linux-kernel - Re: [PATCH v4 1/1] usb:host:xhci support option to disable the xHCI USB2 HW LPM

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Message-ID: <20170714143449.hr3eajqywafl4v3r@rob-hp-laptop>
Date:   Fri, 14 Jul 2017 09:34:50 -0500
From:   Rob Herring <robh@...nel.org>
To:     "Thang Q. Nguyen" <tqnguyen@....com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        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>, Tung Nguyen <tunguyen@....com>,
        patches@....com
Subject: Re: [PATCH v4 1/1] usb:host:xhci support option to disable the xHCI
 USB2 HW LPM

On Wed, Jul 12, 2017 at 03:06:48PM +0700, Thang Q. Nguyen wrote:
> XHCI specification 1.1 does not require xHCI-compliant controllers
> to always enable hardware USB2 LPM. However, the current xHCI
> driver always enable it when seeing HLC=1.
> This patch supports an option for users to control disabling
> USB2 Hardware LPM via DT/ACPI attribute.
> This option is needed in case user would like to disable this
> feature. For example, their xHCI controller has its USB2 HW LPM
> broken.
> 
> Signed-off-by: Tung Nguyen <tunguyen@....com>
> Signed-off-by: Thang Q. Nguyen <tqnguyen@....com>
> ---
> Changes since v3:
>  - Bypass updating LPM parameters when HW LPM is optionally disabled.
> Changes since v2:
>  - Change code to disable HW LPM as an option for user which
>    is set via ACPI/DT.
> Changes since v1:
>  - Update DT/ACPI attribute and corresponding codes from HLE to LPM to
>    be consistent with other attribute names.
> ---
>  Documentation/devicetree/bindings/usb/usb-xhci.txt |    1 +

I acked v3. Please add acks when posting new versions.

>  drivers/usb/host/xhci-plat.c                       |    3 +++
>  drivers/usb/host/xhci.c                            |    6 ++++++
>  drivers/usb/host/xhci.h                            |    1 +
>  4 files changed, 11 insertions(+), 0 deletions(-)