Re: [RFT PATCH 1/3] usb: misc: usb3503: Fix HUB mode after bootloader initialization

From: Rob Herring
Date: Tue May 03 2016 - 14:00:36 EST

On Mon, May 02, 2016 at 11:55:01AM +0100, Mark Brown wrote:
> On Mon, May 02, 2016 at 11:49:12AM +0200, Krzysztof Kozlowski wrote:
> > This VDD regulator supply actually is not a usb3503 USB HUB regulator
> > supply... but a supply to the LAN attached to this HUB. Regulator off/on
> > is needed for LAN to show up. The hub will show up with typical reset
> > (which is also missing before my patchset btw).
> > The LAN, as a USB device, is auto-probed so it cannot take the regulator
> > and play with it. The simplest idea I have is to add it as "external
> > supply" to the parent: usb3503.
> This is common enough that that just isn't going to scale well I fear
> without some generic handling, either walking child devices at the bus
> level or at the device level with a pre-probe() callback to get the
> device to power on. The latter is more appropriate to things like
> Slimbus where the device is more likely to do active management at
> runtime, it's not clear people are building USB devices like that.

There's a new binding and support in -next (.../usb/usb-device.txt) for
USB devices that should help here. Though, how to handle a hub on USB
and I2C buses would need to be worked out.