> 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.
>
> So let's power cycle the port at the end of reset resume attempt, if
> it's in eSS.Disabled state.
If there's no objection, can this fix be reviewed and merged?
Kai-Heng
>
> Signed-off-by: Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx>
> ---
> v2:
> - Lower dev_info() to dev_dbg().
>
> drivers/usb/core/hub.c | 16 ++++++++++++++++
> 1 file changed, 16 insertions(+)
>
> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
> index 6b6cd76ac5e6..a2e6001046f5 100644
> --- a/drivers/usb/core/hub.c
> +++ b/drivers/usb/core/hub.c
> @@ -2739,6 +2739,18 @@ static bool hub_port_warm_reset_required(struct usb_hub *hub, int port1,
> || link_state == USB_SS_PORT_LS_COMP_MOD;
> }
>
> +static bool hub_port_power_cycle_required(struct usb_hub *hub, int port1,
> + u16 portstatus)
> +{
> + u16 link_state;
> +
> + if (!hub_is_superspeed(hub->hdev))
> + return false;
> +
> + link_state = portstatus & USB_PORT_STAT_LINK_STATE;
> + return link_state == USB_SS_PORT_LS_SS_DISABLED;
> +}
> +
> static void hub_port_power_cycle(struct usb_hub *hub, int port1)
> {
> struct usb_port *port_dev = hub->ports[port1 - 1];
> @@ -3601,6 +3613,10 @@ int usb_port_resume(struct usb_device *udev, pm_message_t msg)
> if (status < 0) {
> dev_dbg(&udev->dev, "can't resume, status %d\n", status);
> hub_port_logical_disconnect(hub, port1);
> + if (hub_port_power_cycle_required(hub, port1, portstatus)) {
> + dev_dbg(&udev->dev, "device in disabled state, attempt power cycle\n");
> + hub_port_power_cycle(hub, port1);
> + }
> } else {
> /* Try to enable USB2 hardware LPM */
> usb_enable_usb2_hardware_lpm(udev);
> --
> 2.17.1
>
