 2017 at 6:11 PM, Sudeep Holla <sudeep.ho...@arm.com> wrote: >> On 09/05/17 12:55, Jassi Brar wrote: > >>>>>>> >>>>>>> If it is still not clear, please share your client driver. I >>>>>>> will adapt that to work with existing MHU driver & bindings. >>>>>>> >>>>>> >>>>>> Just take example of SCPI in the mainline. Assume there's another >>>>>> protocol SCMI which uses few more bits in the same channel and the >>>>>> remote firmware implements both but both are totally independent >>>>>> and not related/linked. Also be keep in mind that SCPI is used by >>>>>> other platforms and so will be the new protocol. We simply make >>>>>> SCPI or SCMI bindings aligned to ARM MHU. That's ruled out. >>>>>> >>>>> Not sure what you mean by "that's ruled out". >>>> >>>> 1. The mailbox client bindings should be independent of this ARM MHU >>>> mailbox bindings >>>> 2. All we need in client is a mailbox to point at and not any meta data >>>> That's what I meant by ruled-out as both client and MHU can be used >>>> independent of each other and *should not* be linked. >>>> >>> I am shocked at this coming from you. >>> >>> You design SCMI based upon MHU assumption of single bit "doorbell" and >>> then you say a client should be independent of the underlying >>> controller? Do you intend SCMI to work only over MHU? >>> >> >> No, I never said that. What I said is SCMI protocol will be on doorbell >> based. >> > What if a controller does not support your definition of "doorbell"? > Like PL320 from ARM and many others. >
OK, why are we discussing that here ? >>> What if some controller does not support the simple "doorbell" and >>> expects detailed info? For example, apart from SCMI, the remote also >>> supports platform specific functions like thermal, watchdog, wakeup >>> etc. The SCMI's would just be a subset of the full command set. >>> You/SCMI can not dictate what numerical value the platform assigns to >>> SCMI commands... >> >> What ? That's the whole point of specification. The command set is >> *fixed* and can be implemented on any platform and have generic driver >> for that. >> > The code/value for commands in SHM data packet is SCMI specific. But > what a platform assigns to THIS_IS_SCMI_DOORBELL is going to be > platform specific i.e, not always BIT(x) > Platform which uses this as single bit doorbell has to just choose the tuple(bit and the register set) as shown in the example binding >>>> On digging more about different mailbox controllers, I found >>>> mailbox-sti.c has exactly similar logic as what I have done in this series. >>>> >> >> Did you look at this driver ? >> > Dude, I merged this driver upstream! I don't remember exactly about > STI controller, but it definitely is different from MHU. > Yes I can know and can see you have upstreamed the driver. I have spoken to the ARM MHU hardware IP designers and I know what it's designed for. And that's why I gave you example to look at STI driver to help you understand what I am trying to say faster. >>>> Also don't mix implementation with the binding. I need a simple answer >>>> in this binding. How do I represent specific bits if each bit is >>>> implemented as a doorbell ? That's all. First let's agree on that when >>>> we use this mailbox independently and please *don't mix* with any >>>> client here. It's simple, this controller has 2-3 sets of 32 doorbell >>>> bits. And I am aiming to come up with the binding for that as your >>>> initial bindings didn't consider that. >>>> >>> Please send in whatever changes you plan to do, and I'll modify it so >>> we don't have to bloat the MHU driver and add bindings for a software >>> feature. Until then ... Cheers! >>> >> >> Changes to what ? arm_mhu.c ? This series is complete and implements >> doorbell completely. >> > Send in the user/client driver that you think can not work with > existing driver/bindings. > Again for the 3rd time see arm_scpi.c ARM is now generalizing it with multiple vendors under the new name ARM SCMI. And Juno is implementing using few doorbell bits on the same channel as SCPI. -- Regards, Sudeep
