On Wed, 21 Nov 2012, Sarah Sharp wrote:
> USB 3.0 hubs and roothubs will automatically transition a failed hot
> reset to a warm (BH) reset. In that case, the warm reset change bit
> will be set, and the link state change bit may also be set. Change
> hub_port_finish_reset to unconditionally clear those change bits for USB
> 3.0 hubs. If these bits are not cleared, we may lose port change events
> from the roothub.
>
> This commit should be backported to kernels as old as 3.2, that contain
> the commit 75d7cf72ab9fa01dc70877aa5c68e8ef477229dc "usbcore: refine
> warm reset logic".
>
> Signed-off-by: Sarah Sharp <sarah.a.sharp@xxxxxxxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> ---
> drivers/usb/core/hub.c | 6 +++---
> 1 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
> index a815fd2..7f8f10e 100644
> --- a/drivers/usb/core/hub.c
> +++ b/drivers/usb/core/hub.c
> @@ -2580,16 +2580,16 @@ static void hub_port_finish_reset(struct usb_hub *hub, int port1,
> clear_port_feature(hub->hdev,
> port1, USB_PORT_FEAT_C_RESET);
> /* FIXME need disconnect() for NOTATTACHED device */
> - if (warm) {
> + if (hub_is_superspeed(hub->hdev)) {
> clear_port_feature(hub->hdev, port1,
> USB_PORT_FEAT_C_BH_PORT_RESET);
> clear_port_feature(hub->hdev, port1,
> USB_PORT_FEAT_C_PORT_LINK_STATE);
It would be nice to avoid sending these requests (and the one above) if
the feature bits are already clear. Unfortunately that's a little
difficult to achieve the way the code is structured now. Some
refactoring may be in order.
Alan Stern
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