On Fri, 18 Dec 2020, Mark Brown wrote: > On Fri, Dec 18, 2020 at 08:10:51AM +0100, Greg KH wrote: > > On Thu, Dec 17, 2020 at 10:19:37PM +0100, Alexandre Belloni wrote: > > > > There is something I don't get from the documentation and it is what is > > > this introducing that couldn't already be done using platform drivers > > > and platform devices? > > > Because platform drivers and devices should ONLY be for actual platform > > devices. Do NOT use that interface to fake up a non-platform device > > (i.e. something that is NOT connected to a cpu through a memory-mapped > > or direct-firmware interface). > > > Do not abuse the platform code anymore than it currently is, it's bad > > enough what has been done to it over time, let's not make it any worse. > > I am not clear on why you're giving direct-firmware devices (which I > assume means things like ARM SCMI where we're talking directly to some > firmware?) a pass here but not for example a GPIO controlled devices. > If this is mainly about improving abstractions it seems like the > boundary here isn't great. Or perhaps I'm just missing what > direct-firmware is supposed to mean? > > In any case, to be clear part of what you're saying here is that all > I2C and SPI MFDs should be rewritten to use this new bus - I've just > copied Lee in again since he keeps getting missed from these threads. > As previously discussed this will need the auxilliary bus extending to > support at least interrupts and possibly also general resources. Thanks Mark. Not entirely sure why this needed an entirely new subsystem to handle non-MMIO Multi-Functional Devices (MFD). Or why I was not approached by any of the developers during the process. Having 2 entirely separate subsystems where MFDs can now be registered sounds confusing and convoluted at best. Why not simply extend actual MFD to be capable of registering non-pure platform devices via other means? By doing so you keep things bound to a central location resulting in less chance of misuse. I turn away MFD implementation abuses all the time. Seeing as the 2 subsystems are totally disjoint, this just unwittingly opened up another back-channel opportunity for those abuses to make it into the mainline kernel. -- Lee Jones [李琼斯] Senior Technical Lead - Developer Services Linaro.org │ Open source software for Arm SoCs Follow Linaro: Facebook | Twitter | Blog
