From c70615740996823580bb8fb58461347b7ffaad9a Mon Sep 17 00:00:00 2001 From: Sarah Sharp Date: Mon, 6 Dec 2010 15:08:20 -0800 Subject: USB: Clear "warm" port reset change. In USB 3.0, there are two types of resets: a "hot" port reset and a "warm" port reset. The hot port reset is always tried first, and involves sending the reset signaling for a shorter amount of time. But sometimes devices don't respond to the hot reset, and a "Bigger Hammer" is needed. External hubs and roothubs will automatically try a warm reset when the hot reset fails, and they will set a status change bit to indicate when there is a "BH reset" change. Make sure the USB core clears that port status change bit, or we'll get lots of status change notifications on the interrupt endpoint of the USB 3.0 hub. (Side note: you may be confused why the USB 3.0 spec calls the same type of reset "warm reset" in some places and "BH reset" in other places. "BH" reset is supposed to stand for "Big Hammer" reset, but it also stands for "Brad Hosler". Brad died shortly after the USB 3.0 bus specification was started, and they decided to name the reset after him. The suggestion was made shortly before the spec was finalized, so the wording is a bit inconsistent.) Signed-off-by: Sarah Sharp --- drivers/usb/core/hub.c | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'drivers/usb') diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c index feb6e596c7c9..0eb27006f846 100644 --- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -3476,6 +3476,14 @@ static void hub_events(void) clear_port_feature(hdev, i, USB_PORT_FEAT_C_RESET); } + if ((portchange & USB_PORT_STAT_C_BH_RESET) && + hub_is_superspeed(hub->hdev)) { + dev_dbg(hub_dev, + "warm reset change on port %d\n", + i); + clear_port_feature(hdev, i, + USB_PORT_FEAT_C_BH_PORT_RESET); + } if (portchange & USB_PORT_STAT_C_LINK_STATE) { clear_port_feature(hub->hdev, i, USB_PORT_FEAT_C_PORT_LINK_STATE); -- cgit v1.2.3