From 2d2a316765d956bc5cb6bb367b2ec52ca59ab8e9 Mon Sep 17 00:00:00 2001 From: Lu Baolu Date: Tue, 16 Jun 2015 09:08:26 +0800 Subject: [PATCH] usb: core: lpm: set lpm_capable for root hub device 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."). Cc: stable@vger.kernel.org # 3.15 Reported-by: Kevin Strasser Signed-off-by: Lu Baolu Acked-by: Alan Stern Signed-off-by: Greg Kroah-Hartman --- 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(-) diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c index be5b2074f906..cbcd0920fb51 100644 --- a/drivers/usb/core/hcd.c +++ b/drivers/usb/core/hcd.c @@ -1022,9 +1022,12 @@ static int register_root_hub(struct usb_hcd *hcd) 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); diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c index 43cb2f2e3b43..73dfa194160b 100644 --- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -122,7 +122,7 @@ struct usb_hub *usb_hub_to_struct_hub(struct usb_device *hdev) 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. diff --git a/drivers/usb/core/usb.h b/drivers/usb/core/usb.h index 7eb1e26798e5..457255a3306a 100644 --- 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 -- 2.39.5