linux-kernel - RE: [PATCH v3] usb: chipidea: Grab the (legacy) USB PHY by phandle first

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Date:   Thu, 21 Feb 2019 09:30:47 +0000
From:   Peter Chen <peter.chen@....com>
To:     Paul Kocialkowski <paul.kocialkowski@...tlin.com>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: RE: [PATCH v3] usb: chipidea: Grab the (legacy) USB PHY by phandle
 first

 
> > Current code w/o your patch, it is possible both ci->phy and
> > ci->usb_phy are valid if the USB PHY is not at the device tree, but generic PHY is
> at the device tree.
> > If you don't want to fix this issue with this patch, it is ok too. We could fix it later.
> 
> I'm not sure I understand the issue. With my patch, if there is a generic PHY
> described in device-tree, then devm_usb_get_phy_by_phandle for legacy PHY will
> fail and the code will fallback to devm_usb_get_phy, which is the same behavior as
> before.
> 

You are right, but this behavior is incorrect since each controller has only one physical
USB PHY.

> Is it a problem that we can end up with both a generic and legacy PHY?
> I thought this was expected behavior at probe, and the rest of the code will just use
> the generic one in priority.
> 
> Do you want to make it so that only one (generic or legacy) PHY remains after
> probe?
> 
 
Yes, I just want only one valid, either ci->phy or ci->usb_phy, it makes sense.

Peter