linux-kernel - Re: [PATCH v5] usb: host: xhci-plat: Set XHCI_SKIP_PHY

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Message-ID: <YgJB6bGm/y7C0oo/@kroah.com>
Date:   Tue, 8 Feb 2022 11:11:53 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Sandeep Maheswaram <quic_c_sanm@...cinc.com>
Cc:     Felipe Balbi <balbi@...nel.org>,
        Stephen Boyd <swboyd@...omium.org>,
        Doug Anderson <dianders@...omium.org>,
        Matthias Kaehlcke <mka@...omium.org>,
        Mathias Nyman <mathias.nyman@...el.com>,
        linux-arm-msm@...r.kernel.org, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org, quic_pkondeti@...cinc.com,
        quic_ppratap@...cinc.com
Subject: Re: [PATCH v5] usb: host: xhci-plat: Set XHCI_SKIP_PHY_INIT quirk
 for DWC3 controller

On Tue, Feb 08, 2022 at 03:34:22PM +0530, Sandeep Maheswaram wrote:
> Hi Greg,
> 
> On 1/27/2022 10:28 AM, Sandeep Maheswaram wrote:
> > 
> > On 1/26/2022 5:55 PM, Greg Kroah-Hartman wrote:
> > > On Fri, Jan 07, 2022 at 10:27:59AM +0530, Sandeep Maheswaram wrote:
> > > > On 1/6/2022 7:55 PM, Greg Kroah-Hartman wrote:
> > > > > On Wed, Dec 22, 2021 at 11:39:43AM +0530, Sandeep Maheswaram wrote:
> > > > > > Set XHCI_SKIP_PHY_INIT quirk to avoid phy initialization twice.
> > > > > > Runtime suspend of phy drivers was failing from DWC3
> > > > > > driver as runtime
> > > > > > usage value is 2 because the phy is initialized from
> > > > > > DWC3 and HCD core.
> > > > > > DWC3 manages phy in their core drivers. Set this quirk to avoid phy
> > > > > > initialization in HCD core.
> > > > > > 
> > > > > > Signed-off-by: Sandeep Maheswaram <quic_c_sanm@...cinc.com>
> > > > > > ---
> > > > > > v5:
> > > > > > Added comment to explain the change done.
> > > > > > v4:
> > > > > > Changed pdev->dev.parent->of_node to sysdev->of_node
> > > > > > 
> > > > > >    drivers/usb/host/xhci-plat.c | 8 ++++++++
> > > > > >    1 file changed, 8 insertions(+)
> > > > > > 
> > > > > > diff --git a/drivers/usb/host/xhci-plat.c
> > > > > > b/drivers/usb/host/xhci-plat.c
> > > > > > index c1edcc9..e6014d4 100644
> > > > > > --- a/drivers/usb/host/xhci-plat.c
> > > > > > +++ b/drivers/usb/host/xhci-plat.c
> > > > > > @@ -327,6 +327,14 @@ static int xhci_plat_probe(struct
> > > > > > platform_device *pdev)
> > > > > >                         &xhci->imod_interval);
> > > > > >        }
> > > > > > +    /*
> > > > > > +     * Set XHCI_SKIP_PHY_INIT quirk to avoid phy
> > > > > > initialization twice.
> > > > > > +     * DWC3 manages phy in their core drivers. Set this
> > > > > > quirk to avoid phy
> > > > > > +     * initialization in HCD core.
> > > > > > +     */
> > > > > > +    if (of_device_is_compatible(sysdev->of_node, "snps,dwc3"))
> > > > > > +        xhci->quirks |= XHCI_SKIP_PHY_INIT;
> > > > > > +
> > > > > Why is this function caring about dwc3 stuff?  Shoudn't this be a
> > > > > "generic" device property instead of this device-specific one?
> > > > > 
> > > > > thanks,
> > > > > 
> > > > > greg k-h
> > > > This quirk is set only if required for some controllers (eg:
> > > > dwc3 & cdns3).
> > > > 
> > > > Please check below commit.
> > > > 
> > > > https://lore.kernel.org/all/20200918131752.16488-5-mathias.nyman@linux.intel.com/
> > > > 
> > > That commit has nothing to do with a specific "dwc3" quirk anywhere.
> > > Why not set this flag in the specific platform xhci driver instead where
> > > it belongs?
> > > 
> > > thanks,
> > > 
> > > greg k-h
> > 
> > There is no specific xhci platform driver for dwc3 controllers.
> > 
> > dwc3 controllers use xhci-plat driver .
> > 
> > We can add this quirk in usb/dwc3/host.c as cdns3 does but that requires
> > tying dwc3 and xhci driver .
> > 
> > https://patchwork.kernel.org/project/linux-arm-msm/patch/1633946518-13906-1-git-send-email-sanm@codeaurora.org/
> > 
> > 
> > Regards
> > 
> > Sandeep
> > 
> > 
> Can you suggest any other method to set this quirk for dwc3 controllers.

No idea, sorry.