illumos gate

The USB devices on test are:

> ::prtusb
INDEX   DRIVER      INST  NODE          GEN  VID.PID     PRODUCT     
1       xhci        0     pci15d9,1b58  3.0  0000.0000   No Product String
2       hubd        0     hub           2.0  1d6b.0107   USB Virtual Hub
3       scsa2usb    0     storage       2.0  05e3.0715   SD Card Reader
4       scsa2usb    1     storage       3.0  152d.0579   External USB 3.0
5       usb_mid     0     device        2.0  0557.9241   SMCI HID KM
6       usb_mid     1     miscellaneous 2.0  0b1f.03ee   RNDIS/Ethernet Gadget

know for xhci

> ::xhci_device
Aspeed - USB Virtual Hub
Port 01 | Slot 01 | # Endpoints 02
EP   Type       State      Head   Tail  
0    CONTROL    Running    0x8c   0x8c  
2    INTR IN    Running    0x23   0x1b  

Hama - SD Card Reader
Port 11 | Slot 02 | # Endpoints 03
EP   Type       State      Head   Tail  
0    CONTROL    Running    0x2a   0x2a  
2    BULK IN    Running    0x8c   0x8c  
3    BULK OUT   Running    0xa7   0xa7  

Intenso - External USB 3.0
Port 18 | Slot 03 | # Endpoints 03
EP   Type       State      Head   Tail  
0    CONTROL    Running    0x32   0x32  
2    BULK IN    Running    0xfd   0xfd  
3    BULK OUT   Running    0xec   0xec  

Linux 5.4.62 with aspeed_vhub - SMCI HID KM
Port 01 | Slot 04 | # Endpoints 03
EP   Type       State      Head   Tail  
0    CONTROL    Stopped    0x44   0x44  
2    INTR IN    Running    0x8    0x0   
4    INTR IN    Running    0x8    0x0   

Linux 5.4.62 with aspeed_vhub - RNDIS/Ethernet Gadget
Port 02 | Slot 05 | # Endpoints 01
EP   Type       State      Head   Tail  
0    CONTROL    Running    0x1d   0x1d  

At the moment of disconnecting the boot device ::usba_debug_buf reports (hubdi.c:3947)

hubd_hotplug_thread: port 18 mask=0x40000 change=0x7fc0000 connected=0x1

0x40000 stands for port 18, 0x7fc0000 reports a change on port 18

then

hubd_determine_port_status: port=18, state=0x103 ack=0xff
hubd_determine_port_status: port 18 read status=0x1103, change=0x0

then (hubdi.c:3966)

handle port 18:
new status=0x1103 change=0x0 was_conn=0x1

no change, status 0x1103.

So the new status has the change in 0x1000. For USB 2.0 we have defined

#define PORT_STATUS_PIC         0x1000  /* port indicator control */

for USB3.0 we have a bit maks

#define PORT_STATUS_SPMASK_SS   0x1c00

Corresponding the USB3 specification, the bits 10-12 represents the negotiated speed. Unfortunately the spec in table 10.16.2.6.1 is here not helpfull: mentions only reserved ???

Can we mask out the change of the speed bits and so get rid of the disconnect problem?

I would revoke my first attempt (2731) and suggest the following change to prevent the disconnect the bootdevice:

diff --git a/usr/src/uts/common/io/usb/usba/hubdi.c b/usr/src/uts/common/io/usb/usba/hubdi.c
index 5207a51490..7cc90ccb8a 100644
--- a/usr/src/uts/common/io/usb/usba/hubdi.c
+++ b/usr/src/uts/common/io/usb/usba/hubdi.c
@@ -3938,6 +3938,7 @@ hubd_hotplug_thread(void *arg)
                for (port = 1; port <= nports; port++) {
                        usb_port_mask_t port_mask;
                        boolean_t was_connected;
+                 uint16_t prevstate = hubd->h_port_state[port];

                        port_mask = 1 << port;
                        was_connected =
@@ -3992,7 +3993,17 @@ hubd_hotplug_thread(void *arg)
                         * Now check what changed on the port
                         */
                        if ((change & PORT_CHANGE_CSC) || attach_flg) {
-                           if ((status & PORT_STATUS_CCS) &&
+                         if (attach_flg && change == 0 &&
+                             hubd->h_usba_device->usb_port_status >= USBA_SUPER_SPEED_DEV &&
+                             (status & ~PORT_STATUS_SPMASK_SS) == prevstate)
+                         {
+                                 cmn_err(CE_WARN,
+                                     "port=%d status=%x ignore change - " 
+                                     "status=0x%x, change=0x%x",
+                                     port,
+                                     hubd->h_usba_device->usb_port_status,
+                                     status, change);
+                         } else if ((status & PORT_STATUS_CCS) &&
                                    (!was_connected)) {
                                        /* new device plugged in */
                                        online_child |=

This change prevents the disconnect of the boot device on usba driver attach, if the detected port status change is related only to the USB3 speed bits.