4 files changed, 14 insertions, 28 deletions

diff --git a/Documentation/driver-api/usb/power-management.rst b/Documentation/driver-api/usb/power-management.rst
index 79beb807996b..4a74cf6f2797 100644
--- a/Documentation/driver-api/usb/power-management.rst
+++ b/Documentation/driver-api/usb/power-management.rst
@@ -370,11 +370,15 @@ autosuspend the interface's device.  When the usage counter is = 0
 then the interface is considered to be idle, and the kernel may
 autosuspend the device.
 
-Drivers need not be concerned about balancing changes to the usage
-counter; the USB core will undo any remaining "get"s when a driver
-is unbound from its interface.  As a corollary, drivers must not call
-any of the ``usb_autopm_*`` functions after their ``disconnect``
-routine has returned.
+Drivers must be careful to balance their overall changes to the usage
+counter.  Unbalanced "get"s will remain in effect when a driver is
+unbound from its interface, preventing the device from going into
+runtime suspend should the interface be bound to a driver again.  On
+the other hand, drivers are allowed to achieve this balance by calling
+the ``usb_autopm_*`` functions even after their ``disconnect`` routine
+has returned -- say from within a work-queue routine -- provided they
+retain an active reference to the interface (via ``usb_get_intf`` and
+``usb_put_intf``).
 
 Drivers using the async routines are responsible for their own
 synchronization and mutual exclusion.
diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
index 8987cec9549d..ebcadaad89d1 100644
--- a/drivers/usb/core/driver.c
+++ b/drivers/usb/core/driver.c
@@ -473,11 +473,6 @@ static int usb_unbind_interface(struct device *dev)
                 pm_runtime_disable(dev);
         pm_runtime_set_suspended(dev);
 
-        /* Undo any residual pm_autopm_get_interface_* calls */
-        for (r = atomic_read(&intf->pm_usage_cnt); r > 0; --r)
-                usb_autopm_put_interface_no_suspend(intf);
-        atomic_set(&intf->pm_usage_cnt, 0);
-
         if (!error)
                 usb_autosuspend_device(udev);
 
@@ -1633,7 +1628,6 @@ void usb_autopm_put_interface(struct usb_interface *intf)
         int                     status;
 
         usb_mark_last_busy(udev);
-        atomic_dec(&intf->pm_usage_cnt);
         status = pm_runtime_put_sync(&intf->dev);
         dev_vdbg(&intf->dev, "%s: cnt %d -> %d\n",
                         __func__, atomic_read(&intf->dev.power.usage_count),
@@ -1662,7 +1656,6 @@ void usb_autopm_put_interface_async(struct usb_interface *intf)
         int                     status;
 
         usb_mark_last_busy(udev);
-        atomic_dec(&intf->pm_usage_cnt);
         status = pm_runtime_put(&intf->dev);
         dev_vdbg(&intf->dev, "%s: cnt %d -> %d\n",
                         __func__, atomic_read(&intf->dev.power.usage_count),
@@ -1684,7 +1677,6 @@ void usb_autopm_put_interface_no_suspend(struct usb_interface *intf)
         struct usb_device       *udev = interface_to_usbdev(intf);
 
         usb_mark_last_busy(udev);
-        atomic_dec(&intf->pm_usage_cnt);
         pm_runtime_put_noidle(&intf->dev);
 }
 EXPORT_SYMBOL_GPL(usb_autopm_put_interface_no_suspend);
@@ -1715,8 +1707,6 @@ int usb_autopm_get_interface(struct usb_interface *intf)
         status = pm_runtime_get_sync(&intf->dev);
         if (status < 0)
                 pm_runtime_put_sync(&intf->dev);
-        else
-                atomic_inc(&intf->pm_usage_cnt);
         dev_vdbg(&intf->dev, "%s: cnt %d -> %d\n",
                         __func__, atomic_read(&intf->dev.power.usage_count),
                         status);
@@ -1750,8 +1740,6 @@ int usb_autopm_get_interface_async(struct usb_interface *intf)
         status = pm_runtime_get(&intf->dev);
         if (status < 0 && status != -EINPROGRESS)
                 pm_runtime_put_noidle(&intf->dev);
-        else
-                atomic_inc(&intf->pm_usage_cnt);
         dev_vdbg(&intf->dev, "%s: cnt %d -> %d\n",
                         __func__, atomic_read(&intf->dev.power.usage_count),
                         status);
@@ -1775,7 +1763,6 @@ void usb_autopm_get_interface_no_resume(struct usb_interface *intf)
         struct usb_device       *udev = interface_to_usbdev(intf);
 
         usb_mark_last_busy(udev);
-        atomic_inc(&intf->pm_usage_cnt);
         pm_runtime_get_noresume(&intf->dev);
 }
 EXPORT_SYMBOL_GPL(usb_autopm_get_interface_no_resume);
diff --git a/drivers/usb/storage/realtek_cr.c b/drivers/usb/storage/realtek_cr.c
index 31b024441938..cc794e25a0b6 100644
--- a/drivers/usb/storage/realtek_cr.c
+++ b/drivers/usb/storage/realtek_cr.c
@@ -763,18 +763,16 @@ static void rts51x_suspend_timer_fn(struct timer_list *t)
                 break;
         case RTS51X_STAT_IDLE:
         case RTS51X_STAT_SS:
-                usb_stor_dbg(us, "RTS51X_STAT_SS, intf->pm_usage_cnt:%d, power.usage:%d\n",
-                             atomic_read(&us->pusb_intf->pm_usage_cnt),
+                usb_stor_dbg(us, "RTS51X_STAT_SS, power.usage:%d\n",
                              atomic_read(&us->pusb_intf->dev.power.usage_count));
 
-                if (atomic_read(&us->pusb_intf->pm_usage_cnt) > 0) {
+                if (atomic_read(&us->pusb_intf->dev.power.usage_count) > 0) {
                         usb_stor_dbg(us, "Ready to enter SS state\n");
                         rts51x_set_stat(chip, RTS51X_STAT_SS);
                         /* ignore mass storage interface's children */
                         pm_suspend_ignore_children(&us->pusb_intf->dev, true);
                         usb_autopm_put_interface_async(us->pusb_intf);
-                        usb_stor_dbg(us, "RTS51X_STAT_SS 01, intf->pm_usage_cnt:%d, power.usage:%d\n",
-                                     atomic_read(&us->pusb_intf->pm_usage_cnt),
+                        usb_stor_dbg(us, "RTS51X_STAT_SS 01, power.usage:%d\n",
                                      atomic_read(&us->pusb_intf->dev.power.usage_count));
                 }
                 break;
@@ -807,11 +805,10 @@ static void rts51x_invoke_transport(struct scsi_cmnd *srb, struct us_data *us)
         int ret;
 
         if (working_scsi(srb)) {
-                usb_stor_dbg(us, "working scsi, intf->pm_usage_cnt:%d, power.usage:%d\n",
-                             atomic_read(&us->pusb_intf->pm_usage_cnt),
+                usb_stor_dbg(us, "working scsi, power.usage:%d\n",
                              atomic_read(&us->pusb_intf->dev.power.usage_count));
 
-                if (atomic_read(&us->pusb_intf->pm_usage_cnt) <= 0) {
+                if (atomic_read(&us->pusb_intf->dev.power.usage_count) <= 0) {
                         ret = usb_autopm_get_interface(us->pusb_intf);
                         usb_stor_dbg(us, "working scsi, ret=%d\n", ret);
                 }
diff --git a/include/linux/usb.h b/include/linux/usb.h
index 5e49e82c4368..ff010d1fd1c7 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -200,7 +200,6 @@ usb_find_last_int_out_endpoint(struct usb_host_interface *alt,
  * @dev: driver model's view of this device
  * @usb_dev: if an interface is bound to the USB major, this will point
  *      to the sysfs representation for that device.
- * @pm_usage_cnt: PM usage counter for this interface
  * @reset_ws: Used for scheduling resets from atomic context.
  * @resetting_device: USB core reset the device, so use alt setting 0 as
  *      current; needs bandwidth alloc after reset.
@@ -257,7 +256,6 @@ struct usb_interface {
 
         struct device dev;              /* interface specific device info */
         struct device *usb_dev;
-        atomic_t pm_usage_cnt;          /* usage counter for autosuspend */
         struct work_struct reset_ws;    /* for resets in atomic context */
 };
 #define to_usb_interface(d) container_of(d, struct usb_interface, dev)