[PATCH] USB: hub: add module parameters to usbcore for port init retries

[Ray Chi <raychi@google.com>]

Currently, there is a Kconfig (CONFIG_USB_FEW_INIT_RETRIES) to
reduce retries when the port initialization is failed. The retry
times are fixed and assigned in compile time. To improve the
flexibility, this patch add four module parameters:
port_reset_tries, set_address_tries, get_descriptor_tries,
and get_maxpacket0_tries, to replace the original default values.

The default value of module parameters is the same as before
to preserve the existing behavior.

Signed-off-by: Ray Chi <raychi@google.com>
---
 .../admin-guide/kernel-parameters.txt         | 16 ++++++++++
 drivers/usb/core/hub.c                        | 31 ++++++++++++++++---
 2 files changed, 42 insertions(+), 5 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 8090130b544b..c467b2778128 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -6277,6 +6277,22 @@
 			USB_REQ_GET_DESCRIPTOR request in milliseconds
 			(default 5000 = 5.0 seconds).
 
+	usbcore.port_reset_tries=
+			[USB] Set the retry time of port reset for each
+			port initialization (default PORT_RESET_TRIES = 5).
+
+	usbcore.set_address_tries=
+			[USB] set the retry time of set address for each
+			port initialization (default SET_ADDRESS_TRIES = 2).
+
+	usbcore.get_descriptor_tries=
+			[USB] set the retry time of set address for each
+			port initialization (default GET_DESCRIPTOR_TRIES = 2).
+
+	usbcore.get_maxpacket0_tries=
+			[USB] set the retry time of get maxpacket0 for each
+			port initialization (default GET_MAXPACKET0_TRIES = 3).
+
 	usbcore.nousb	[USB] Disable the USB subsystem
 
 	usbcore.quirks=
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index b7f66dcd1fe0..c5c695886424 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -2788,6 +2788,27 @@ static unsigned hub_is_wusb(struct usb_hub *hub)
 #define HUB_LONG_RESET_TIME	200
 #define HUB_RESET_TIMEOUT	800
 
+/* define retry time for port reset */
+static int port_reset_tries = PORT_RESET_TRIES;
+module_param(port_reset_tries, int, S_IRUGO|S_IWUSR);
+MODULE_PARM_DESC(port_reset_tries, "retry times of port reset for each port initialization");
+
+/* define retry time of set address */
+static int set_address_tries = SET_ADDRESS_TRIES;
+module_param(set_address_tries, int, S_IRUGO|S_IWUSR);
+MODULE_PARM_DESC(set_address_tries, "retry times of set address for each port initialization");
+
+/* define retry time of get descriptor */
+static int get_descriptor_tries = GET_DESCRIPTOR_TRIES;
+module_param(get_descriptor_tries, int, S_IRUGO|S_IWUSR);
+MODULE_PARM_DESC(get_descriptor_tries, "retry times of set address for each port initialization");
+
+/* define retry time of get maxpacket0 */
+static int get_maxpacket0_tries = GET_MAXPACKET0_TRIES;
+module_param(get_maxpacket0_tries, int, S_IRUGO|S_IWUSR);
+MODULE_PARM_DESC(get_maxpacket0_tries,
+		 "retry times of get maxpacket0 for each port initialization");
+
 static bool use_new_scheme(struct usb_device *udev, int retry,
 			   struct usb_port *port_dev)
 {
@@ -2965,7 +2986,7 @@ static int hub_port_reset(struct usb_hub *hub, int port1,
 	clear_bit(port1, hub->warm_reset_bits);
 
 	/* Reset the port */
-	for (i = 0; i < PORT_RESET_TRIES; i++) {
+	for (i = 0; i < port_reset_tries; i++) {
 		status = set_port_feature(hub->hdev, port1, (warm ?
 					USB_PORT_FEAT_BH_PORT_RESET :
 					USB_PORT_FEAT_RESET));
@@ -2989,7 +3010,7 @@ static int hub_port_reset(struct usb_hub *hub, int port1,
 		 * reset attempts to avoid warm reset loop.
 		 */
 		if (status == 0 || status == -ENOTCONN || status == -ENODEV ||
-		    (status == -EBUSY && i == PORT_RESET_TRIES - 1)) {
+		    (status == -EBUSY && i == port_reset_tries - 1)) {
 			usb_clear_port_feature(hub->hdev, port1,
 					USB_PORT_FEAT_C_RESET);
 
@@ -4788,7 +4809,7 @@ hub_port_init(struct usb_hub *hub, struct usb_device *udev, int port1,
 	 */
 	do_new_scheme = use_new_scheme(udev, retry_counter, port_dev);
 
-	for (retries = 0; retries < GET_DESCRIPTOR_TRIES; (++retries, msleep(100))) {
+	for (retries = 0; retries < get_descriptor_tries; (++retries, msleep(100))) {
 		if (do_new_scheme) {
 			struct usb_device_descriptor *buf;
 			int r = 0;
@@ -4812,7 +4833,7 @@ hub_port_init(struct usb_hub *hub, struct usb_device *udev, int port1,
 			 * 255 is for WUSB devices, we actually need to use
 			 * 512 (WUSB1.0[4.8.1]).
 			 */
-			for (operations = 0; operations < GET_MAXPACKET0_TRIES;
+			for (operations = 0; operations < get_maxpacket0_tries;
 					++operations) {
 				buf->bMaxPacketSize0 = 0;
 				r = usb_control_msg(udev, usb_rcvaddr0pipe(),
@@ -4873,7 +4894,7 @@ hub_port_init(struct usb_hub *hub, struct usb_device *udev, int port1,
 		 * authorization will assign the final address.
 		 */
 		if (udev->wusb == 0) {
-			for (operations = 0; operations < SET_ADDRESS_TRIES; ++operations) {
+			for (operations = 0; operations < set_address_tries; ++operations) {
 				retval = hub_set_address(udev, devnum);
 				if (retval >= 0)
 					break;
-- 
2.36.1.476.g0c4daa206d-goog