On Wed, Jun 18, 2014 at 9:44 AM, Kevin Hilman <khilman@xxxxxxxxxx> wrote: [...] > Thinking more about what this RPM driver actually does, and since you > mentioned patterns across SoCs, it seems to me the RPM driver bascially > just doing the IPC. > Yes, technically this is IPC. But it's all exposed in memory as if it was hardware, so there's no messages or packets to be interpreted by the other side. > So, rather than MFD or drivers/soc, it seems to me that it should be > implmented as a controller in the new common mailbox framwork[1] being > worked on by Jassi Brar (added to Cc.) > > IIUC, RPM is actually only doing one-way IPC (it only exposes a write() > interface to clients) so it seems like a rather simple implementation of > a mailbox controller. > What I think you miss here is the detail of that what the regulator writes is not what is passed over the IPC, but rather is just an interface to abstract away how things are spread our in the register space. So the only place where we do have a "mailbox" here is the actual function call between the regulator and the rpm drivers; not between the rpm driver and the rpm. > I believe Bjorn is already on the list of folks Cc'd on the common > mailbox framework, so it would be good to hear from him why RPM wouldn't > fit under that framework. > In a separate group of Qualcomm platforms the communication with the RPM is done by passing messages over a shared memory channel; as this requires a completely different implementation of the rpm driver, I have started to look at Jassi's patch series. Unfortunately at this point it does not look like the proposed mailbox framework would reduce the complexity of the implementation nor provide any additional benefits when it comes to being able to exchange the underlaying communication methods. But I will continue to follow the development of the mailbox framework. Regards, Bjorn -- 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
