[PATCH 4.3 081/157] usb: core: lpm: fix usb3_hardware_lpm sysfs node

From: Greg Kroah-Hartman
Date: Wed Jan 27 2016 - 13:24:27 EST

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4.3-stable review patch. If anyone has any objections, please let me know.

------------------

From: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>

commit bf5ce5bf3cc7136fd7fe5e8999a580bc93a9c8f6 upstream.

Commit 655fe4effe0f ("usbcore: add sysfs support to xHCI usb3
hardware LPM") introduced usb3_hardware_lpm sysfs node. This
doesn't show the correct status of USB3 U1 and U2 LPM status.

This patch fixes this by replacing usb3_hardware_lpm with two
nodes, usb3_hardware_lpm_u1 (for U1) and usb3_hardware_lpm_u2
(for U2), and recording the U1/U2 LPM status in right places.

This patch should be back-ported to kernels as old as 4.3,
that contains Commit 655fe4effe0f ("usbcore: add sysfs support
to xHCI usb3 hardware LPM").

Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
Documentation/ABI/testing/sysfs-bus-usb | 16 +++++++------
Documentation/usb/power-management.txt | 11 ++++-----
drivers/usb/core/hub.c | 39 ++++++++++++++++++++++++--------
drivers/usb/core/sysfs.c | 31 +++++++++++++++++++++----
include/linux/usb.h | 4 +++
5 files changed, 75 insertions(+), 26 deletions(-)

--- a/Documentation/ABI/testing/sysfs-bus-usb
+++ b/Documentation/ABI/testing/sysfs-bus-usb
@@ -114,19 +114,21 @@ Description:
enabled for the device. Developer can write y/Y/1 or n/N/0 to
the file to enable/disable the feature.

-What: /sys/bus/usb/devices/.../power/usb3_hardware_lpm
-Date: June 2015
+What: /sys/bus/usb/devices/.../power/usb3_hardware_lpm_u1
+ /sys/bus/usb/devices/.../power/usb3_hardware_lpm_u2
+Date: November 2015
Contact: Kevin Strasser <kevin.strasser@xxxxxxxxxxxxxxx>
+ Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
Description:
If CONFIG_PM is set and a USB 3.0 lpm-capable device is plugged
in to a xHCI host which supports link PM, it will check if U1
and U2 exit latencies have been set in the BOS descriptor; if
- the check is is passed and the host supports USB3 hardware LPM,
+ the check is passed and the host supports USB3 hardware LPM,
USB3 hardware LPM will be enabled for the device and the USB
- device directory will contain a file named
- power/usb3_hardware_lpm. The file holds a string value (enable
- or disable) indicating whether or not USB3 hardware LPM is
- enabled for the device.
+ device directory will contain two files named
+ power/usb3_hardware_lpm_u1 and power/usb3_hardware_lpm_u2. These
+ files hold a string value (enable or disable) indicating whether
+ or not USB3 hardware LPM U1 or U2 is enabled for the device.

What: /sys/bus/usb/devices/.../removable
Date: February 2012
--- a/Documentation/usb/power-management.txt
+++ b/Documentation/usb/power-management.txt
@@ -537,17 +537,18 @@ relevant attribute files are usb2_hardwa
can write y/Y/1 or n/N/0 to the file to enable/disable
USB2 hardware LPM manually. This is for test purpose mainly.

- power/usb3_hardware_lpm
+ power/usb3_hardware_lpm_u1
+ power/usb3_hardware_lpm_u2

When a USB 3.0 lpm-capable device is plugged in to a
xHCI host which supports link PM, it will check if U1
and U2 exit latencies have been set in the BOS
descriptor; if the check is is passed and the host
supports USB3 hardware LPM, USB3 hardware LPM will be
- enabled for the device and this file will be created.
- The file holds a string value (enable or disable)
- indicating whether or not USB3 hardware LPM is
- enabled for the device.
+ enabled for the device and these files will be created.
+ The files hold a string value (enable or disable)
+ indicating whether or not USB3 hardware LPM U1 or U2
+ is enabled for the device.

USB Port Power Control
----------------------
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -3886,17 +3886,30 @@ static void usb_enable_link_state(struct
return;
}

- if (usb_set_lpm_timeout(udev, state, timeout))
+ if (usb_set_lpm_timeout(udev, state, timeout)) {
/* If we can't set the parent hub U1/U2 timeout,
* device-initiated LPM won't be allowed either, so let the xHCI
* host know that this link state won't be enabled.
*/
hcd->driver->disable_usb3_lpm_timeout(hcd, udev, state);
+ } else {
+ /* Only a configured device will accept the Set Feature
+ * U1/U2_ENABLE
+ */
+ if (udev->actconfig)
+ usb_set_device_initiated_lpm(udev, state, true);

- /* Only a configured device will accept the Set Feature U1/U2_ENABLE */
- else if (udev->actconfig)
- usb_set_device_initiated_lpm(udev, state, true);
-
+ /* As soon as usb_set_lpm_timeout(timeout) returns 0, the
+ * hub-initiated LPM is enabled. Thus, LPM is enabled no
+ * matter the result of usb_set_device_initiated_lpm().
+ * The only difference is whether device is able to initiate
+ * LPM.
+ */
+ if (state == USB3_LPM_U1)
+ udev->usb3_lpm_u1_enabled = 1;
+ else if (state == USB3_LPM_U2)
+ udev->usb3_lpm_u2_enabled = 1;
+ }
}

/*
@@ -3936,6 +3949,18 @@ static int usb_disable_link_state(struct
dev_warn(&udev->dev, "Could not disable xHCI %s timeout, "
"bus schedule bandwidth may be impacted.\n",
usb3_lpm_names[state]);
+
+ /* As soon as usb_set_lpm_timeout(0) return 0, hub initiated LPM
+ * is disabled. Hub will disallows link to enter U1/U2 as well,
+ * even device is initiating LPM. Hence LPM is disabled if hub LPM
+ * timeout set to 0, no matter device-initiated LPM is disabled or
+ * not.
+ */
+ if (state == USB3_LPM_U1)
+ udev->usb3_lpm_u1_enabled = 0;
+ else if (state == USB3_LPM_U2)
+ udev->usb3_lpm_u2_enabled = 0;
+
return 0;
}

@@ -3970,8 +3995,6 @@ int usb_disable_lpm(struct usb_device *u
if (usb_disable_link_state(hcd, udev, USB3_LPM_U2))
goto enable_lpm;

- udev->usb3_lpm_enabled = 0;
-
return 0;

enable_lpm:
@@ -4029,8 +4052,6 @@ void usb_enable_lpm(struct usb_device *u

usb_enable_link_state(hcd, udev, USB3_LPM_U1);
usb_enable_link_state(hcd, udev, USB3_LPM_U2);
-
- udev->usb3_lpm_enabled = 1;
}
EXPORT_SYMBOL_GPL(usb_enable_lpm);

--- a/drivers/usb/core/sysfs.c
+++ b/drivers/usb/core/sysfs.c
@@ -531,7 +531,7 @@ static ssize_t usb2_lpm_besl_store(struc
}
static DEVICE_ATTR_RW(usb2_lpm_besl);

-static ssize_t usb3_hardware_lpm_show(struct device *dev,
+static ssize_t usb3_hardware_lpm_u1_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct usb_device *udev = to_usb_device(dev);
@@ -539,7 +539,7 @@ static ssize_t usb3_hardware_lpm_show(st

usb_lock_device(udev);

- if (udev->usb3_lpm_enabled)
+ if (udev->usb3_lpm_u1_enabled)
p = "enabled";
else
p = "disabled";
@@ -548,7 +548,26 @@ static ssize_t usb3_hardware_lpm_show(st

return sprintf(buf, "%s\n", p);
}
-static DEVICE_ATTR_RO(usb3_hardware_lpm);
+static DEVICE_ATTR_RO(usb3_hardware_lpm_u1);
+
+static ssize_t usb3_hardware_lpm_u2_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct usb_device *udev = to_usb_device(dev);
+ const char *p;
+
+ usb_lock_device(udev);
+
+ if (udev->usb3_lpm_u2_enabled)
+ p = "enabled";
+ else
+ p = "disabled";
+
+ usb_unlock_device(udev);
+
+ return sprintf(buf, "%s\n", p);
+}
+static DEVICE_ATTR_RO(usb3_hardware_lpm_u2);

static struct attribute *usb2_hardware_lpm_attr[] = {
&dev_attr_usb2_hardware_lpm.attr,
@@ -562,7 +581,8 @@ static struct attribute_group usb2_hardw
};

static struct attribute *usb3_hardware_lpm_attr[] = {
- &dev_attr_usb3_hardware_lpm.attr,
+ &dev_attr_usb3_hardware_lpm_u1.attr,
+ &dev_attr_usb3_hardware_lpm_u2.attr,
NULL,
};
static struct attribute_group usb3_hardware_lpm_attr_group = {
@@ -592,7 +612,8 @@ static int add_power_attributes(struct d
if (udev->usb2_hw_lpm_capable == 1)
rc = sysfs_merge_group(&dev->kobj,
&usb2_hardware_lpm_attr_group);
- if (udev->lpm_capable == 1)
+ if (udev->speed == USB_SPEED_SUPER &&
+ udev->lpm_capable == 1)
rc = sysfs_merge_group(&dev->kobj,
&usb3_hardware_lpm_attr_group);
}
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -507,6 +507,8 @@ struct usb3_lpm_parameters {
* @usb2_hw_lpm_enabled: USB2 hardware LPM is enabled
* @usb2_hw_lpm_allowed: Userspace allows USB 2.0 LPM to be enabled
* @usb3_lpm_enabled: USB3 hardware LPM enabled
+ * @usb3_lpm_u1_enabled: USB3 hardware U1 LPM enabled
+ * @usb3_lpm_u2_enabled: USB3 hardware U2 LPM enabled
* @string_langid: language ID for strings
* @product: iProduct string, if present (static)
* @manufacturer: iManufacturer string, if present (static)
@@ -580,6 +582,8 @@ struct usb_device {
unsigned usb2_hw_lpm_enabled:1;
unsigned usb2_hw_lpm_allowed:1;
unsigned usb3_lpm_enabled:1;
+ unsigned usb3_lpm_u1_enabled:1;
+ unsigned usb3_lpm_u2_enabled:1;
int string_langid;

/* static strings from the device */

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