linux-kernel - Re: [PATCH v2] usb: host: xhci-plat: fix support for XHCI_SKIP_PHY

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Message-ID: <20210113232057.niqamgsqlaw7gojw@pali>
Date:   Thu, 14 Jan 2021 00:20:57 +0100
From:   Pali Rohár <pali@...nel.org>
To:     Peter Chen <peter.chen@....com>
Cc:     Mathias Nyman <mathias.nyman@...el.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jun Li <jun.li@....com>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] usb: host: xhci-plat: fix support for
 XHCI_SKIP_PHY_INIT quirk

On Thursday 24 December 2020 05:59:05 Peter Chen wrote:
> On 20-12-23 17:18:47, Pali Rohár wrote:
> > Currently init_quirk callbacks for xhci platform drivers are called
> > xhci_plat_setup() function which is called after chip reset completes.
> > It happens in the middle of the usb_add_hcd() function.
> > 
> > But XHCI_SKIP_PHY_INIT quirk is checked in the xhci_plat_probe() function
> > prior calling usb_add_hcd() function. Therefore this XHCI_SKIP_PHY_INIT
> > currently does nothing as prior xhci_plat_setup() it is not set.
> > 
> > Quirk XHCI_SKIP_PHY_INIT is only setting hcd->skip_phy_initialization value
> > which really needs to be set prior calling usb_add_hcd() as this function
> > at its beginning skips PHY init if this member is set.
> > 
> > This patch fixes implementation of the XHCI_SKIP_PHY_INIT quirk by calling
> > init_quirk callbacks (via xhci_priv_init_quirk()) prior checking if
> > XHCI_SKIP_PHY_INIT is set. Also checking if either xhci->quirks or
> > priv->quirks contains this XHCI_SKIP_PHY_INIT quirk.
> > 
> > Signed-off-by: Pali Rohár <pali@...nel.org>
> > 
> > ---
> > Changes in v2:
> > * Check also xhci->quirks as xhci_priv_init_quirk() callbacks are setting xhci->quirks
> > * Tested with "usb: host: xhci: mvebu: make USB 3.0 PHY optional for Armada 3720" patch
> > * Removed Fixes: line
> > ---
> >  drivers/usb/host/xhci-plat.c | 16 ++++++++--------
> >  1 file changed, 8 insertions(+), 8 deletions(-)
> > 
> > diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c
> > index 4d34f6005381..0eab7cb5a767 100644
> > --- a/drivers/usb/host/xhci-plat.c
> > +++ b/drivers/usb/host/xhci-plat.c
> > @@ -89,13 +89,6 @@ static void xhci_plat_quirks(struct device *dev, struct xhci_hcd *xhci)
> >  /* called during probe() after chip reset completes */
> >  static int xhci_plat_setup(struct usb_hcd *hcd)
> >  {
> > -	int ret;
> > -
> > -
> > -	ret = xhci_priv_init_quirk(hcd);
> > -	if (ret)
> > -		return ret;
> > -
> >  	return xhci_gen_setup(hcd, xhci_plat_quirks);
> >  }
> >  
> > @@ -330,7 +323,14 @@ static int xhci_plat_probe(struct platform_device *pdev)
> >  
> >  	hcd->tpl_support = of_usb_host_tpl_support(sysdev->of_node);
> >  	xhci->shared_hcd->tpl_support = hcd->tpl_support;
> > -	if (priv && (priv->quirks & XHCI_SKIP_PHY_INIT))
> > +
> > +	if (priv) {
> > +		ret = xhci_priv_init_quirk(hcd);
> > +		if (ret)
> > +			goto disable_usb_phy;
> > +	}
> > +
> > +	if ((xhci->quirks & XHCI_SKIP_PHY_INIT) || (priv && (priv->quirks & XHCI_SKIP_PHY_INIT)))
> >  		hcd->skip_phy_initialization = 1;
> 
> I am not sure if others agree with you move the position of
> xhci_priv_init_quirk, Let's see Mathias opinion.

Hello! Do you have an opinion how to handle this issue? As currently it
is needed for another patch which is fixing issue/regression in xhci-mvebu:
https://lore.kernel.org/linux-usb/20201223162403.10897-1-pali@kernel.org/