On Tue, Sep 29, 2020 at 03:09:12PM -0700, Matthias Kaehlcke wrote: > Hi Rob, > > On Tue, Sep 29, 2020 at 03:17:01PM -0500, Rob Herring wrote: > > As I said in prior version, this separate node and 'hub' phandle is not > > going to work. You are doing this because you want a platform driver for > > "realtek,rts5411". That may be convenient for Linux, but doesn't reflect > > the h/w. > > I agree that the hardware representation isn't totally straightforward, however > the description isn't limited to Linux: > > - there is a single IC (like the Realtek RTS5411) > - the IC may require several resources to be initialized in a certain way > - this may require executing hardware specific code by some driver, which > isn't a USB device driver > - the IC can 'contain' multiple USB hub devices, which can be connected to > separate USB busses > - the IC doesn't have a control bus, which somewhat resembles the > 'simple-audio-amplifier' driver, which also registers a platform device > to initialize its resources > > - to provide the functionality of powering down the hub conditionally during > system suspend the driver (whether it's a platform driver or something else) > needs know which USB (hub) devices correspond to it. This is a real world > problem, on hardware that might see wide distribution. > > There were several attempts to solve this problem in the past, but none of them > was accepted. So far Alan Stern seems to think the driver (not necessarily the > binding as is) is a suitable solution, Greg KH also spent time reviewing it, > without raising conceptual concerns. So it seems we have solution that would > be generally landable from the USB side. > > I understand that your goal is to keep the device tree sane, which I'm sure > can be challenging. If you really can't be convinced that the binding might > be acceptable in its current or similiar form then please offer guidance > on possible alternatives which allow to achieve the same functionality. You're really trying to represent this special IC in DT, right? Maybe if you don't call it a "hub" but instead something that better reflects what it actually is and does, the description will be more palatable. Alan Stern
