[Qemu-devel] [PATCH 2/7] usb-host-libusb: Configuration 0 may be a valid configuration

[Gerd Hoffmann <kraxel@redhat.com>]

From: Hans de Goede <hdegoede@redhat.com>

Quoting from: linux/Documentation/ABI/stable/sysfs-bus-usb:

	Note that some devices, in violation of the USB spec, have a
	configuration with a value equal to 0. Writing 0 to
	bConfigurationValue for these devices will install that
	configuration, rather then unconfigure the device.

So don't compare the configuration value against 0 to check for unconfigured
devices, instead check for a LIBUSB_ERROR_NOT_FOUND return from
libusb_get_active_config_descriptor().

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 hw/usb/host-libusb.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/hw/usb/host-libusb.c b/hw/usb/host-libusb.c
index 428c7c5..35bae55 100644
--- a/hw/usb/host-libusb.c
+++ b/hw/usb/host-libusb.c
@@ -992,15 +992,14 @@ static int usb_host_claim_interfaces(USBHostDevice *s, int configuration)
     udev->ninterfaces   = 0;
     udev->configuration = 0;
 
-    if (configuration == 0) {
-        /* address state - ignore */
-        return USB_RET_SUCCESS;
-    }
-
     usb_host_detach_kernel(s);
 
     rc = libusb_get_active_config_descriptor(s->dev, &conf);
     if (rc != 0) {
+        if (rc == LIBUSB_ERROR_NOT_FOUND) {
+            /* address state - ignore */
+            return USB_RET_SUCCESS;
+        }
         return USB_RET_STALL;
     }
 
-- 
1.8.3.1