linux-kernel - Re: usb:xhci: support disable usb2 LPM Remote Wakeup

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Date:   Mon, 12 Dec 2016 10:37:58 +0200
From:   Felipe Balbi <felipe.balbi@...ux.intel.com>
To:     "Thang Q. Nguyen" <tqnguyen@....com>, Rob Herring <robh@...nel.org>
Cc:     Pawel Moll <pawel.moll@....com>,
        Mark Rutland <mark.rutland@....com>,
        Ian Campbell <ijc+devicetree@...lion.org.uk>,
        Kumar Gala <galak@...eaurora.org>,
        Mathias Nyman <mathias.nyman@...el.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-usb@...r.kernel.org, Phong Vo <pvo@....com>,
        Loc Ho <lho@....com>, Vu Nguyen <vnguyen@....com>,
        patches <patches@....com>
Subject: Re: usb:xhci: support disable usb2 LPM Remote Wakeup


Hi,

"Thang Q. Nguyen" <tqnguyen@....com> writes:
> On Sat, Dec 10, 2016 at 4:36 AM, Rob Herring <robh@...nel.org> wrote:
>> On Sun, Dec 04, 2016 at 07:42:01PM +0700, Thang Q. Nguyen wrote:
>>> From: Thang Nguyen <tqnguyen@....com>
>>>
>>> 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@....com>
>>> Signed-off-by: Thang Nguyen <tqnguyen@....com>
>>> ---
>>>  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.

is there no way of detecting this in runtime?

-- 
balbi

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