[REPOST PATCH 3/3] USB: dwc2: Don't turn off the usbphy in suspend if wakeup is enabled

Alan Stern stern at rowland.harvard.edu
Wed Jul 8 12:58:14 PDT 2015

On Wed, 8 Jul 2015, Julius Werner wrote:

> > But I don't see how you will make it work when the root hub itself is
> > not enabled for wakeup and a non-hub device plugged into one of the
> > root hub's ports is enabled.
> >
> > It seems like you would need a usb_hcd_wakeup_not_needed(hcd, port)
> > subroutine.
> We'd just put that in the Tegra platform driver, I guess. Iterate over
> all ports, call usb_wakeup_enabled_descendants() on the connected
> device (if any) and disable that port's PHY if it returns 0 or wasn't
> connected. Since usb_wakeup_enabled_descendants() also counts
> do_remote_wakeup from the device itself and is safe to call even on
> non-hubs, that should work for all cases.

All right, that seems reasonable.  But remember not to do this if 
wakeup is enabled on the root hub -- in that case all the PHYs must 
remain powered because unplugging and plugging are both wakeup events.

Alan Stern

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