linux-kernel - RE: [PATCH v3 01/19] usb: dwc3: enable hibernation if to be supported

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Message-ID: <A2CA0424C0A6F04399FB9E1CD98E0304844E691D@US01WEMBX2.internal.synopsys.com>
Date:	Tue, 28 Oct 2014 19:15:29 +0000
From:	Paul Zimmerman <Paul.Zimmerman@...opsys.com>
To:	"balbi@...com" <balbi@...com>
CC:	Huang Rui <ray.huang@....com>,
	Alan Stern <stern@...land.harvard.edu>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
	Jason Chang <jason.chang@....com>,
	"Vincent Wan" <vincent.wan@....com>, Tony Li <tony.li@....com>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v3 01/19] usb: dwc3: enable hibernation if to be
 supported

> From: Felipe Balbi [mailto:balbi@...com]
> Sent: Tuesday, October 28, 2014 12:01 PM
> 
> On Tue, Oct 28, 2014 at 06:55:50PM +0000, Paul Zimmerman wrote:
> > > From: Felipe Balbi [mailto:balbi@...com]
> > > Sent: Tuesday, October 28, 2014 11:51 AM
> > >
> > > On Tue, Oct 28, 2014 at 06:47:08PM +0000, Paul Zimmerman wrote:
> > > > > From: Huang Rui [mailto:ray.huang@....com]
> > > > > Sent: Tuesday, October 28, 2014 4:54 AM
> > > > >
> > > > > It enables hibernation if the function is set in coreConsultant.
> > > > >
> > > > > Suggested-by: Felipe Balbi <balbi@...com>
> > > > > Signed-off-by: Huang Rui <ray.huang@....com>
> > > > > ---
> > > > >  drivers/usb/dwc3/core.c | 1 +
> > > > >  1 file changed, 1 insertion(+)
> > > > >
> > > > > diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> > > > > index fa396fc..bf77509 100644
> > > > > --- a/drivers/usb/dwc3/core.c
> > > > > +++ b/drivers/usb/dwc3/core.c
> > > > > @@ -449,6 +449,7 @@ static int dwc3_core_init(struct dwc3 *dwc)
> > > > >  	case DWC3_GHWPARAMS1_EN_PWROPT_HIB:
> > > > >  		/* enable hibernation here */
> > > > >  		dwc->nr_scratch = DWC3_GHWPARAMS4_HIBER_SCRATCHBUFS(hwparams4);
> > > > > +		reg |= DWC3_GCTL_GBLHIBERNATIONEN;
> > > > >  		break;
> > > > >  	default:
> > > > >  		dev_dbg(dwc->dev, "No power optimization available\n");
> > > >
> > > > What effect does this have when the controller is in device mode? I
> > > > expect it will start generating DWC3_DEVICE_EVENT_HIBER_REQ interrupt
> > > > events when this register bit is set. So the dev_WARN_ONCE in
> > > > dwc3_gadget_interrupt() will start firing, I think.
> > >
> > > Ok, so this *has* to wait for proper hibernation support ?
> >
> > Ah, never mind. Since the hibernation event is not enabled in the
> > DEVTEN register, the controller shouldn't generate that event after
> > all. So I think it should be OK. Sorry for the noise.
> 
> do you think it's still nice to have a comment here ?

Maybe something along the lines of "enabling this bit so that host-mode
hibernation will work, device-mode hibernation is not implemented yet"?

-- 
Paul

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