Re: [PATCH 2/2] usb: dwc: host: add xhci_plat_priv quirk XHCI_SKIP_PHY_INIT

From: Pavan Kondeti <quic_pkondeti@quicinc.com>
To: Jun Li <lijun.kernel@gmail.com>
Cc: Pavan Kondeti <quic_pkondeti@quicinc.com>,
	Li Jun <jun.li@nxp.com>,
	Sandeep Maheswaram <quic_c_sanm@quicinc.com>,
	Peter Chen <peter.chen@kernel.org>,
	Pawel Laszczak <pawell@cadence.com>,
	Roger Quadros <rogerq@kernel.org>,
	Aswath Govindraju <a-govindraju@ti.com>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	Felipe Balbi <balbi@kernel.org>,
	Mathias Nyman <mathias.nyman@intel.com>,
	Stephen Boyd <swboyd@chromium.org>,
	Doug Anderson <dianders@chromium.org>,
	Matthias Kaehlcke <mka@chromium.org>,
	<linux-arm-msm@vger.kernel.org>,
	Linux USB List <linux-usb@vger.kernel.org>,
	lkml <linux-kernel@vger.kernel.org>, <quic_ppratap@quicinc.com>
Subject: Re: [PATCH 2/2] usb: dwc: host: add xhci_plat_priv quirk XHCI_SKIP_PHY_INIT
Date: Wed, 16 Feb 2022 14:28:31 +0530	[thread overview]
Message-ID: <20220216085831.GA15957@hu-pkondeti-hyd.qualcomm.com> (raw)
In-Reply-To: <CAKgpwJVwTDd40ZR3tKOgVpRTNs1OjE5ssMM+Lj-Ak0CHPSAWQQ@mail.gmail.com>

On Wed, Feb 16, 2022 at 04:49:32PM +0800, Jun Li wrote:
> Pavan Kondeti <quic_pkondeti@quicinc.com> 于2022年2月16日周三 16:00写道：
> >
> > On Wed, Feb 16, 2022 at 03:16:40PM +0800, Jun Li wrote:
> > > Sandeep Maheswaram <quic_c_sanm@quicinc.com> 于2022年2月16日周三 14:58写道：
> > > >
> > > > dwc3 manages PHY by own DRD driver, so skip the management by
> > > > HCD core.
> > > > During runtime suspend phy was not getting suspend because
> > > > runtime_usage value is 2.
> > > >
> > > > Signed-off-by: Sandeep Maheswaram <quic_c_sanm@quicinc.com>
> > > > ---
> > > >  drivers/usb/dwc3/host.c | 15 +++++++++++++++
> > > >  1 file changed, 15 insertions(+)
> > > >
> > > > diff --git a/drivers/usb/dwc3/host.c b/drivers/usb/dwc3/host.c
> > > > index eda8719..4a035a8 100644
> > > > --- a/drivers/usb/dwc3/host.c
> > > > +++ b/drivers/usb/dwc3/host.c
> > > > @@ -13,6 +13,14 @@
> > > >  #include <linux/platform_device.h>
> > > >
> > > >  #include "core.h"
> > > > +#include <linux/usb/hcd.h>
> > > > +#include <linux/usb/xhci-plat.h>
> > > > +#include <linux/usb/xhci-quirks.h>
> > > > +
> > > > +
> > > > +static const struct xhci_plat_priv xhci_plat_dwc3_xhci = {
> > > > +       .quirks = XHCI_SKIP_PHY_INIT,
> > > > +};
> > >
> > > It's better to create this xhci_plat_priv by each dwc3 glue layer,
> > > with that, we can use this priv to pass other flags and possibly
> > > override APIs by each glue driver which may not apply to all dwc3
> > > platforms.
> > >
> >
> > Do you see a need for any glue driver to know about this xHC platform data?
> 
> Yes. I have some xhci quirks which are specifix to NXP iMX platforms.
> 
> > AFAICT, glue driver has no direction connection with the dwc3 core. All
> > the required data is coming from dT on ARM based boards. Adding a private
> > interface between dwc3 core and glue for passing xhci platform data seems
> > to be overkill. If there is a pressing need, why not?
> 
> And looking at xhci_plat_priv members
> 
> -struct xhci_plat_priv {
> -       const char *firmware_name;
> -       unsigned long long quirks;
> -       int (*plat_setup)(struct usb_hcd *);
> -       void (*plat_start)(struct usb_hcd *);
> -       int (*init_quirk)(struct usb_hcd *);
> -       int (*suspend_quirk)(struct usb_hcd *);
> -       int (*resume_quirk)(struct usb_hcd *);
> -};
> 
> Are we going to share the same all those quirks and APIs
> implementation across all dwc3 platforms?
> 
Currently Yes. Thats why I am asking if there is a pressing need to
make this more complex than it needs to be..

Thanks,
Pavan