linux-kernel - [PATCH][RFC] usb: hub: Cycle HUB power when initialization fails

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Message-Id: <1509707517-15669-1-git-send-email-mike.looijmans@topic.nl>
Date:   Fri,  3 Nov 2017 12:11:57 +0100
From:   Mike Looijmans <mike.looijmans@...ic.nl>
To:     linux-usb@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, gregkh@...uxfoundation.org,
        stern@...land.harvard.edu, linux@...ck-us.net,
        Mike Looijmans <mike.looijmans@...ic.nl>
Subject: [PATCH][RFC] usb: hub: Cycle HUB power when initialization fails

Sometimes the USB device gets confused about the state of the initialization and
the connection fails. In particular, the device thinks that it's already set up
and running while the host thinks the device still needs to be configured. To
work around this issue, power-cycle the hub's output to issue a sort of "reset"
to the device. This makes the device restart its state machine and then the
initialization succeeds.

This fixes problems where the kernel reports a list of errors like this:

usb 1-1.3: device not accepting address 19, error -71

The end result is a non-functioning device. After this patch, the sequence
becomes like this:

usb 1-1.3: new high-speed USB device number 18 using ci_hdrc
usb 1-1.3: device not accepting address 18, error -71
usb 1-1.3: new high-speed USB device number 19 using ci_hdrc
usb 1-1.3: device not accepting address 19, error -71
usb 1-1-port3: attempt power cycle
usb 1-1.3: new high-speed USB device number 21 using ci_hdrc
usb-storage 1-1.3:1.2: USB Mass Storage device detected

Signed-off-by: Mike Looijmans <mike.looijmans@...ic.nl>
---
This is a fix I did for a customer which might be appropriate for upstream. What do you think?

 drivers/usb/core/hub.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index e9ce6bb..a30c1e7 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -2611,7 +2611,7 @@ static unsigned hub_is_wusb(struct usb_hub *hub)
 #define PORT_RESET_TRIES	5
 #define SET_ADDRESS_TRIES	2
 #define GET_DESCRIPTOR_TRIES	2
-#define SET_CONFIG_TRIES	(2 * (use_both_schemes + 1))
+#define SET_CONFIG_TRIES	(4 * (use_both_schemes + 1))
 #define USE_NEW_SCHEME(i)	((i) / 2 == (int)old_scheme_first)
 
 #define HUB_ROOT_RESET_TIME	60	/* times are in msec */
@@ -4805,7 +4805,6 @@ static void hub_port_connect(struct usb_hub *hub, int port1, u16 portstatus,
 
 	status = 0;
 	for (i = 0; i < SET_CONFIG_TRIES; i++) {
-
 		/* reallocate for each attempt, since references
 		 * to the previous one can escape in various ways
 		 */
@@ -4935,6 +4934,15 @@ static void hub_port_connect(struct usb_hub *hub, int port1, u16 portstatus,
 		usb_put_dev(udev);
 		if ((status == -ENOTCONN) || (status == -ENOTSUPP))
 			break;
+
+		/* When halfway through our retry count, power-cycle the port */
+		if (i == (SET_CONFIG_TRIES / 2) - 1) {
+			dev_info(&port_dev->dev, "attempt power cycle\n");
+			usb_hub_set_port_power(hdev, hub, port1, false);
+			msleep(800);
+			usb_hub_set_port_power(hdev, hub, port1, true);
+			msleep(hub_power_on_good_delay(hub));
+		}
 	}
 	if (hub->hdev->parent ||
 			!hcd->driver->port_handed_over ||
@@ -5476,7 +5484,6 @@ static int usb_reset_and_verify_device(struct usb_device *udev)
 	udev->bos = NULL;
 
 	for (i = 0; i < SET_CONFIG_TRIES; ++i) {
-
 		/* ep0 maxpacket size may change; let the HCD know about it.
 		 * Other endpoints will be handled by re-enumeration. */
 		usb_ep0_reinit(udev);
-- 
1.9.1