On Thu, Mar 07, 2013 at 04:24:27PM -0800, Sarah Sharp wrote:
> [This is upstream commit d3b9d7a9051d7024a93c76a84b2f84b3b66ad6d5.
> It needs to be backported to kernels as old as 3.2, because it fixes the
> buggy commit 9dbcaec830cd97f44a0b91b315844e0d7144746b "USB: Handle warm
> reset failure on empty port."]
> 
> A USB 3.0 device can transition to the Inactive state if a U1 or U2 exit
> transition fails.  The current code in hub_events simply issues a warm
> reset, but does not call any pre-reset or post-reset driver methods (or
> unbind/rebind drivers without them).  Therefore the drivers won't know
> their device has just been reset.
> 
> hub_events should instead call usb_reset_device.  This means
> hub_port_reset now needs to figure out whether it should issue a warm
> reset or a hot reset.
> 
> Remove the FIXME note about needing disconnect() for a NOTATTACHED
> device.  This patch fixes that.
> 
> Signed-off-by: Sarah Sharp <[email protected]>
> Acked-by: Alan Stern <[email protected]>
> Cc: [email protected]
> ---
>  drivers/usb/core/hub.c |   30 +++++++++++++++++++++++++-----
>  1 files changed, 25 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
> index 727c784..29c941f 100644
> --- a/drivers/usb/core/hub.c
> +++ b/drivers/usb/core/hub.c
> @@ -2274,7 +2274,6 @@ static void hub_port_finish_reset(struct usb_hub *hub, 
> int port1,
>       case -ENODEV:
>               clear_port_feature(hub->hdev,
>                               port1, USB_PORT_FEAT_C_RESET);
> -             /* FIXME need disconnect() for NOTATTACHED device */
>               if (hub_is_superspeed(hub->hdev)) {
>                       clear_port_feature(hub->hdev, port1,
>                                       USB_PORT_FEAT_C_BH_PORT_RESET);
> @@ -2308,6 +2307,18 @@ static int hub_port_reset(struct usb_hub *hub, int 
> port1,
>                * Some companion controllers don't like it when they mix.
>                */
>               down_read(&ehci_cf_port_reset_rwsem);
> +     } else if (!warm) {
> +             /*
> +              * If the caller hasn't explicitly requested a warm reset,
> +              * double check and see if one is needed.
> +              */
> +             status = hub_port_status(hub, port1,
> +                                     &portstatus, &portchange);
> +             if (status < 0)
> +                     goto done;
> +
> +             if (hub_port_warm_reset_required(hub, portstatus))
> +                     warm = true;
>       }
>  
>       /* Reset the port */
> @@ -3866,12 +3877,21 @@ static void hub_events(void)
>                        */
>                       if (hub_port_warm_reset_required(hub, portstatus)) {
>                               int status;
> +                             struct usb_device *udev =
> +                                     hub->ports[i - 1]->child;

I believe the ->ports[] field isn't present in this stable kernel, and
3.4 will fail to compile (same is true for 3.5 and 3.2).

Cheers,
--
Luis

>  
>                               dev_dbg(hub_dev, "warm reset port %d\n", i);
> -                             status = hub_port_reset(hub, i, NULL,
> -                                             HUB_BH_RESET_TIME, true);
> -                             if (status < 0)
> -                                     hub_port_disable(hub, i, 1);
> +                             if (!udev) {
> +                                     status = hub_port_reset(hub, i,
> +                                                     NULL, HUB_BH_RESET_TIME,
> +                                                     true);
> +                                     if (status < 0)
> +                                             hub_port_disable(hub, i, 1);
> +                             } else {
> +                                     usb_lock_device(udev);
> +                                     status = usb_reset_device(udev);
> +                                     usb_unlock_device(udev);
> +                             }
>                               connect_change = 0;
>                       }
>  
> -- 
> 1.7.9
> 
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