usb: host: xhci support option to disable the xHCI USB2 HW LPM

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@apm.com>
Signed-off-by: Thang Q. Nguyen <tqnguyen@apm.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/Documentation/devicetree/bindings/usb/usb-xhci.txt b/Documentation/devicetree/bindings/usb/usb-xhci.txt
index 2d80b60eeabefe54f4f548fd15cb4da6fb7ab912..ae6e484a8d7c5804bb63ab8f347f9b65c34dc92a 100644 (file)
--- 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 163bafde709f79bf52e8e483d6ba6de43125cc48..d0625faee8f7c3a57426d915c28aa6f964ece0b5 100644 (file)
--- a/drivers/usb/host/xhci-plat.c
+++ b/drivers/usb/host/xhci-plat.c
@@ -259,6 +259,9 @@ 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 b2ff1ff1a02faff066374cafdf9fa5b531db5b81..3a8e75f6898f6b0c71b9b296a7830e6aa00c4fda 100644 (file)
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -4087,7 +4087,7 @@ static int xhci_set_usb2_hardware_lpm(struct usb_hcd *hcd,
        xhci_dbg(xhci, "%s port %d USB2 hardware LPM\n",
                        enable ? "enable" : "disable", port_num + 1);
 
-       if (enable) {
+       if (enable && !(xhci->quirks & XHCI_HW_LPM_DISABLE)) {
                /* Host supports BESL timeout instead of HIRD */
                if (udev->usb2_hw_lpm_besl_capable) {
                        /* if device doesn't have a preferred BESL value use a

diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index 2abaa4d6d39daa74ff379020171efaf34a7e9197..dc22392711e32484a4ad43855dfad15de71e5f83 100644 (file)
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -1828,6 +1828,7 @@ struct xhci_hcd {
 #define XHCI_LIMIT_ENDPOINT_INTERVAL_7 (1 << 26)
 #define XHCI_U2_DISABLE_WAKE   (1 << 27)
 #define XHCI_ASMEDIA_MODIFY_FLOWCONTROL        (1 << 28)
+#define XHCI_HW_LPM_DISABLE    (1 << 29)
 
        unsigned int            num_active_eps;
        unsigned int            limit_active_eps;