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Subject: Re: [REPOST PATCH 3/3] USB: dwc2: Don't turn off the usbphy in
 suspend if wakeup is enabled
From: Julius Werner <jwerner@chromium.org>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: Julius Werner <jwerner@chromium.org>, Felipe Balbi <balbi@ti.com>,
        Douglas Anderson <dianders@chromium.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        John Youn <johnyoun@synopsys.com>,
        "linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
        Chris Zhong <zyw@rock-chips.com>, Heiko Stuebner <heiko@sntech.de>,
        Andrew Bresticker <abrestic@chromium.org>,
        Alexandru Stan <amstan@chromium.org>, lyz <lyz@rock-chips.com>,
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        LKML <linux-kernel@vger.kernel.org>
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> 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.