USB core: don't match interface descriptors for vendor-specific devices
This patch (as804) makes USB driver matching ignore the interface
class, subclass, and protocol if the device class is Vendor Specific.
Drivers can override this policy by specifying a Vendor ID as part
of the match; then vendor-specific matches are allowed.
Linus Walleij has reported a problem this patch fixes. When a
particular mass-storage device is switched from mass-storage mode to
Media Transfer Protocol, the interface class remains set to mass-storage
and usb-storage binds to it erroneously, even though the device class
changes to Vendor-Specific.
This may cause a problem for some drivers until their match records can
be updated to include Vendor IDs. But if it does, then those records
were broken to begin with.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
index 113e484..401d76f 100644
--- a/drivers/usb/core/driver.c
+++ b/drivers/usb/core/driver.c
@@ -408,6 +408,16 @@
(id->bDeviceProtocol != dev->descriptor.bDeviceProtocol))
return 0;
+ /* The interface class, subclass, and protocol should never be
+ * checked for a match if the device class is Vendor Specific,
+ * unless the match record specifies the Vendor ID. */
+ if (dev->descriptor.bDeviceClass == USB_CLASS_VENDOR_SPEC &&
+ !(id->match_flags & USB_DEVICE_ID_MATCH_VENDOR) &&
+ (id->match_flags & (USB_DEVICE_ID_MATCH_INT_CLASS |
+ USB_DEVICE_ID_MATCH_INT_SUBCLASS |
+ USB_DEVICE_ID_MATCH_INT_PROTOCOL)))
+ return 0;
+
if ((id->match_flags & USB_DEVICE_ID_MATCH_INT_CLASS) &&
(id->bInterfaceClass != intf->desc.bInterfaceClass))
return 0;
@@ -476,7 +486,17 @@
* most general; they let drivers bind to any interface on a
* multiple-function device. Use the USB_INTERFACE_INFO
* macro, or its siblings, to match class-per-interface style
- * devices (as recorded in bDeviceClass).
+ * devices (as recorded in bInterfaceClass).
+ *
+ * Note that an entry created by USB_INTERFACE_INFO won't match
+ * any interface if the device class is set to Vendor-Specific.
+ * This is deliberate; according to the USB spec the meanings of
+ * the interface class/subclass/protocol for these devices are also
+ * vendor-specific, and hence matching against a standard product
+ * class wouldn't work anyway. If you really want to use an
+ * interface-based match for such a device, create a match record
+ * that also specifies the vendor ID. (Unforunately there isn't a
+ * standard macro for creating records like this.)
*
* Within those groups, remember that not all combinations are
* meaningful. For example, don't give a product version range