linux-kernel - Re: [PATCH v9 1/5] usb: host: xhci: plat: Add suspend quirk for dwc3 controller

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Date:   Mon, 1 Nov 2021 14:05:19 -0700
From:   Matthias Kaehlcke <mka@...omium.org>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     Sandeep Maheswaram <quic_c_sanm@...cinc.com>,
        Andy Gross <agross@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Felipe Balbi <balbi@...nel.org>,
        Stephen Boyd <swboyd@...omium.org>,
        Doug Anderson <dianders@...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 v9 1/5] usb: host: xhci: plat: Add suspend quirk for dwc3
 controller

On Mon, Nov 01, 2021 at 01:50:31PM -0700, Bjorn Andersson wrote:
> On Mon 01 Nov 11:59 PDT 2021, Matthias Kaehlcke wrote:
> 
> > Hi Sandeep,
> > 
> > On Mon, Nov 01, 2021 at 01:23:40PM +0530, Sandeep Maheswaram wrote:
> > > During suspend check if any wakeup capable devices are connected to the
> > > controller (directly or through hubs), and set the wakeup capable property
> > > for xhci plat device.
> > > 
> > > Signed-off-by: Sandeep Maheswaram <quic_c_sanm@...cinc.com>
> > > ---
> > >  drivers/usb/host/xhci-plat.c | 12 ++++++++++++
> > >  1 file changed, 12 insertions(+)
> > > 
> > > diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c
> > > index c1edcc9..7ab272b 100644
> > > --- a/drivers/usb/host/xhci-plat.c
> > > +++ b/drivers/usb/host/xhci-plat.c
> > > @@ -431,6 +431,14 @@ static int xhci_plat_remove(struct platform_device *dev)
> > >  	return 0;
> > >  }
> > >  
> > > +static void xhci_dwc3_suspend_quirk(struct usb_hcd *hcd, struct device *dev)
> > > +{
> > > +	if (usb_wakeup_enabled_descendants(hcd->self.root_hub))
> > > +		device_set_wakeup_capable(dev, true);
> > > +	else
> > > +		device_set_wakeup_capable(dev, false);
> > 
> > IIUC wakeup capability is typically a static property that reflects the
> > actual hardware (or firmware) support for wakeup. In that sense it doesn't
> > seem a good idea to change it dynamically at suspend time, depending on
> > what is connected to the bus. I understand though that the odd split
> > of the dwc3 driver makes it hard to do things properly ...
> > 
> > Earlier in this discussion Felipe suggested to add a function like
> > device_children_wakeup_capable(), to avoid having to call
> > usb_wakeup_enabled_descendants() from the dwc3 drivers.
> > 
> > Below is an initial implementation for device_children_wakeup_capable(),
> > could you try if calling it from dwc3_suspend/resume_common() and
> > dwc3_qcom_suspend() would work instead of relying on the wakeup
> > capability?
> > 
> > Thanks
> > 
> > Matthias
> > 
> > From 97c838334045ed67c3943f8e035ac70acd12b89b Mon Sep 17 00:00:00 2001
> > From: Matthias Kaehlcke <mka@...omium.org>
> > Date: Mon, 1 Nov 2021 11:37:19 -0700
> > Subject: [PATCH] PM / wakeup: Add device_children_wakeup_capable()
> > 
> > Add device_children_wakeup_capable() which checks whether the device itself
> > or one if its descendants is wakeup capable.
> > 
> > Change-Id: Ib359eb5ac8650ddf9889c7d1f77707f50777fe99
> > Suggested-by: Felipe Balbi <balbi@...nel.org>
> > Signed-off-by: Matthias Kaehlcke <mka@...omium.org>
> 
> Looks neat and useful.
> 
> Reviewed-by: Bjorn Andersson <bjorn.andersson@...aro.org>

Thanks!

> (Without the Change-Id of course...)

Sure, I usually use patman to send patches upstream, which filters the
Change-Id if present, forgot to remove it when copying and pasting the
patch manually.