On Mon, Dec 12, 2016 at 8:00 PM, Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx> wrote: > On 12.12.2016 06:00, Thang Q. Nguyen wrote: >> >> On Sat, Dec 10, 2016 at 4:36 AM, Rob Herring <robh@xxxxxxxxxx> wrote: >>> >>> On Sun, Dec 04, 2016 at 07:42:01PM +0700, Thang Q. Nguyen wrote: >>>> >>>> From: Thang Nguyen <tqnguyen@xxxxxxx> >>>> >>>> As per USB 2.0 link power management addendum ECN, table 1-2, page 4, >>>> device or host initiated via resume signaling; device-initiated resumes >>>> can be optionally enabled/disabled by software. This patch adds support >>>> to control enabling the USB2 RWE feature via DT/ACPI attribute. >>>> >>>> Signed-off-by: Vu Nguyen <vnguyen@xxxxxxx> >>>> Signed-off-by: Thang Nguyen <tqnguyen@xxxxxxx> >>>> --- >>>> Documentation/devicetree/bindings/usb/usb-xhci.txt | 1 + >>>> drivers/usb/host/xhci-plat.c | 3 +++ >>>> drivers/usb/host/xhci.c | 5 ++++- >>>> drivers/usb/host/xhci.h | 1 + >>>> 4 files changed, 9 insertions(+), 1 deletion(-) >>>> >>>> diff --git a/Documentation/devicetree/bindings/usb/usb-xhci.txt >>>> b/Documentation/devicetree/bindings/usb/usb-xhci.txt >>>> index 966885c..9b4cd14 100644 >>>> --- a/Documentation/devicetree/bindings/usb/usb-xhci.txt >>>> +++ b/Documentation/devicetree/bindings/usb/usb-xhci.txt >>>> @@ -25,6 +25,7 @@ Required properties: >>>> >>>> Optional properties: >>>> - clocks: reference to a clock >>>> + - usb2-rwe-disable: disable USB2 LPM Remote Wakeup capable >>> >>> >>> Remote wakeup has been around since USB 1.0 days. Does this need to be >>> USB2 or XHCI specific? >> >> This is XHCI specific. Per XHCI specification 1.1, remote wakeup is >> optional for XHCI 1.0 and required for XHCI 1.1. This patch provides >> ability for software to disable RWE for USB2 in XHCI1.0 controller. > > > I think I understand what's going on. > > USB: > The good old USB2 suspend is called L2. Device enters it after 3ms if > there is no link activity. > If a device can remote wakeup (RWE) it's stated in the descriptor. RWE can > be turned on > of off using standard SET/CLEAR Fature requests > > The LPM L1 USB2 state again is entered with a LPM extended transaction to > avoid the > 3ms wait before powersaving. L1 state is exit can be done with a simialr RWE > as L2 resume. > The RWE from L1 can turned on/off using a bit in the LPM extended > transaction. > > XHCI: > > Specs say that if the device supports RWE we should enable it for LPM L1 > exit as well. > This is done by setting the RWE (LPM L1) bit in PORTPMSC register. This bit > only affect LPM L1 remote > wake. see 4.23.5.1.1.1 > > The issue might be that xhci driver never check if the device actually > supports RWE, we always > set the PORTPMSC RWE (for LPM L1) bit. Yes, we should check if device support Remote Wakeup to enable or disable RWE as noted in cases 1 (page 265) and 2 (page 266) from 4.23.5.1.1.1. > > How about checking something like udev->do_remote_wakeup and setting and > setting the bit > based on that. > > The function that you are changing, xhci_set_usb2_hardware_lpm() should > only be used if > host has Hardware LPM Cabaility bit (HLC) set for that USB2 port in the > USB 2.0 xHCI Supported Protocol Capability. > Host that don't supprt LPM won't have that set. See xhci 7.2.2.1.3.2 When hosts support Hardware LPM (HLC), any problem if we add a DT/ACPI attribute to support disable it (HLE=0)? > -Mathias > > > > > > > -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
