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

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Date:   Sun, 9 Jul 2017 08:16:34 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     "Thang Q. Nguyen" <tqnguyen@....com>
Cc:     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, 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 Sun, Jul 09, 2017 at 12:38:19PM +0700, Thang Q. Nguyen wrote:
> 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?

Relax, it's the middle of the merge window, we can't do anything with
patches until after 4.13-rc1 comes out a the earliest...

greg k-h