Merge branch 'linux-3.18.y' of git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable into linux-linaro-lsk-v3.18lsk-v3.18-15.05

* 'linux-3.18.y' of git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable: (222 commits)
  Linux 3.18.14
  Drivers: hv: vmbus: Don't wait after requesting offers
  hfsplus: don't store special "osx" xattr prefix on-disk
  drm/radeon: check new address before removing old one
  drm/radeon: add SI DPM quirk for Sapphire R9 270 Dual-X 2G GDDR5
  drm/radeon: adjust pll when audio is not enabled
  3w-sas: fix command completion race
  3w-9xxx: fix command completion race
  3w-xxxx: fix command completion race
  ext4: move check under lock scope to close a race.
  ext4: fix data corruption caused by unwritten and delayed extents
  uas: Set max_sectors_240 quirk for ASM1053 devices
  uas: Add US_FL_MAX_SECTORS_240 flag
  uas: Allow uas_use_uas_driver to return usb-storage flags
  rbd: end I/O the entire obj_request on error
  tty/serial: at91: maxburst was missing for dma transfers
  ACPI / SBS: Enable battery manager when present
  btrfs: unlock i_mutex after attempting to delete subvolume during send
  ASoC: rt5677: fixed wrong DMIC ref clock
  ASoC: dapm: Enable autodisable on SOC_DAPM_SINGLE_TLV_AUTODISABLE
  ...

1 files changed, 26 insertions, 0 deletions

diff --git a/include/linux/usb.h b/include/linux/usb.h
index 3827bffc11a7..bdbd19fb1ff8 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -205,6 +205,32 @@ void usb_put_intf(struct usb_interface *intf);
 #define USB_MAXINTERFACES	32
 #define USB_MAXIADS		(USB_MAXINTERFACES/2)
 
+/*
+ * USB Resume Timer: Every Host controller driver should drive the resume
+ * signalling on the bus for the amount of time defined by this macro.
+ *
+ * That way we will have a 'stable' behavior among all HCDs supported by Linux.
+ *
+ * Note that the USB Specification states we should drive resume for *at least*
+ * 20 ms, but it doesn't give an upper bound. This creates two possible
+ * situations which we want to avoid:
+ *
+ * (a) sometimes an msleep(20) might expire slightly before 20 ms, which causes
+ * us to fail USB Electrical Tests, thus failing Certification
+ *
+ * (b) Some (many) devices actually need more than 20 ms of resume signalling,
+ * and while we can argue that's against the USB Specification, we don't have
+ * control over which devices a certification laboratory will be using for
+ * certification. If CertLab uses a device which was tested against Windows and
+ * that happens to have relaxed resume signalling rules, we might fall into
+ * situations where we fail interoperability and electrical tests.
+ *
+ * In order to avoid both conditions, we're using a 40 ms resume timeout, which
+ * should cope with both LPJ calibration errors and devices not following every
+ * detail of the USB Specification.
+ */
+#define USB_RESUME_TIMEOUT	40 /* ms */
+
 /**
  * struct usb_interface_cache - long-term representation of a device interface
  * @num_altsetting: number of altsettings defined.