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Date:   Mon, 6 Nov 2023 11:42:24 +0100
From:   Johan Hovold <johan@kernel.org>
To:     Stanley =?utf-8?B?Q2hhbmdb5piM6IKy5b63XQ==?= 
        <stanley_chang@realtek.com>
Cc:     Stefan Eichenberger <eichest@gmail.com>,
        Johan Hovold <johan+linaro@kernel.org>,
        Mathias Nyman <mathias.nyman@intel.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "stable@vger.kernel.org" <stable@vger.kernel.org>,
        Maxime Ripard <mripard@kernel.org>
Subject: Re: [PATCH] USB: xhci-plat: fix legacy PHY double inity
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On Mon, Nov 06, 2023 at 10:37:06AM +0000, Stanley Chang[昌育德] wrote:

> > > I use drivers/usb/dwc3/core.c and drivers/usb/dwc3/dwc3-rtk.c I
> > > describe the PHY as generic and legacy PHY in device tree.
> > 
> > That's not right. You should just use the generic PHY binding for new platforms.
> > 
> > > Our driver needs the API base on a08799cf17c2 ("usb: phy: add usb phy
> > notify port status API").
> > > But generic PHY driver is not support this.
> > 
> > Yes, but you added that interface yourself, and that I think merging that was a
> > mistake.
> > 
> > We should not be building functionality on top of the legacy USB PHY
> > implementation which is stuck in some transitional limbo.
> > 
> > Apparently, your PHY drivers which were merged for 6.6 are the only users of
> > this interface, and there are no upstream devicetrees that use these PHYs.
> > 
> > I think we should revert this mess before we dig ourselves into an even deeper
> > hole.
> 
> This is an interim method, as the current generic PHY framework does
> not support special operations on USB PHY.

Then you need to add that.

You can't add a new interface which is broken by design and can't be
used unless you abuse the devicetree and describe your PHYs using *both*
the generic 'phy' property and the *deprecated* 'usb-phy' property.

That's just broken.

> Now the generic PHY can't instead USB PHY in this stage.
> For example,
> drivers/phy/ti/phy-twl4030-usb.c
> drivers/phy/qualcomm/phy-qcom-ipq806x-usb.c
> drivers/phy/ti/phy-omap-usb2.c

These should be fixed as well eventually.

Johan