On Wed, May 19, 2021 at 10:43:56AM -0400, Alan Stern wrote: > On Tue, May 18, 2021 at 02:40:47PM -0700, Matthias Kaehlcke wrote: > > > > Could you also have a look at "[4/5] usb: host: xhci-plat: > > Create platform device for onboard hubs in probe()" > > (https://lore.kernel.org/patchwork/patch/1425453/)? It's a > > relatively short patch that creates the platform device for > > the driver from xhci-plat as you suggested in the v4 > > discussion. > > I'm not the maintainer for xhci-related drivers. > > However, there is at least one thing about this patch which looks > suspicious: Adding the onboard_hub_dev pointer to struct usb_hcd instead > of to struct xhci_plat_priv, where it would make a lot more sense. I can move it to struct usb_hcd if that's preferred > It's also worth mentioning that this approach won't work at all when the > onboard hub is not at the top level (its parent isn't the root hub), Yes, this limitation is mentioned in the commit message of '[2/5] USB: misc: Add onboard_usb_hub driver'. It shouldn't be hard to add support for nested hubs, however I currently have no such configuration for testing, so I prefer to defer it until the need actually arises and it can be tested. > or when more than one onboard hubs are connected to the same root hub. Right, currently that isn't supported. xhci-plat could iterate over the ports and have a list of the platform devices it owns. It would also require some logic to make sure only one platform device is created per hub. Much of this code could probably live in the onboard_hub driver and would also be used if support for non-root hubs is added.
