On Fri, Aug 26, 2022 at 03:58:39PM +0800, Ray Chi wrote:
> If a broken accessory connected to a USB host, usbcore might
> keep doing enumeration retries and it will take a long time to
> cause system unstable.
>
> This patch provides a quirk to specific USB ports of the hub to
> stop USB enumeration if needed.
Why only to specific ports?
> Signed-off-by: Ray Chi <raychi@xxxxxxxxxx>
> ---
> drivers/usb/core/hub.c | 33 +++++++++++++++++++++++++++++++++
> include/linux/usb.h | 3 +++
> 2 files changed, 36 insertions(+)
>
> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
> index 2633acde7ac1..0f4097440ffb 100644
> --- a/drivers/usb/core/hub.c
> +++ b/drivers/usb/core/hub.c
> @@ -3081,6 +3081,28 @@ static int hub_port_reset(struct usb_hub *hub, int port1,
> return status;
> }
>
> +/* Stop enumerate if the port met errors and quirk is set */
> +static bool hub_port_stop_enumerate(struct usb_hub *hub, int port1, int retries)
> +{
> + struct usb_port *port_dev = hub->ports[port1 - 1];
> + struct usb_device *hdev = hub->hdev;
> +
> + if (retries < (PORT_INIT_TRIES - 1) / 2)
> + return false;
> +
> + /*
> + * Some USB hosts can't take a long time to keep doing enumeration
> + * retry. After doing half of the retries, we would turn off the port
> + * power to stop enumeration if the quirk is set.
> + */
> + if (port_dev->quirks & USB_PORT_QUIRK_STOP_ENUM) {
> + usb_hub_set_port_power(hdev, hub, port1, false);
Why turn the port power off? Aren't there better ways to stop the
enumeration attempts? When will the power ever get turned back on?
Why not use the initial_descriptor_timeout module parameter for this
purpose? That's the sort of thing it was meant for.
Alan Stern
