USB: add usb_hcd_{start,end}_port_resume

This patch (as1649) adds a mechanism for host controller drivers to
inform usbcore when they have begun or ended resume signalling on a
particular root-hub port.  The core will then make sure that the root
hub does not get runtime-suspended while the port resume is going on.

Since commit 596d789a211d134dc5f94d1e5957248c204ef850 (USB: set hub's
default autosuspend delay as 0), the system tries to suspend hubs
whenever they aren't in use.  While a root-hub port is being resumed,
the root hub does not appear to be in use.  Attempted runtime suspends
fail because of the ongoing port resume, but the PM core just keeps on
trying over and over again.  We want to prevent this wasteful effort.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Tested-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2 files changed, 5 insertions, 0 deletions

diff --git a/include/linux/usb.h b/include/linux/usb.h
index 689b14b26c8d..4d22d0f6167a 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -357,6 +357,8 @@ struct usb_bus {
         int bandwidth_int_reqs;         /* number of Interrupt requests */
         int bandwidth_isoc_reqs;        /* number of Isoc. requests */
 
+        unsigned resuming_ports;        /* bit array: resuming root-hub ports */
+
 #if defined(CONFIG_USB_MON) || defined(CONFIG_USB_MON_MODULE)
         struct mon_bus *mon_bus;        /* non-null when associated */
         int monitored;                  /* non-zero when monitored */
diff --git a/include/linux/usb/hcd.h b/include/linux/usb/hcd.h
index 608050b2545f..0a78df5f6cfd 100644
--- a/include/linux/usb/hcd.h
+++ b/include/linux/usb/hcd.h
@@ -430,6 +430,9 @@ extern void usb_hcd_poll_rh_status(struct usb_hcd *hcd);
 extern void usb_wakeup_notification(struct usb_device *hdev,
                 unsigned int portnum);
 
+extern void usb_hcd_start_port_resume(struct usb_bus *bus, int portnum);
+extern void usb_hcd_end_port_resume(struct usb_bus *bus, int portnum);
+
 /* The D0/D1 toggle bits ... USE WITH CAUTION (they're almost hcd-internal) */
 #define usb_gettoggle(dev, ep, out) (((dev)->toggle[out] >> (ep)) & 1)
 #define usb_dotoggle(dev, ep, out)  ((dev)->toggle[out] ^= (1 << (ep)))