[PATCH v4] USB: core: skip unconfiguration if device doesn't support it

[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, so a new quirk has been created.

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.

Signed-off-by: Jose Ignacio Tornos Martinez <jtornosm@redhat.com>
---
V3 -> V4:
- Reorder quirk entries to be in numerical order according to the vendor
ID and product ID.
- Add patch version information.
V2 -> V3:
- Change subject (Bluetooth: btusb: CSR chip hangs when unbound ->
USB: core: skip unconfiguration if device doesn't support it).
- Improve quirk checking.
- Allow to test quirk interactively.
V1 -> V2:
- Use quirk feature for the exception.

 Documentation/admin-guide/kernel-parameters.txt |  2 ++
 drivers/usb/core/message.c                      | 12 +++++++++---
 drivers/usb/core/quirks.c                       |  6 ++++++
 include/linux/usb/quirks.h                      |  3 +++
 4 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 3f1cc5e317ed..71651b888d14 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -6183,6 +6183,8 @@
 					pause after every control message);
 				o = USB_QUIRK_HUB_SLOW_RESET (Hub needs extra
 					delay after resetting its port);
+				p = USB_QUIRK_SKIP_UNCONFIGURE (device doesn't
+					support unconfigure);
 			Example: quirks=0781:5580:bk,0a5c:5834:gij
 
 	usbhid.mousepoll=
diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c
index 4d59d927ae3e..9c6cd0c75f4f 100644
--- a/drivers/usb/core/message.c
+++ b/drivers/usb/core/message.c
@@ -2108,9 +2108,15 @@ int usb_set_configuration(struct usb_device *dev, int configuration)
 	}
 	kfree(new_interfaces);
 
-	ret = usb_control_msg_send(dev, 0, USB_REQ_SET_CONFIGURATION, 0,
-				   configuration, 0, NULL, 0,
-				   USB_CTRL_SET_TIMEOUT, GFP_NOIO);
+	if (configuration == 0 && !cp
+			&& (dev->quirks & USB_QUIRK_SKIP_UNCONFIGURE)) {
+		dev_warn(&dev->dev, "device is not unconfigured!\n");
+		ret = 0;
+	} else
+		ret = usb_control_msg_send(dev, 0, USB_REQ_SET_CONFIGURATION, 0,
+					   configuration, 0, NULL, 0,
+					   USB_CTRL_SET_TIMEOUT, GFP_NOIO);
+
 	if (ret && cp) {
 		/*
 		 * All the old state is gone, so what else can we do?
diff --git a/drivers/usb/core/quirks.c b/drivers/usb/core/quirks.c
index d3c14b5ed4a1..7c86c8d61570 100644
--- a/drivers/usb/core/quirks.c
+++ b/drivers/usb/core/quirks.c
@@ -138,6 +138,9 @@ static int quirks_param_set(const char *value, const struct kernel_param *kp)
 			case 'o':
 				flags |= USB_QUIRK_HUB_SLOW_RESET;
 				break;
+			case 'p':
+				flags |= USB_QUIRK_SKIP_UNCONFIGURE;
+				break;
 			/* Ignore unrecognized flag characters */
 			}
 		}
@@ -394,6 +397,9 @@ static const struct usb_device_id usb_quirk_list[] = {
 	/* ELMO L-12F document camera */
 	{ USB_DEVICE(0x09a1, 0x0028), .driver_info = USB_QUIRK_DELAY_CTRL_MSG },
 
+	/* CSR Bluetooth */
+	{ USB_DEVICE(0x0a12, 0x0001), .driver_info = USB_QUIRK_SKIP_UNCONFIGURE },
+
 	/* Broadcom BCM92035DGROM BT dongle */
 	{ USB_DEVICE(0x0a5c, 0x2021), .driver_info = USB_QUIRK_RESET_RESUME },
 
diff --git a/include/linux/usb/quirks.h b/include/linux/usb/quirks.h
index eeb7c2157c72..79cb0616f394 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. */
+#define USB_QUIRK_SKIP_UNCONFIGURE		BIT(16)
+
 #endif /* __LINUX_USB_QUIRKS_H */
-- 
2.35.1