On Thu, 18 Oct 2018, Kai-Heng Feng wrote:
> Devices connected under Terminus Technology Inc. Hub (1a40:0101) may
> fail to work after the system resumes from suspend:
> [ 206.063325] usb 3-2.4: reset full-speed USB device number 4 using xhci_hcd
> [ 206.143691] usb 3-2.4: device descriptor read/64, error -32
> [ 206.351671] usb 3-2.4: device descriptor read/64, error -32
>
> Info for this hub:
> T: Bus=03 Lev=01 Prnt=01 Port=01 Cnt=01 Dev#= 2 Spd=480 MxCh= 4
> D: Ver= 2.00 Cls=09(hub ) Sub=00 Prot=01 MxPS=64 #Cfgs= 1
> P: Vendor=1a40 ProdID=0101 Rev=01.11
> S: Product=USB 2.0 Hub
> C: #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr=100mA
> I: If#= 0 Alt= 0 #EPs= 1 Cls=09(hub ) Sub=00 Prot=00 Driver=hub
>
> Some expirements indicate that the USB devices connected to the hub are
> innocent, it's the hub itself is to blame. The hub needs extra delay
> time after it resets its port.
>
> Hence wait for extra delay, if the device is connected to this quirky
> hub.
> --- a/drivers/usb/core/hub.c
> +++ b/drivers/usb/core/hub.c
> @@ -2891,6 +2891,11 @@ static int hub_port_reset(struct usb_hub *hub, int port1,
> if (udev) {
> struct usb_hcd *hcd = bus_to_hcd(udev->bus);
>
> + /* Hub needs extra delay after resetting its port. */
> + if (udev->parent &&
> + udev->parent->quirks & USB_QUIRK_HUB_SLOW_RESET)
There's no need to test udev->parent, or even to put this code under
the "if (udev)" test. You should simply use hub->hdev instead; it will
always be defined.
Alan Stern
> + msleep(100);
> +
> update_devnum(udev, 0);
> /* The xHC may think the device is already reset,
> * so ignore the status.
