linux-kernel - Re: [PATCH v2 1/2] usb: dwc2: optionally assert phy "full reset" when waking up

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Date:	Mon, 2 Nov 2015 10:12:32 -0600
From:	Rob Herring <robh+dt@...nel.org>
To:	Douglas Anderson <dianders@...omium.org>
Cc:	John Youn <johnyoun@...opsys.com>, Felipe Balbi <balbi@...com>,
	Heiko Stübner <heiko@...ech.de>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	lyz <lyz@...k-chips.com>, wulf <wulf@...k-chips.com>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Paul Zimmerman <paulz@...opsys.com>,
	Gregory Herrero <gregory.herrero@...el.com>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Linux USB List <linux-usb@...r.kernel.org>
Subject: Re: [PATCH v2 1/2] usb: dwc2: optionally assert phy "full reset" when
 waking up

On Fri, Oct 30, 2015 at 3:17 PM, Douglas Anderson <dianders@...omium.org> wrote:
> From: Doug Anderson <dianders@...omium.org>
>
> On the rk3288 USB host-only port (the one that's not the OTG-enabled
> port) the PHY can get into a bad state when a wakeup is asserted (not
> just a wakeup from full system suspend but also a wakeup from
> autosuspend).

I would think re-enumerating means autosuspend is broken.

> We can get the PHY out of its bad state by asserting its "port reset",
> but unfortunately that seems to assert a reset onto the USB bus so it
> could confuse things if we don't actually deenumerate / reenumerate the
> device.
>
> We can also get the PHY out of its bad state by fully resetting it using
> the reset from the CRU (clock reset unit), which does a more full
> reset.  The CRU-based reset appears to actually cause devices on the bus
> to be removed and reinserted, which fixes the problem (albeit in a hacky
> way).

The reset from the CRU goes to the PHY, correct? Therefore, the
binding should reflect that. Connecting it to the host controller is a
hack.

So describe the reset connection properly and then add a .phy_reset()
hook to the phy subsystem. Then call that when flag property you added
is set.

Rob
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