On Thu, Jan 18, 2024 at 12:15:27PM +0100, Greg Kroah-Hartman wrote: > On Thu, Jan 18, 2024 at 11:58:50AM +0100, Bartosz Golaszewski wrote: > > On Wed, Jan 17, 2024 at 5:45 PM Greg Kroah-Hartman > > <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > > > > > > On Wed, Jan 17, 2024 at 05:07:43PM +0100, Bartosz Golaszewski wrote: > > > > From: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx> > > > > > > > > In order to introduce PCI power-sequencing, we need to create platform > > > > devices for child nodes of the port node. > > > > > > Ick, why a platform device? What is the parent of this device, a PCI > > > device? If so, then this can't be a platform device, as that's not what > > > it is, it's something else so make it a device of that type,. > > > > > > > Greg, > > > > This is literally what we agreed on at LPC. In fact: during one of the > > hall track discussions I said that you typically NAK any attempts at > > using the platform bus for "fake" devices but you responded that this > > is what the USB on-board HUB does and while it's not pretty, this is > > what we need to do. > > Ah, you need to remind me of these things, this changelog was pretty > sparse :) > I believe I missed this part of the discussion, why does this need to be a platform_device? What does the platform_bus bring that can't be provided by some other bus? (I'm not questioning the need for having a bus, creating devices, and matching/binding them to a set of drivers) Regards, Bjorn > > Now as for the implementation, the way I see it we have two solutions: > > either we introduce a fake, top-level PCI slot platform device device > > that will reference the PCI host controller by phandle or we will live > > with a secondary, "virtual" platform device for power sequencing that > > is tied to the actual PCI device. The former requires us to add DT > > bindings, add a totally fake DT node representing the "slot" which > > doesn't really exist (and Krzysztof already expressed his negative > > opinion of that) and then have code that will be more complex than it > > needs to be. The latter allows us to not change DT at all (other than > > adding regulators, clocks and GPIOs to already existing WLAN nodes), > > reuse the existing parent-child relationship between the port node and > > the instantiated platform device as well as result in simpler code. > > > > Given that DT needs to be stable while the underlying C code can > > freely change if we find a better solution, I think that the second > > option is a no-brainer here. > > Ok, I remove my objections, sorry about that, my confusion. > > greg k-h
