Re: [PATCH v16 6/7] usb: host: xhci-plat: Create platform device for onboard hubs in probe()

On Wed, Oct 20, 2021 at 02:01:21PM -0700, Matthias Kaehlcke wrote:

On Wed, Oct 20, 2021 at 04:37:20PM -0400, Alan Stern wrote:

quoted

On Wed, Oct 20, 2021 at 01:27:40PM -0700, Matthias Kaehlcke wrote:

quoted

Hi Mathias,

On Wed, Oct 20, 2021 at 04:05:37PM +0300, Mathias Nyman wrote:

quoted

If separate devices for controlling onboard hub power is the right solution then
how about creating the onboard hub device in usb_add_hcd() (hcd.c), and
store it in struct usb_hcd.

A bit like how the roothub device is created, or PHYs are tuned.

Sure, that sounds feasible, even better if it's handled in a single place
and different types of controllers don't have to add support separately.

Bear in mind that this would prevent you from working with onboard
non-root hubs.

My goal is to (architecturally) support nested hubs, but TBH I haven't
looked much into such a configuration since I don't have hardware for
testing. My assumption was that support for onboard hubs connected to
non-root hubs whould have to be added to the generic hub driver.

Could you elaborate in how far you think it would be different for
xhci_plat vs generic hcd?

A lot of this material has slipped from my mind.  However, I don't see 
much difference between those two approaches.

Alan Stern