[PATCH] usb: hub: fix state change check for not powercycled ports

[Ahmad Fatoum]

Hello,

On 18.01.21 20:09, Michael Grzeschik wrote:
> Since we don't power cycle the ports on start since patch "19bb0b2a usb:
> hub: Do not power-cycle usb devices on init" it is possible that the
> device on this port is already active from a previous enumeration. This
> way barebox will never get any change in USB_PORT_STAT_C_CONNECTION bit
> change.
> 
> Although the device will probably still work fine after the following
> port reset, the current code will always miss reenumerating these still
> plugged devices. This patch fixes this by ignoring the check for
> STAT_C_CONNECTION bit and only go for USB_PORT_STAT_CONNECTION which
> should be enough.

This breaks USB enumeration for me on an i.MX6Q. The USB flash driver behind
the hub is detected twice, which barebox doesn't like at all:

barebox at Embest MarS Board i.MX6Dual:/ usb -s
usb: USB: scanning bus for devices...
usb1: Bus 001 Device 001: ID 0000:0000 EHCI Host Controller
usb1-0: Bus 001 Device 002: ID 1a40:0101 USB 2.0 Hub [MTT]
usb1-0-1: Bus 001 Device 003: ID 058f:6387 Mass Storage
Using index 0 for the new disk
usb1-0-1: Bus 001 Device 004: ID 058f:6387 Mass Storage
ERROR: register_device: already registered usb1-0-1
ERROR: usb1-0-1: Failed to register device: Invalid argument
usb: 3 USB Device(s) found
Bus 001 Device 001: ID 0000:0000 EHCI Host Controller
Bus 001 Device 002: ID 1a40:0101 USB 2.0 Hub [MTT]
Bus 001 Device 003: ID 058f:6387 Mass Storage

This seems to corrupt some internal barebox state as reading
/dev/disk0.0 will hang. Reading /dev/disk0 is fine however.

With this patch reverted it however works:

usb: USB: scanning bus for devices...
usb1: Bus 001 Device 001: ID 0000:0000 EHCI Host Controller
usb1-0: Bus 001 Device 002: ID 1a40:0101 USB 2.0 Hub [MTT]
usb1-0-1: Bus 001 Device 003: ID 058f:6387 Mass Storage
Using index 0 for the new disk
usb: 3 USB Device(s) found
Bus 001 Device 001: ID 0000:0000 EHCI Host Controller
Bus 001 Device 002: ID 1a40:0101 USB 2.0 Hub [MTT]
Bus 001 Device 003: ID 058f:6387 Mass Storage

The USB drive is not self-powered. It doesn't make a difference
whether it's done directly after cold reset or:
  usb -s
  boot bnet
  usb -s

Cheers,
Ahmad


> 
> Signed-off-by: Michael Grzeschik <m.grzeschik at pengutronix.de>
> ---
>  drivers/usb/core/hub.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
> index 01653d8c20..d1112248ee 100644
> --- a/drivers/usb/core/hub.c
> +++ b/drivers/usb/core/hub.c
> @@ -336,8 +336,7 @@ static void usb_scan_port(struct usb_device_scan *usb_scan)
>  	dev_dbg(&dev->dev, "port%d: Status 0x%04x Change 0x%04x\n",
>  			port + 1, portstatus, portchange);
>  
> -	if (!(portchange & USB_PORT_STAT_C_CONNECTION) ||
> -	    !(portstatus & USB_PORT_STAT_CONNECTION)) {
> +	if (!(portstatus & USB_PORT_STAT_CONNECTION)) {
>  		if (get_time_ns() >= hub->connect_timeout) {
>  			dev_dbg(&dev->dev, "port%d: timeout\n", port + 1);
>  			/* Remove this device from scanning list */
> 

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