usb: misc: ehset: Workaround for "special" hubs

The USB2.0 spec chapter 11.24.2.13 says that the USB port which is going
under test needs to be put in suspend state before sending the test
command. Many hubs, don't enforce this precondition and they work fine
without this step. But there are some "special" hubs, which requires to
disable the port power before sending the test command.

Because the USB spec mention that the port should be suspended, also
do this step before sending the test command. This could rise the
problem with other hubs which are not compliant with the spec and the
test command will not work if the port is suspend. If such hubs are
found, a similar workaround like the disable part could be implemented
to skip the suspend port command.
Signed-off-by: Razvan Heghedus <heghedus.razvan@gmail.com>
Link: https://lore.kernel.org/r/20210915121615.3790-1-heghedus.razvan@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/misc/ehset.c

@@ -18,6 +18,47 @@
 #define TEST_SINGLE_STEP_GET_DEV_DESC		0x0107
 #define TEST_SINGLE_STEP_SET_FEATURE		0x0108
 
+/*
+ * A list of USB hubs which requires to disable the power
+ * to the port before starting the testing procedures.
+ */
+static const struct usb_device_id ehset_hub_list[] = {
+	{USB_DEVICE(0x0424, 0x4502)},
+	{USB_DEVICE(0x0424, 0x4913)},
+	{USB_DEVICE(0x0451, 0x8027)},
+	{}
+};
+
+static int ehset_prepare_port_for_testing(struct usb_device *hub_udev, u16 portnum)
+{
+	int ret = 0;
+
+	/*
+	 * The USB2.0 spec chapter 11.24.2.13 says that the USB port which is
+	 * going under test needs to be put in suspend before sending the
+	 * test command. Most hubs don't enforce this precondition, but there
+	 * are some hubs which needs to disable the power to the port before
+	 * starting the test.
+	 */
+	if (usb_match_id(to_usb_interface(hub_udev->dev.parent), ehset_hub_list)) {
+		ret = usb_control_msg_send(hub_udev, 0, USB_REQ_CLEAR_FEATURE,
+					   USB_RT_PORT, USB_PORT_FEAT_ENABLE,
+					   portnum, NULL, 0, 1000, GFP_KERNEL);
+		/* Wait for the port to be disabled. It's an arbitrary value
+		 * which worked every time.
+		 */
+		msleep(100);
+	} else {
+		/* For the hubs which are compliant with the spec,
+		 * put the port in SUSPEND.
+		 */
+		ret = usb_control_msg_send(hub_udev, 0, USB_REQ_SET_FEATURE,
+					   USB_RT_PORT, USB_PORT_FEAT_SUSPEND,
+					   portnum, NULL, 0, 1000, GFP_KERNEL);
+	}
+	return ret;
+}
+
 static int ehset_probe(struct usb_interface *intf,
 		       const struct usb_device_id *id)
 {
@@ -30,24 +71,32 @@ static int ehset_probe(struct usb_interface *intf,
 
 	switch (test_pid) {
 	case TEST_SE0_NAK_PID:
+		ret = ehset_prepare_port_for_testing(hub_udev, portnum);
+		if (!ret)
 			ret = usb_control_msg_send(hub_udev, 0, USB_REQ_SET_FEATURE,
 						   USB_RT_PORT, USB_PORT_FEAT_TEST,
 						   (USB_TEST_SE0_NAK << 8) | portnum,
 						   NULL, 0, 1000, GFP_KERNEL);
 		break;
 	case TEST_J_PID:
+		ret = ehset_prepare_port_for_testing(hub_udev, portnum);
+		if (!ret)
 			ret = usb_control_msg_send(hub_udev, 0, USB_REQ_SET_FEATURE,
 						   USB_RT_PORT, USB_PORT_FEAT_TEST,
 						   (USB_TEST_J << 8) | portnum, NULL, 0,
 						   1000, GFP_KERNEL);
 		break;
 	case TEST_K_PID:
+		ret = ehset_prepare_port_for_testing(hub_udev, portnum);
+		if (!ret)
 			ret = usb_control_msg_send(hub_udev, 0, USB_REQ_SET_FEATURE,
 						   USB_RT_PORT, USB_PORT_FEAT_TEST,
 						   (USB_TEST_K << 8) | portnum, NULL, 0,
 						   1000, GFP_KERNEL);
 		break;
 	case TEST_PACKET_PID:
+		ret = ehset_prepare_port_for_testing(hub_udev, portnum);
+		if (!ret)
 			ret = usb_control_msg_send(hub_udev, 0, USB_REQ_SET_FEATURE,
 						   USB_RT_PORT, USB_PORT_FEAT_TEST,
 						   (USB_TEST_PACKET << 8) | portnum,