On Tue, Apr 15, 2014 at 01:48:00AM +0800, Paul Zimmerman wrote: > > From: linux-usb-owner@xxxxxxxxxxxxxxx [mailto:linux-usb-owner@xxxxxxxxxxxxxxx] On Behalf Of Pratyush Anand > > Sent: Monday, April 14, 2014 1:48 AM > > > > On Mon, Apr 14, 2014 at 09:42:25AM +0530, Pratyush Anand wrote: > > > Hi Paul, > > > > > > On Sat, Apr 12, 2014 at 02:25:27AM +0800, Paul Zimmerman wrote: > > > > > From: Pratyush Anand [mailto:pratyush.anand@xxxxxxxxx] > > > > > Sent: Friday, April 11, 2014 11:06 AM > > > > > > > > > > On Fri, Apr 11, 2014 at 11:24 PM, Felipe Balbi <balbi@xxxxxx> wrote: > > > > > > On Fri, Apr 11, 2014 at 03:50:03PM +0530, Pratyush Anand wrote: > > > > > >> If a dwc3 host implementation is lpm capable then enable lpm_capable in > > > > > >> device tree. > > > > > >> > > > > > >> Signed-off-by: Pratyush Anand <pratyush.anand@xxxxxx> > > > > > >> --- > > > > > >> Documentation/devicetree/bindings/usb/dwc3.txt | 2 ++ > > > > > >> 1 file changed, 2 insertions(+) > > > > > >> > > > > > >> diff --git a/Documentation/devicetree/bindings/usb/dwc3.txt > > > > > b/Documentation/devicetree/bindings/usb/dwc3.txt > > > > > >> index 7a95c65..a7a48f1 100644 > > > > > >> --- a/Documentation/devicetree/bindings/usb/dwc3.txt > > > > > >> +++ b/Documentation/devicetree/bindings/usb/dwc3.txt > > > > > >> @@ -10,6 +10,7 @@ Required properties: > > > > > >> > > > > > >> Optional properties: > > > > > >> - tx-fifo-resize: determines if the FIFO *has* to be reallocated. > > > > > >> + - lpm-capable: determines if xhci host is lpm capable > > > > > >> > > > > > >> This is usually a subnode to DWC3 glue to which it is connected. > > > > > >> > > > > > >> @@ -19,4 +20,5 @@ dwc3@4a030000 { > > > > > >> interrupts = <0 92 4> > > > > > >> usb-phy = <&usb2_phy>, <&usb3,phy>; > > > > > >> tx-fifo-resize; > > > > > >> + lpm-capable; > > > > > > > > > > > > I think there's a way to detect this in runtime but I can't seem to find > > > > > > it on databook. Perhaps check with your IP designer/integrator which > > > > > > HWPARAMS register we can poke to verify core was configured with LPM ? > > > > > > > > > > I too tried to look into databook first, But could not find. Lets see, what Paul > > > > > says. > > > > > > > > Hi guys, > > > > > > > > The "Power Management" section of the databook talks about hardware- > > > > controlled LPM. It's section 12.4 in the latest databook. LPM is a > > > > standard xHCI feature, so you can look at the xHCI spec to find the > > > > info about it. > > > > > > > > In the xHCI spec, section 4.23.5.1.1 "USB2 LPM Support" says this: > > > > > > > > "This section applies only if a USB2 xHCI Supported Protocol Capability > > > > structure (section 7.2) is declared (i.e. the Major Revision field = 02h)." > > > > > > > > And if you look at section 7.2.2.1.3.2 "USB2", it shows that bit 19 in > > > > the Protocol Defined field of the USB2 xHCI Supported Protocol Capability > > > > structure indicates whether the controller supports hardware-controlled > > > > LPM. > > > > > > Yes, for USB2 LPM we can use it. But These patches are mainly for USB3 > > > LPM where we program U1/U2 inactivity timeout. I am not sure if same > > > bit can be used for USB3 LPM. > > > > It seems for USB3 LPM there is no defined bit available. > > For USB2: > > xhci driver already using the bit you have suggested. > > So for USB3: > > LPM capability info need to be passed from platform. > > I'm am pretty sure there was no DWC3 hardware released to customers > that did not support USB 3.0 link power management. So it should be > safe to assume that it is always supported. Good, then passing the capability from platforms can be removed. So, for all dwc3 xhci host software, LPM will be enabled by default. If a device has the capability in its BOS descriptor then software will enable LPM for that device. Regards Pratyush > > -- > Paul -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
