[PATCH] Bluetooth: btusb: CSR chip hangs when unbound

[Jose Ignacio Tornos Martinez <jtornosm@redhat.com>]

Bluetooth Dongles with CSR chip (i.e. USB Bluetooth V4.0 Dongle by
Trust) hang when they are unbound from 'unbind' sysfs entry and
can not be bound again.

The reason is CSR chip hangs when usb configuration command with
index 0 (used to unconfigure) is sent during disconnection.

To avoid this unwanted result, it is necessary not to send this
command for CSR chip when usb device is unbound, so a new quirk
has been created for this device.

Athough device is not unconfigured, it is better to avoid device
hanging to be able to operate. Even bluetooth can be previously
turned off.
On the other hand, this is not important if usb device is going to
be bound again (normal behavior), i.e. with usbip.
---
 drivers/usb/core/generic.c | 3 ++-
 drivers/usb/core/quirks.c  | 3 +++
 include/linux/usb/quirks.h | 3 +++
 3 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/core/generic.c b/drivers/usb/core/generic.c
index 740342a2812a..ea770b83d876 100644
--- a/drivers/usb/core/generic.c
+++ b/drivers/usb/core/generic.c
@@ -22,6 +22,7 @@
 #include <linux/usb.h>
 #include <linux/usb/hcd.h>
 #include <uapi/linux/usb/audio.h>
+#include <linux/usb/quirks.h>
 #include "usb.h"
 
 static inline const char *plural(int n)
@@ -256,7 +257,7 @@ void usb_generic_driver_disconnect(struct usb_device *udev)
 
 	/* if this is only an unbind, not a physical disconnect, then
 	 * unconfigure the device */
-	if (udev->actconfig)
+	if (!(udev->quirks & USB_QUIRK_SKIP_UNCONFIGURE) && udev->actconfig)
 		usb_set_configuration(udev, -1);
 }
 
diff --git a/drivers/usb/core/quirks.c b/drivers/usb/core/quirks.c
index d3c14b5ed4a1..13989629d743 100644
--- a/drivers/usb/core/quirks.c
+++ b/drivers/usb/core/quirks.c
@@ -510,6 +510,9 @@ static const struct usb_device_id usb_quirk_list[] = {
 	/* INTEL VALUE SSD */
 	{ USB_DEVICE(0x8086, 0xf1a5), .driver_info = USB_QUIRK_RESET_RESUME },
 
+	/* CSR Bluetooth */
+	{ USB_DEVICE(0x0a12, 0x0001), .driver_info = USB_QUIRK_SKIP_UNCONFIGURE },
+
 	{ }  /* terminating entry must be last */
 };
 
diff --git a/include/linux/usb/quirks.h b/include/linux/usb/quirks.h
index eeb7c2157c72..84ab0a369931 100644
--- a/include/linux/usb/quirks.h
+++ b/include/linux/usb/quirks.h
@@ -72,4 +72,7 @@
 /* device has endpoints that should be ignored */
 #define USB_QUIRK_ENDPOINT_IGNORE		BIT(15)
 
+/* device doesn't support unconfigure when unbound. */
+#define USB_QUIRK_SKIP_UNCONFIGURE		BIT(16)
+
 #endif /* __LINUX_USB_QUIRKS_H */
-- 
2.35.1