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

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Date:   Wed, 26 Jan 2022 13:25:23 +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 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