This patch removes code from usb_choose_configuration()
responsible for ignoring the first USB device configuration if
its first interface is RNDIS. Instead,
usb_choose_configuration() chooses configuration with lowest
bConfigurationValue. Linux' Ethernet gadget uses a lower
bConfigurationValue for the second configuration which is
a CDC configuration so this code should choose configuration
that suits Linux better.
Signed-off-by: Michal Nazarewicz <m.nazarewicz@xxxxxxxxxxx>
---
Just what I had in mind if anyone interested... Not that I have any
strong opinion about it. Also, not tested.
drivers/usb/core/generic.c | 47 +++++++++++++++++++++----------------------
1 files changed, 23 insertions(+), 24 deletions(-)
diff --git a/drivers/usb/core/generic.c b/drivers/usb/core/generic.c
index 9a34ccb..5b411af 100644
--- a/drivers/usb/core/generic.c
+++ b/drivers/usb/core/generic.c
@@ -46,6 +46,7 @@ int usb_choose_configuration(struct usb_device *udev)
int num_configs;
int insufficient_power = 0;
struct usb_host_config *c, *best;
+ int best_is_not_class = 1;
best = NULL;
c = udev->config;
@@ -102,33 +103,31 @@ int usb_choose_configuration(struct usb_device *udev)
continue;
}
- /* When the first config's first interface is one of Microsoft's
- * pet nonstandard Ethernet-over-USB protocols, ignore it unless
- * this kernel has enabled the necessary host side driver.
- */
- if (i == 0 && desc && (is_rndis(desc) || is_activesync(desc))) {
-#if !defined(CONFIG_USB_NET_RNDIS_HOST) && !defined(CONFIG_USB_NET_RNDIS_HOST_MODULE)
+ /* From the remaining configs, choose one whose first
+ * interface is for a non-vendor-specific class and
+ * has lowest bConfigurationValue. Reason for the
+ * former: Linux is more likely to have a class driver
+ * than a vendor-specific driver. Reason for the
+ * latter: Ethernet gadget use lower
+ * bConfigurationValue for configuration with CDC ECM
+ * which is preferred by Linux even though it's second
+ * configuration. */
+ if (udev->descriptor.bDeviceClass !=
+ USB_CLASS_VENDOR_SPEC &&
+ (desc && desc->bInterfaceClass !=
+ USB_CLASS_VENDOR_SPEC)) {
+ if (best_is_not_class ||
+ c->desc.bConfigurationValue <
+ best->desc.bConfigurationValue) {
+ best_is_not_class = 0;
+ best = c;
+ }
continue;
-#else
- best = c;
-#endif
- }
-
- /* From the remaining configs, choose the first one whose
- * first interface is for a non-vendor-specific class.
- * Reason: Linux is more likely to have a class driver
- * than a vendor-specific driver. */
- else if (udev->descriptor.bDeviceClass !=
- USB_CLASS_VENDOR_SPEC &&
- (desc && desc->bInterfaceClass !=
- USB_CLASS_VENDOR_SPEC)) {
- best = c;
- break;
}
/* If all the remaining configs are vendor-specific,
* choose the first one. */
- else if (!best)
+ if (!best)
best = c;
}
--
1.7.1
--
To unsubscribe from this list: send the line "unsubscribe linux-usb" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
