linux-kernel - Re: [PATCH v3 1/1] usb:host:xhci support option to disable the xHCI USB2 HW LPM

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Message-ID: <CAKrQpStT1=93XOA2u-W9nSMX0r0OPhixjMsRbmBO-5UW_k5FOw@mail.gmail.com>
Date:   Sun, 9 Jul 2017 12:38:19 +0700
From:   "Thang Q. Nguyen" <tqnguyen@....com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Rob Herring <robh+dt@...nel.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
Cc:     Thang Nguyen <tqnguyen@....com>, Phong Vo <pvo@....com>,
        Loc Ho <lho@....com>, Tung Nguyen <tunguyen@....com>,
        patches <patches@....com>
Subject: Re: [PATCH v3 1/1] usb:host:xhci support option to disable the xHCI
 USB2 HW LPM

On Fri, Jun 23, 2017 at 10:02 AM, Thang Q. Nguyen <tqnguyen@....com> 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 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 +
>  drivers/usb/host/xhci-plat.c                       |    3 +++
>  drivers/usb/host/xhci.c                            |    3 +++
>  drivers/usb/host/xhci.h                            |    1 +
>  4 files changed, 8 insertions(+), 0 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/usb/usb-xhci.txt b/Documentation/devicetree/bindings/usb/usb-xhci.txt
> index 2d80b60..ae6e484 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-lpm-disable: indicate if we don't want to enable USB2 HW LPM
>    - usb3-lpm-capable: determines if platform is USB3 LPM capable
>    - quirk-broken-port-ped: set if the controller has broken port disable mechanism
>
> diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c
> index c04144b..9028fb5 100644
> --- a/drivers/usb/host/xhci-plat.c
> +++ b/drivers/usb/host/xhci-plat.c
> @@ -267,6 +267,9 @@ static int xhci_plat_probe(struct platform_device *pdev)
>                 goto disable_clk;
>         }
>
> +       if (device_property_read_bool(sysdev, "usb2-lpm-disable"))
> +               xhci->quirks |= XHCI_HW_LPM_DISABLE;
> +
>         if (device_property_read_bool(sysdev, "usb3-lpm-capable"))
>                 xhci->quirks |= XHCI_LPM_SUPPORT;
>
> diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
> index 30f47d9..49d05c7 100644
> --- a/drivers/usb/host/xhci.c
> +++ b/drivers/usb/host/xhci.c
> @@ -4061,6 +4061,9 @@ static int xhci_set_usb2_hardware_lpm(struct usb_hcd *hcd,
>                         !udev->lpm_capable)
>                 return -EPERM;
>
> +       if (xhci->quirks & XHCI_HW_LPM_DISABLE)
> +               return -EPERM;
> +
>         if (!udev->parent || udev->parent->parent ||
>                         udev->descriptor.bDeviceClass == USB_CLASS_HUB)
>                 return -EPERM;
> diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
> index 73a28a9..03d50e8 100644
> --- a/drivers/usb/host/xhci.h
> +++ b/drivers/usb/host/xhci.h
> @@ -1819,6 +1819,7 @@ struct xhci_hcd {
>  /* For controller with a broken Port Disable implementation */
>  #define XHCI_BROKEN_PORT_PED   (1 << 25)
>  #define XHCI_LIMIT_ENDPOINT_INTERVAL_7 (1 << 26)
> +#define XHCI_HW_LPM_DISABLE    (1 << 27)
>
>         unsigned int            num_active_eps;
>         unsigned int            limit_active_eps;
> --
> 1.7.1
>
Hi,
Is there any other comment on the patch?

Regards,
Thang Q. Nguyen