On Mon, 20 May 2019 10:56:03 -0700, Douglas Anderson wrote: > Some SoCs with a dwc2 USB controller may need to keep the PHY on to > support remote wakeup. Allow specifying this as a device tree > property. > > Signed-off-by: Douglas Anderson <dianders@xxxxxxxxxxxx> > --- > For relevant prior discussion on this patch, see: > > https://lkml.kernel.org/r/1435017144-2971-3-git-send-email-dianders@xxxxxxxxxxxx > > I didn't make any changes from the prior version since I never found > out what Rob thought of my previous arguments. If folks want a > change, perhaps they could choose from these options: > > 1. Assume that all dwc2 hosts would like to keep their PHY on for > suspend if there's a USB wakeup enabled, thus we totally drop this > binding. This doesn't seem super great to me since I'd bet that > many devices that use dwc2 weren't designed for USB wakeup (they > may not keep enough clocks or rails on) so we might be wasting > power for nothing. > 2. Rename this property to "snps,wakeup-from-suspend-with-phy" to make > it more obvious that this property is intended both to document > that wakeup from suspend is possible and that we need the PHY for > said wakeup. > 3. Rename this property to "snps,can-wakeup-from-suspend" and assume > it's implicit that if we can wakeup from suspend that we need to > keep the PHY on. If/when someone shows that a device exists using > dwc2 where we can wakeup from suspend without the PHY they can add > a new property. > > NOTE FOR REPOST: > - In v2 Rob said [1] he'd prefer something based on the SoC > compatibility string, but that doesn't work because not all boards > will have the regulator setup / board design / suspend logic > necessary to make this work. > > [1] https://lkml.kernel.org/r/20190430012328.GA25660@bogus > > > Changes in v3: None > Changes in v2: None > > Documentation/devicetree/bindings/usb/dwc2.txt | 3 +++ > 1 file changed, 3 insertions(+) > Reviewed-by: Rob Herring <robh@xxxxxxxxxx>
