[PATCH v2] usb: core: Avoid doing warm reset on disconnect event
From: Kai-Heng Feng
Date: Fri Nov 26 2021 - 06:59:47 EST
Unplugging USB device may cause an incorrect warm reset loop:
[ 143.039019] xhci_hcd 0000:00:14.0: Port change event, 2-3, id 19, portsc: 0x4202c0
[ 143.039025] xhci_hcd 0000:00:14.0: handle_port_status: starting usb2 port polling.
[ 143.039051] hub 2-0:1.0: state 7 ports 10 chg 0000 evt 0008
[ 143.039058] xhci_hcd 0000:00:14.0: Get port status 2-3 read: 0x4202c0, return 0x4102c0
[ 143.039092] xhci_hcd 0000:00:14.0: clear port3 connect change, portsc: 0x4002c0
[ 143.039096] usb usb2-port3: link state change
[ 143.039099] xhci_hcd 0000:00:14.0: clear port3 link state change, portsc: 0x2c0
[ 143.039101] usb usb2-port3: do warm reset
[ 143.096736] xhci_hcd 0000:00:14.0: Get port status 2-3 read: 0x2b0, return 0x2b0
[ 143.096751] usb usb2-port3: not warm reset yet, waiting 50ms
[ 143.131500] xhci_hcd 0000:00:14.0: Can't queue urb, port error, link inactive
[ 143.138260] xhci_hcd 0000:00:14.0: Port change event, 2-3, id 19, portsc: 0x2802a0
[ 143.138263] xhci_hcd 0000:00:14.0: handle_port_status: starting usb2 port polling.
[ 143.160756] xhci_hcd 0000:00:14.0: Get port status 2-3 read: 0x2802a0, return 0x3002a0
[ 143.160798] usb usb2-port3: not warm reset yet, waiting 200ms
The warm reset is due to its PLS is in eSS.Inactive state. However, USB
3.2 spec table 10-13 mentions "Ports can be disabled by either a fault
condition (disconnect event or other fault condition)", xHCI 1.2 spec
table 5-27 also states that "This flag shall automatically be cleared to
‘0’ by a disconnect event or other fault condition." on PED.
So use CSC = 0 and PED = 0 as indication that device is disconnecting to
avoid doing warm reset.
Signed-off-by: Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx>
---
v2:
- Change the variable type to bool.
drivers/usb/core/hub.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index a9a04ea967019..4f081df70ecf2 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -5564,6 +5564,7 @@ static void port_event(struct usb_hub *hub, int port1)
__must_hold(&port_dev->status_lock)
{
int connect_change;
+ bool disconnect = false;
struct usb_port *port_dev = hub->ports[port1 - 1];
struct usb_device *udev = port_dev->child;
struct usb_device *hdev = hub->hdev;
@@ -5579,6 +5580,9 @@ static void port_event(struct usb_hub *hub, int port1)
if (portchange & USB_PORT_STAT_C_CONNECTION) {
usb_clear_port_feature(hdev, port1, USB_PORT_FEAT_C_CONNECTION);
connect_change = 1;
+ if (!(portstatus & USB_PORT_STAT_CONNECTION) &&
+ !(portstatus & USB_PORT_STAT_ENABLE))
+ disconnect = true;
}
if (portchange & USB_PORT_STAT_C_ENABLE) {
@@ -5647,7 +5651,7 @@ static void port_event(struct usb_hub *hub, int port1)
* Warm reset a USB3 protocol port if it's in
* SS.Inactive state.
*/
- if (hub_port_warm_reset_required(hub, port1, portstatus)) {
+ if (hub_port_warm_reset_required(hub, port1, portstatus) && !disconnect) {
dev_dbg(&port_dev->dev, "do warm reset\n");
if (!udev || !(portstatus & USB_PORT_STAT_CONNECTION)
|| udev->state == USB_STATE_NOTATTACHED) {
--
2.32.0