linux-kernel - Re: [PATCH v3] usb: core: Bail out when port is stuck in reset loop

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Date:   Mon, 17 Jan 2022 11:00:05 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     gregkh@...uxfoundation.org
Cc:     stern@...land.harvard.edu, mathias.nyman@...ux.intel.com,
        Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
        Bixuan Cui <cuibixuan@...wei.com>,
        Rajat Jain <rajatja@...gle.com>, Andrew Lunn <andrew@...n.ch>,
        Chris Chiu <chris.chiu@...onical.com>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] usb: core: Bail out when port is stuck in reset loop

On Thu, Dec 30, 2021 at 1:28 PM Kai-Heng Feng
<kai.heng.feng@...onical.com> wrote:
>
> Unplugging USB device may cause an incorrect warm reset loop and the
> port can no longer be used:
> [  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 port status is PP=1, CCS=0, PED=0, PLS=Inactive, which is Error
> state per "USB3 Root Hub Port State Machine". It's reasonable to perform
> warm reset several times, but if the port is still not enabled after
> many attempts, consider it's gone and treat it as disconnected.
>
> Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>

A gentle ping...

> ---
>  drivers/usb/core/hub.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
> index 00070a8a65079..f618d86d526d1 100644
> --- a/drivers/usb/core/hub.c
> +++ b/drivers/usb/core/hub.c
> @@ -2979,7 +2979,8 @@ static int hub_port_reset(struct usb_hub *hub, int port1,
>                 }
>
>                 /* Check for disconnect or reset */
> -               if (status == 0 || status == -ENOTCONN || status == -ENODEV) {
> +               if (status == 0 || status == -ENOTCONN || status == -ENODEV ||
> +                   (status == -EBUSY && i == PORT_RESET_TRIES - 1)) {
>                         usb_clear_port_feature(hub->hdev, port1,
>                                         USB_PORT_FEAT_C_RESET);
>
> --
> 2.33.1
>