linux-kernel - Re: [v1 1/1] usb:host:xhci support option to disable xHCI 1.0 USB2 HW LPM

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Date:   Fri, 19 May 2017 10:44:12 +0700
From:   "Thang Q. Nguyen" <tqnguyen@....com>
To:     Rob Herring <robh@...nel.org>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Felipe Balbi <felipe.balbi@...ux.intel.com>,
        Mark Rutland <mark.rutland@....com>,
        Mathias Nyman <mathias.nyman@...el.com>,
        linux-usb@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, Phong Vo <pvo@....com>,
        Loc Ho <lho@....com>, Duc Tran <dxtran@....com>,
        Quang Han <qhan@....com>, Tung Nguyen <tunguyen@....com>,
        patches <patches@....com>
Subject: Re: [v1 1/1] usb:host:xhci support option to disable xHCI 1.0 USB2 HW LPM

On Fri, May 19, 2017 at 5:30 AM, Rob Herring <robh@...nel.org> wrote:
> On Sat, May 13, 2017 at 07:13:14AM +0700, Thang Q. Nguyen wrote:
>> XHCI specification 1.1 does not require xHCI 1.0 compliant controllers
>> to always enable hardware USB2 LPM.
>> However, the current xHCI driver always enable it by setting HLE=1 when
>> seeing HLC=1. This makes certain xHCI controllers that have broken USB2
>> HW LPM fail to work as there is no way to disable this feature.
>> This patch adds support to control disabling USB2 Hardware LPM via
>> DT/ACPI attribute.
>>
>> Signed-off-by: Tung Nguyen <tunguyen@....com>
>> Signed-off-by: Thang Q. Nguyen <tqnguyen@....com>
>> ---
>>  Documentation/devicetree/bindings/usb/usb-xhci.txt |    1 +
>>  drivers/usb/host/xhci-plat.c                       |    3 +++
>>  drivers/usb/host/xhci.c                            |    7 ++++++-
>>  drivers/usb/host/xhci.h                            |    1 +
>>  4 files changed, 11 insertions(+), 1 deletions(-)
>>
>> diff --git a/Documentation/devicetree/bindings/usb/usb-xhci.txt b/Documentation/devicetree/bindings/usb/usb-xhci.txt
>> index 2d80b60..b5da569 100644
>> --- a/Documentation/devicetree/bindings/usb/usb-xhci.txt
>> +++ b/Documentation/devicetree/bindings/usb/usb-xhci.txt
>> @@ -26,6 +26,7 @@ Required properties:
>>
>>  Optional properties:
>>    - clocks: reference to a clock
>> +  - usb2-hle-disable: disable USB2 LPM for hardware does not support it
>>    - usb3-lpm-capable: determines if platform is USB3 LPM capable
>
> Can we have some consistency in the naming of these 2 properties? At
> least use 'lpm' rather than 'hle'. I don't recall why the 2nd one is not
> default enabled, but that would make more sense.
Thanks. I will update the attribute to "usb2-lpm-disable" in the next
patch revision.
>
>>    - quirk-broken-port-ped: set if the controller has broken port disable mechanism
>>