This is a note to let you know that I've just added the patch titled
usb: core: lpm: set lpm_capable for root hub device
to the 4.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
usb-core-lpm-set-lpm_capable-for-root-hub-device.patch
and it can be found in the queue-4.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 2d2a316765d956bc5cb6bb367b2ec52ca59ab8e9 Mon Sep 17 00:00:00 2001
From: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
Date: Tue, 16 Jun 2015 09:08:26 +0800
Subject: usb: core: lpm: set lpm_capable for root hub device
From: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
commit 2d2a316765d956bc5cb6bb367b2ec52ca59ab8e9 upstream.
Commit 25cd2882e2fc ("usb/xhci: Change how we indicate a host supports
Link PM.") removed the code to set lpm_capable for USB 3.0 super-speed
root hub. The intention of that change was to avoid touching usb core
internal field, a.k.a. lpm_capable, and let usb core to set it by
checking U1 and U2 exit latency values in the descriptor.
Usb core checks and sets lpm_capable in hub_port_init(). Unfortunately,
root hub is a special usb device as it has no parent. Hub_port_init()
will never be called for a root hub device. That means lpm_capable will
by no means be set for the root hub. As the result, lpm isn't functional
at all in Linux kernel.
This patch add the code to check and set lpm_capable when registering a
root hub device. It could be back-ported to kernels as old as v3.15,
that contains the Commit 25cd2882e2fc ("usb/xhci: Change how we indicate
a host supports Link PM.").
Reported-by: Kevin Strasser <kevin.strasser@xxxxxxxxxxxxxxx>
Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/usb/core/hcd.c | 7 +++++--
drivers/usb/core/hub.c | 2 +-
drivers/usb/core/usb.h | 1 +
3 files changed, 7 insertions(+), 3 deletions(-)
--- a/drivers/usb/core/hcd.c
+++ b/drivers/usb/core/hcd.c
@@ -1022,9 +1022,12 @@ static int register_root_hub(struct usb_
dev_name(&usb_dev->dev), retval);
return (retval < 0) ? retval : -EMSGSIZE;
}
- if (usb_dev->speed == USB_SPEED_SUPER) {
+
+ if (le16_to_cpu(usb_dev->descriptor.bcdUSB) >= 0x0201) {
retval = usb_get_bos_descriptor(usb_dev);
- if (retval < 0) {
+ if (!retval) {
+ usb_dev->lpm_capable = usb_device_supports_lpm(usb_dev);
+ } else if (usb_dev->speed == USB_SPEED_SUPER) {
mutex_unlock(&usb_bus_list_lock);
dev_dbg(parent_dev, "can't read %s bos descriptor %d\n",
dev_name(&usb_dev->dev), retval);
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -122,7 +122,7 @@ struct usb_hub *usb_hub_to_struct_hub(st
return usb_get_intfdata(hdev->actconfig->interface[0]);
}
-static int usb_device_supports_lpm(struct usb_device *udev)
+int usb_device_supports_lpm(struct usb_device *udev)
{
/* USB 2.1 (and greater) devices indicate LPM support through
* their USB 2.0 Extended Capabilities BOS descriptor.
--- a/drivers/usb/core/usb.h
+++ b/drivers/usb/core/usb.h
@@ -65,6 +65,7 @@ extern int usb_hub_init(void);
extern void usb_hub_cleanup(void);
extern int usb_major_init(void);
extern void usb_major_cleanup(void);
+extern int usb_device_supports_lpm(struct usb_device *udev);
#ifdef CONFIG_PM
Patches currently in stable-queue which might be from baolu.lu@xxxxxxxxxxxxxxx are
queue-4.1/usb-core-lpm-set-lpm_capable-for-root-hub-device.patch
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