On Tue, Nov 30, 2021 at 10:36 AM Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx> wrote: > > On Mon, Nov 29, 2021 at 6:18 PM Mathias Nyman > <mathias.nyman@xxxxxxxxxxxxxxx> wrote: > > > > On 26.11.2021 13.56, Kai-Heng Feng wrote: > > > 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. > > > > My understanding is that PED = 0 in case of disconnect, error (PLS=Inactive), or > > during active reset signalling. See xHCI Figure 4-27: USB3 Root Hub Port State Machine. > > signal states (0,0,0,0) are PP,CCS,PED,PR. > > I think it's 1,0,0,0? So for my case, the port is in Error state (PLS > = Inactive, 1,0,0,0). > > > > > I'm looking at a similar case where Inactive link is reported at disconnect for a while > > before missing terminations are detected and link finally goes to RxDetect. > > So the PLS goes from Inactive to RxDetect after a while? > Is the case you are working on also EHL? > > > > > If the port was reset immediately when Inactive link state was reported the port stays stuck > > in port reset. > > This might have been related to the address0 locking issues recently fixed. > > > > Anyway, to avoid the extra reset of a removed USB3 device I started polling the link state of > > the Inactive link for some time before resetting it. This gives the link time to detect > > missing terminations and go to RxDetect, and driver can skip the reset. > > > > Planning on upstreaming it, patch is here: > > https://git.kernel.org/pub/scm/linux/kernel/git/mnyman/xhci.git/commit/?h=fix_avoid_disconnect_reset&id=72d20c026b7812d096c6b5184a3888894401c829 > > Thanks, let me test this out. The result is negative, here's the relevant log: [ 128.219129] xhci_hcd 0000:00:14.0: Port change event, 2-2, id 18, portsc: 0x4202c0 [ 128.219143] xhci_hcd 0000:00:14.0: handle_port_status: starting port polling. [ 128.219201] hub 2-0:1.0: state 7 ports 10 chg 0000 evt 0004 [ 128.219217] xhci_hcd 0000:00:14.0: Get port status 2-2 read: 0x4202c0, return 0x4102c0 [ 128.219244] xhci_hcd 0000:00:14.0: clear port2 connect change, portsc: 0x4002c0 [ 128.219256] usb usb2-port2: link state change [ 128.219264] xhci_hcd 0000:00:14.0: clear port2 link state change, portsc: 0x2c0 [ 128.232326] xhci_hcd 0000:00:14.0: xhci_hub_status_data: stopping port polling. [ 128.244356] xhci_hcd 0000:00:14.0: Get port status 2-2 read: 0x2c0, return 0x2c0 [ 128.244383] usb usb2-port2: Wait for inactive link disconnect detect [ 128.272342] xhci_hcd 0000:00:14.0: Get port status 2-2 read: 0x2c0, return 0x2c0 [ 128.272370] usb usb2-port2: Wait for inactive link disconnect detect [ 128.300348] xhci_hcd 0000:00:14.0: Get port status 2-2 read: 0x2c0, return 0x2c0 [ 128.300375] usb usb2-port2: Wait for inactive link disconnect detect [ 128.328342] xhci_hcd 0000:00:14.0: Get port status 2-2 read: 0x2c0, return 0x2c0 [ 128.328369] usb usb2-port2: Wait for inactive link disconnect detect [ 128.356343] xhci_hcd 0000:00:14.0: Get port status 2-2 read: 0x2c0, return 0x2c0 [ 128.356370] usb usb2-port2: Wait for inactive link disconnect detect [ 128.356374] usb usb2-port2: do warm reset, port only [ 128.377500] xhci_hcd 0000:00:14.0: Port change event, 1-2, id 2, portsc: 0x206e1 [ 128.377515] xhci_hcd 0000:00:14.0: handle_port_status: starting port polling. [ 128.377570] hub 1-0:1.0: state 7 ports 16 chg 0000 evt 0004 [ 128.377586] xhci_hcd 0000:00:14.0: Get port status 1-2 read: 0x206e1, return 0x10101 [ 128.377614] xhci_hcd 0000:00:14.0: clear port2 connect change, portsc: 0x6e1 [ 128.377626] usb usb1-port2: status 0101, change 0001, 12 Mb/s [ 128.377636] xhci_hcd 0000:00:14.0: Get port status 1-2 read: 0x6e1, return 0x101 [ 128.398304] xhci_hcd 0000:00:14.0: Port change event, 1-2, id 2, portsc: 0x202a0 [ 128.398319] xhci_hcd 0000:00:14.0: handle_port_status: starting port polling. [ 128.412343] xhci_hcd 0000:00:14.0: Get port status 1-2 read: 0x202a0, return 0x10100 [ 128.412376] xhci_hcd 0000:00:14.0: clear port2 connect change, portsc: 0x2a0 [ 128.416337] xhci_hcd 0000:00:14.0: Get port status 2-2 read: 0x2b0, return 0x2b0 [ 128.416368] usb usb2-port2: not warm reset yet, waiting 50ms [ 128.448341] xhci_hcd 0000:00:14.0: Get port status 1-2 read: 0x2a0, return 0x100 [ 128.476335] xhci_hcd 0000:00:14.0: Get port status 2-2 read: 0x2f0, return 0x2f0 [ 128.476366] usb usb2-port2: not warm reset yet, waiting 200ms [ 128.480332] xhci_hcd 0000:00:14.0: xhci_hub_status_data: stopping port polling. [ 128.484343] xhci_hcd 0000:00:14.0: Get port status 1-2 read: 0x2a0, return 0x100 [ 128.520323] xhci_hcd 0000:00:14.0: Get port status 1-2 read: 0x2a0, return 0x100 [ 128.556325] xhci_hcd 0000:00:14.0: Get port status 1-2 read: 0x2a0, return 0x100 [ 128.556353] usb usb1-port2: debounce total 125ms stable 100ms status 0x100 [ 128.556366] hub 1-0:1.0: state 7 ports 16 chg 0000 evt 0004 [ 128.556376] xhci_hcd 0000:00:14.0: Get port status 1-2 read: 0x2a0, return 0x100 [ 128.684329] xhci_hcd 0000:00:14.0: Get port status 2-2 read: 0x2f0, return 0x2f0 [ 128.684360] usb usb2-port2: not warm reset yet, waiting 200ms [ 128.892325] xhci_hcd 0000:00:14.0: Get port status 2-2 read: 0x2f0, return 0x2f0 [ 128.892357] usb usb2-port2: not warm reset yet, waiting 200ms [ 129.100317] xhci_hcd 0000:00:14.0: Get port status 2-2 read: 0x2f0, return 0x2f0 [ 129.100348] usb usb2-port2: not warm reset yet, waiting 200ms [ 129.100354] hub 2-0:1.0: port_wait_reset: err = -16 [ 129.100358] usb usb2-port2: not enabled, trying warm reset again... > > Kai-Heng > > > > > -Mathias
