Patch "USB: add quirk for devices with broken LPM" has been added to the 3.14-stable tree

Patch "USB: add quirk for devices with broken LPM" has been added to the 3.14-stable tree

[gregkh]

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 3.14-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-3.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From ad87e03213b552a5c33d5e1e7a19a73768397010 Mon Sep 17 00:00:00 2001
From: Alan Stern <stern@rowland.harvard.edu>
Date: Thu, 10 Dec 2015 15:27:21 -0500
Subject: USB: add quirk for devices with broken LPM

From: Alan Stern <stern@rowland.harvard.edu>

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.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-by: Steinar H. Gunderson <sgunderson@bigfoot.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 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(-)

--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -130,6 +130,10 @@ struct usb_hub *usb_hub_to_struct_hub(st
 
 static 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.
 	 */
@@ -4350,6 +4354,8 @@ 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) {
@@ -4595,7 +4601,6 @@ static void hub_port_connect_change(stru
 		if (status < 0)
 			goto loop;
 
-		usb_detect_quirks(udev);
 		if (udev->quirks & USB_QUIRK_DELAY_INIT)
 			msleep(1000);
 
--- a/drivers/usb/core/quirks.c
+++ b/drivers/usb/core/quirks.c
@@ -205,6 +205,12 @@ static const struct usb_device_id usb_am
 	/* Logitech Optical Mouse M90/M100 */
 	{ USB_DEVICE(0x046d, 0xc05a), .driver_info = USB_QUIRK_RESET_RESUME },
 
+	/* 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 */
 };
 
--- a/include/linux/usb/quirks.h
+++ b/include/linux/usb/quirks.h
@@ -36,4 +36,7 @@
 /* device can't handle device_qualifier descriptor requests */
 #define USB_QUIRK_DEVICE_QUALIFIER	0x00000100
 
+/* 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 stern@rowland.harvard.edu are

queue-3.14/usb-add-quirk-for-devices-with-broken-lpm.patch