> On Dec 17, 2019, at 19:16, Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx> wrote: > > On 11.12.2019 17.08, Alan Stern wrote: >> On Wed, 11 Dec 2019, Kai-Heng Feng wrote: >>> >>> >>>> On Nov 30, 2019, at 01:41, Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx> wrote: >>>> >>>> On Dell TB16, Realtek USB ethernet (r8152) connects to an SMSC hub which >>>> then connects to ASMedia xHCI's root hub: >>>> >>>> /: Bus 04.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/2p, 5000M >>>> |__ Port 1: Dev 2, If 0, Class=Hub, Driver=hub/7p, 5000M >>>> |__ Port 2: Dev 3, If 0, Class=Vendor Specific Class, Driver=r8152, 5000M >>>> >>>> Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub >>>> Bus 004 Device 002: ID 0424:5537 Standard Microsystems Corp. USB5537B >>>> Bus 004 Device 003: ID 0bda:8153 Realtek Semiconductor Corp. RTL8153 Gigabit Ethernet Adapter >>>> >>>> The SMSC hub may disconnect after system resume from suspend. When this >>>> happens, the reset resume attempt fails, and the last resort to disable >>>> the port and see something comes up later, also fails. >>>> >>>> When the issue occurs, the link state stays in eSS.Disabled state >>>> despite the warm reset attempts. Accoding to spec this can be caused by >>>> invalid VBus, after some expiremets, the SMSC hub can be brought back >>>> after a powercycle. > > Could you open up a bit more how this happens, mainly codepaths how the > USB3 port ends up in eSS.Disabled state It happens right after hub_resume(), the first get_port_status(): Dec 23 09:46:58 u-XPS-13-9370 kernel: usb usb4: usb resume Dec 23 09:46:58 u-XPS-13-9370 kernel: hub 4-0:1.0: hub_resume Dec 23 09:46:58 u-XPS-13-9370 kernel: xhci_hcd 0000:3f:00.0: Get port status 4-1 read: 0x280, return 0x280 Dec 23 09:46:58 u-XPS-13-9370 kernel: usb usb4-port1: status 0280 change 0000 Dec 23 09:46:58 u-XPS-13-9370 kernel: xhci_hcd 0000:3f:00.0: Get port status 4-2 read: 0x2a0, return 0x2a0 Dec 23 09:46:58 u-XPS-13-9370 kernel: xhci_hcd 0000:3f:00.0: Get port status 4-1 read: 0x280, return 0x280 Dec 23 09:46:58 u-XPS-13-9370 kernel: xhci_hcd 0000:3f:00.0: Get port status 4-1 read: 0x280, return 0x280 Dec 23 09:46:58 u-XPS-13-9370 kernel: xhci_hcd 0000:3f:00.0: Get port status 4-1 read: 0x280, return 0x280 And it keeps getting 0x280. It should mean PP = 1 and PLS = 4, so it's in Disabled state. > > There might be something else wrong here. > My impression is that port should only end up in eSS.Disabled when directed > to with a Set_Port_Feature(PORT_LINK_STATE, eSS.Disabled) Request. > After this we shouldn't attempt warm resets, they won't work for USB3 ports in > ss.Disabled state. Do you suggest that we should power cycle the port in xHCI instead of USB core? Kai-Heng > > -Mathias
