[PATCH 5/6] usb: skip endpoint descriptors for endpoint zero

[Ana Bobillo <anabobillo3@gmail.com>]

From: Ana Bobillo <anabobillo3@gmail.com>

Endpoint zero is the default control endpoint, which every device has
and no interface describes. usb_parse_config() still stores an endpoint
descriptor numbered zero like any other, so it reaches the users of
ep_desc[]: usb_set_maxpacket() overwrites endpoint zero's packet sizes
with it, and on xHCI, xhci_get_ep_index() gives an OUT endpoint zero
the index -1, which xhci_init_ep_contexts_if() then uses for the
device's endpoint contexts and rings.

Skip such a descriptor, and the companion descriptor after it, as Linux
does in usb_parse_endpoint(). Add a test with a device that has one,
which also checks that endpoint zero keeps its packet size.

Signed-off-by: Ana Bobillo <anabobillo3@gmail.com>
---
 common/usb.c  |  7 +++++++
 test/dm/usb.c | 36 ++++++++++++++++++++++++++++++++++++
 2 files changed, 43 insertions(+)

diff --git a/common/usb.c b/common/usb.c
index 05502da6b30..619132512dd 100644
--- a/common/usb.c
+++ b/common/usb.c
@@ -466,6 +466,13 @@ static int usb_parse_config(struct usb_device *dev,
 				break;
 			}
 			if_desc = &dev->config.if_desc[ifno];
+			/* endpoint zero is the default control endpoint */
+			if (usb_endpoint_num((struct usb_endpoint_descriptor *)
+					     head) == 0) {
+				printf("Interface %d has a descriptor for endpoint zero, skipping\n",
+				       if_desc->desc.bInterfaceNumber);
+				break;
+			}
 			if (if_desc->no_of_ep >= USB_MAXENDPOINTS) {
 				printf("Interface %d has too many endpoints!\n",
 					if_desc->desc.bInterfaceNumber);
diff --git a/test/dm/usb.c b/test/dm/usb.c
index 145ce79dfec..4975a952d87 100644
--- a/test/dm/usb.c
+++ b/test/dm/usb.c
@@ -574,6 +574,42 @@ static int scan_port1(struct unit_test_state *uts, void **desc_list,
 	return 0;
 }
 
+/* test that a descriptor for endpoint zero is ignored */
+static int dm_test_usb_config_ep0(struct unit_test_state *uts)
+{
+	static struct usb_interface_descriptor interface0;
+	static struct usb_endpoint_descriptor endpoint0 = {
+		.bLength		= USB_DT_ENDPOINT_SIZE,
+		.bDescriptorType	= USB_DT_ENDPOINT,
+		.bEndpointAddress	= 0,
+		.bmAttributes		= USB_ENDPOINT_XFER_BULK,
+		.wMaxPacketSize		= cpu_to_le16(512),
+	};
+	static void *desc_list[] = {
+		&vendor_device_desc,
+		&vendor_config0,
+		&interface0,
+		&endpoint0,
+		&vendor_endpoint1_in,
+		NULL,
+	};
+	struct usb_device *udev;
+
+	interface0 = vendor_interface0;
+	interface0.bNumEndpoints = 2;
+	ut_assertok(scan_port1(uts, desc_list, &udev));
+	ut_assertnonnull(udev);
+	ut_asserteq(1, udev->config.if_desc[0].no_of_ep);
+	ut_asserteq(1 | USB_DIR_IN,
+		    udev->config.if_desc[0].ep_desc[0].bEndpointAddress);
+	ut_asserteq(64, udev->epmaxpacketin[0]);
+	ut_asserteq(64, udev->epmaxpacketout[0]);
+	ut_assertok(usb_stop());
+
+	return 0;
+}
+DM_TEST(dm_test_usb_config_ep0, UTF_SCAN_PDATA | UTF_SCAN_FDT);
+
 /* test that interface and endpoint counts are limited to those described */
 static int dm_test_usb_config_counts(struct unit_test_state *uts)
 {