From 53ba5936b5c70b030d81e8f2349d75a7264581ae Mon Sep 17 00:00:00 2001
From: Michael Brown <mcb30@ipxe.org>
Date: Mon, 7 Dec 2015 00:54:01 +0000
Subject: [PATCH] [usb] Allow additional settling time for out-of-spec hubs

Some hubs (e.g. the Avocent Corp. Virtual Hub on a Lenovo x3550
Integrated Management Module) have been observed to require more than
the standard 200ms for ports to stabilise, with the result that
devices appear to disconnect and immediately reconnect during the
initial bus enumeration.

Work around this problem by allowing specific hubs an extra 500ms of
settling time.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
---
 src/drivers/usb/usbhub.c | 11 +++++++++++
 src/drivers/usb/usbhub.h |  8 ++++++++
 2 files changed, 19 insertions(+)

diff --git a/src/drivers/usb/usbhub.c b/src/drivers/usb/usbhub.c
index a3e7bc00c..7095fc31b 100644
--- a/src/drivers/usb/usbhub.c
+++ b/src/drivers/usb/usbhub.c
@@ -155,6 +155,10 @@ static int hub_open ( struct usb_hub *hub ) {
 	/* Refill interrupt ring */
 	hub_refill ( hubdev );
 
+	/* Delay to allow ports to stabilise on out-of-spec hubs */
+	if ( hubdev->flags & USB_HUB_SLOW_START )
+		mdelay ( USB_HUB_SLOW_START_DELAY_MS );
+
 	return 0;
 
 	usb_endpoint_close ( &hubdev->intr );
@@ -410,6 +414,7 @@ static int hub_probe ( struct usb_function *func,
 	hubdev->usb = usb;
 	hubdev->features =
 		( enhanced ? USB_HUB_FEATURES_ENHANCED : USB_HUB_FEATURES );
+	hubdev->flags = func->id->driver_data;
 	usb_endpoint_init ( &hubdev->intr, usb, &usb_hub_intr_operations );
 	usb_refill_init ( &hubdev->intr, 0, USB_HUB_INTR_FILL );
 	process_init_stopped ( &hubdev->refill, &hub_refill_desc, NULL );
@@ -517,6 +522,12 @@ static void hub_remove ( struct usb_function *func ) {
 
 /** USB hub device IDs */
 static struct usb_device_id hub_ids[] = {
+	{
+		.name = "avocent-hub",
+		.vendor = 0x0624,
+		.product = 0x0248,
+		.driver_data = USB_HUB_SLOW_START,
+	},
 	{
 		.name = "hub",
 		.vendor = USB_ANY_ID,
diff --git a/src/drivers/usb/usbhub.h b/src/drivers/usb/usbhub.h
index d7d8f9610..a5f123acc 100644
--- a/src/drivers/usb/usbhub.h
+++ b/src/drivers/usb/usbhub.h
@@ -257,6 +257,8 @@ struct usb_hub_device {
 	struct usb_hub *hub;
 	/** Features */
 	unsigned int features;
+	/** Flags */
+	unsigned int flags;
 
 	/** Interrupt endpoint */
 	struct usb_endpoint intr;
@@ -264,6 +266,12 @@ struct usb_hub_device {
 	struct process refill;
 };
 
+/** Hub requires additional settling delay */
+#define USB_HUB_SLOW_START 0x0001
+
+/** Additional setting delay for out-of-spec hubs */
+#define USB_HUB_SLOW_START_DELAY_MS 500
+
 /** Interrupt ring fill level
  *
  * This is a policy decision.