On Thu, Feb 11, 2021 at 1:14 PM Stephen Boyd <swboyd@xxxxxxxxxxxx> wrote: > > Quoting Matthias Kaehlcke (2021-02-10 14:20:18) > > > > On Wed, Feb 10, 2021 at 10:06:45PM +0100, Krzysztof Kozlowski wrote: > > > > > > This looks hackish... what if later we have something else than hub? > > > Another if()? > > > > > > What if hub could be connected to something else than XHCI controller? > > > > In earlier versions this was standalone driver, which was more flexible and > > didn't require cooperation from the XHCI driver: > > > > https://lore.kernel.org/patchwork/patch/1313001/ > > > > Rob Herring raised objections about the DT bindings, since the USB hub would be > > represented twice in the DT, once in the USB hierachry (with an explicit node or > > implicitly) plus a node for the platform device for the new driver: > > > > https://lore.kernel.org/patchwork/patch/1305395/ > > https://lore.kernel.org/patchwork/patch/1313000/ > > > > Alan Stern suggested to create the platform device in the XHCI platform driver: > > > > https://lore.kernel.org/patchwork/patch/1313000/#1510227 > > > > I wasn't super happy about involving xhci-plat, but at least the code is minimal > > and all the device specific stuff is handled by the onboard_usb_hub driver. > > > > If you have better suggestions that might satisfy all parties please let us > > know :) > > > > Is it possible to use the graph binding to connect the USB controller on > the SoC to the port on the hub? Then the hub would be a standalone node > at the root of DT connected to the USB controller (or phy) and xhci code > could probe the firmware to see if there's a graph connection downstream > that is a powered hub like this. I didn't see this idea mentioned in the > previous discussions, but maybe I missed it. An orphan at the root node is exactly what I don't want to see here. I'm happy with the binding now from a skim of it. The kernel support does seem kind of hacky though. Rob
