linux-kernel - RE: [PATCH] USB: xhci-plat: fix legacy PHY double inity

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Message-ID: <c85c1f7512524cdf9b452c2c023dc640@realtek.com>
Date:   Tue, 7 Nov 2023 01:16:03 +0000
From:   Stanley Chang[昌育德] 
        <stanley_chang@...ltek.com>
To:     Johan Hovold <johan@...nel.org>
CC:     Stefan Eichenberger <eichest@...il.com>,
        Johan Hovold <johan+linaro@...nel.org>,
        Mathias Nyman <mathias.nyman@...el.com>,
        "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>,
        Maxime Ripard <mripard@...nel.org>
Subject: RE: [PATCH] USB: xhci-plat: fix legacy PHY double inity

Hi Johan,

> 
> 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.

I will modify the Realtek phy to solve this problem and just use the generic PHY.
I don't think this patch on a08799cf17c2 ("usb:phy: New usb phy notification port status API") needs to be reverted.
I will submit fixes based on these patches.

Thanks,
Stanley

> > 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