Patch "USB: add quirk for devices with broken LPM" has been added to the 4.3-stable tree

This is a note to let you know that I've just added the patch titled

USB: add quirk for devices with broken LPM

to the 4.3-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
usb-add-quirk-for-devices-with-broken-lpm.patch
and it can be found in the queue-4.3 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Alan Stern <[email protected]>
Date: Thu, 10 Dec 2015 15:27:21 -0500
Subject: USB: add quirk for devices with broken LPM

From: Alan Stern <[email protected]>

commit ad87e03213b552a5c33d5e1e7a19a73768397010 upstream.

Some USB device / host controller combinations seem to have problems with Link Power Management. For example, Steinar found that his xHCI controller wouldn't handle bandwidth calculations correctly for two video cards simultaneously when LPM was enabled, even though the bus had plenty of bandwidth available.

This patch introduces a new quirk flag for devices that should remain disabled for LPM, and creates quirk entries for Steinar's devices.

---
 drivers/usb/core/hub.c     |    7 ++++++-
 drivers/usb/core/quirks.c  |    6 ++++++
 include/linux/usb/quirks.h |    3 +++
 3 files changed, 15 insertions(+), 1 deletion(-)

@@ -124,6 +124,10 @@ struct usb_hub *usb_hub_to_struct_hub(st
 
 int usb_device_supports_lpm(struct usb_device *udev)
 {
+	/* Some devices have trouble with LPM */
+	if (udev->quirks & USB_QUIRK_NO_LPM)
+		return 0;
+
 	/* USB 2.1 (and greater) devices indicate LPM support through
 	 * their USB 2.0 Extended Capabilities BOS descriptor.
 	 */

@@ -4503,6 +4507,8 @@ hub_port_init (struct usb_hub *hub, stru
 		goto fail;
 	}
 
+	usb_detect_quirks(udev);
+
 	if (udev->wusb == 0 && le16_to_cpu(udev->descriptor.bcdUSB) >= 0x0201) {
 		retval = usb_get_bos_descriptor(udev);
 		if (!retval) {

@@ -4701,7 +4707,6 @@ static void hub_port_connect(struct usb_
 		if (status < 0)
 			goto loop;
 
-		usb_detect_quirks(udev);
 		if (udev->quirks & USB_QUIRK_DELAY_INIT)
 			msleep(1000);
 

@@ -199,6 +199,12 @@ static const struct usb_device_id usb_qu
 	{ USB_DEVICE(0x1a0a, 0x0200), .driver_info =
 			USB_QUIRK_LINEAR_UFRAME_INTR_BINTERVAL },
 
+	/* Blackmagic Design Intensity Shuttle */
+	{ USB_DEVICE(0x1edb, 0xbd3b), .driver_info = USB_QUIRK_NO_LPM },
+
+	/* Blackmagic Design UltraStudio SDI */
+	{ USB_DEVICE(0x1edb, 0xbd4f), .driver_info = USB_QUIRK_NO_LPM },
+
 	{ }  /* terminating entry must be last */
 };
 

@@ -47,4 +47,7 @@
 /* device generates spurious wakeup, ignore remote wakeup capability */
 #define USB_QUIRK_IGNORE_REMOTE_WAKEUP		BIT(9)
 
+/* device can't handle Link Power Management */
+#define USB_QUIRK_NO_LPM			BIT(10)
+
 #endif /* __LINUX_USB_QUIRKS_H */

Patches currently in stable-queue which might be from [email protected] are

queue-4.3/usb-storage-fix-scsi-sd-failure-invalid-field-in-cdb-for-usb-adapter-jmicron.patch queue-4.3/usb-host-ohci-at91-fix-a-crash-in-ohci_hcd_at91_overcurrent_irq.patch queue-4.3/usb-core-hub-fix-bos-null-pointer-kernel-panic.patch queue-4.3/usb-add-quirk-for-devices-with-broken-lpm.patch