linux-kernel - [PATCH AUTOSEL 4.20 122/304] usb: hub: delay hub autosuspend if USB3 port is still link training

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Date:   Mon, 28 Jan 2019 10:40:39 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Mathias Nyman <mathias.nyman@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Sasha Levin <sashal@...nel.org>, linux-usb@...r.kernel.org
Subject: [PATCH AUTOSEL 4.20 122/304] usb: hub: delay hub autosuspend if USB3 port is still link training

From: Mathias Nyman <mathias.nyman@...ux.intel.com>

[ Upstream commit e86108940e541febf35813402ff29fa6f4a9ac0b ]

When initializing a hub we want to give a USB3 port in link training
the same debounce delay time before autosuspening the hub as already
trained, connected enabled ports.

USB3 ports won't reach the enabled state with "current connect status" and
"connect status change" bits set until the USB3 link training finishes.

Catching the port in link training (polling) and adding the debounce delay
prevents unnecessary failed attempts to autosuspend the hub.

Signed-off-by: Mathias Nyman <mathias.nyman@...ux.intel.com>
Acked-by: Alan Stern <stern@...land.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/usb/core/hub.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index f76b2e0aba9d..1d1e61e980f3 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -1112,6 +1112,16 @@ static void hub_activate(struct usb_hub *hub, enum hub_activation_type type)
 						   USB_PORT_FEAT_ENABLE);
 		}
 
+		/*
+		 * Add debounce if USB3 link is in polling/link training state.
+		 * Link will automatically transition to Enabled state after
+		 * link training completes.
+		 */
+		if (hub_is_superspeed(hdev) &&
+		    ((portstatus & USB_PORT_STAT_LINK_STATE) ==
+						USB_SS_PORT_LS_POLLING))
+			need_debounce_delay = true;
+
 		/* Clear status-change flags; we'll debounce later */
 		if (portchange & USB_PORT_STAT_C_CONNECTION) {
 			need_debounce_delay = true;
-- 
2.19.1