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-rw-r--r--drivers/usb/core/driver.c11
-rw-r--r--include/linux/usb.h7
2 files changed, 14 insertions, 4 deletions
diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
index d938b2b99e31..eb1d00a3543a 100644
--- a/drivers/usb/core/driver.c
+++ b/drivers/usb/core/driver.c
@@ -1196,9 +1196,14 @@ done:
*
* This is the central routine for suspending USB devices. It calls the
* suspend methods for all the interface drivers in @udev and then calls
- * the suspend method for @udev itself. If an error occurs at any stage,
- * all the interfaces which were suspended are resumed so that they remain
- * in the same state as the device.
+ * the suspend method for @udev itself. When the routine is called in
+ * autosuspend, if an error occurs at any stage, all the interfaces
+ * which were suspended are resumed so that they remain in the same
+ * state as the device, but when called from system sleep, all error
+ * from suspend methods of interfaces and the non-root-hub device itself
+ * are simply ignored, so all suspended interfaces are only resumed
+ * to the device's state when @udev is root-hub and its suspend method
+ * returns failure.
*
* Autosuspend requests originating from a child device or an interface
* driver may be made without the protection of @udev's device lock, but
diff --git a/include/linux/usb.h b/include/linux/usb.h
index 52464fb2389b..8d4bc173d66a 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -976,7 +976,12 @@ struct usbdrv_wrap {
* the "usbfs" filesystem. This lets devices provide ways to
* expose information to user space regardless of where they
* do (or don't) show up otherwise in the filesystem.
- * @suspend: Called when the device is going to be suspended by the system.
+ * @suspend: Called when the device is going to be suspended by the
+ * system either from system sleep or runtime suspend context. The
+ * return value will be ignored in system sleep context, so do NOT
+ * try to continue using the device if suspend fails in this case.
+ * Instead, let the resume or reset-resume routine recover from
+ * the failure.
* @resume: Called when the device is being resumed by the system.
* @reset_resume: Called when the suspended device has been reset instead
* of being resumed.