linux-kernel - [PATCH] usb: core: Check portchange C_PORT

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Message-Id: <20181003051822.4011-1-kai.heng.feng@canonical.com>
Date:   Wed,  3 Oct 2018 13:18:22 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     gregkh@...uxfoundation.org
Cc:     stern@...land.harvard.edu, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Kai-Heng Feng <kai.heng.feng@...onical.com>
Subject: [PATCH] usb: core: Check portchange C_PORT_RESET after resetting

Based on USB2.0 Spec Section 11.24.2.7.2.5:

  "This bit is set when the port transitions from the Resetting state (or,
  if present, the Speed_eval state) to the Enabled state."

Also Section 11.24.2.13:

  "Setting the reset feature PORT_RESET causes the hub to signal reset on
  that port. When the reset signaling is complete, the hub sets the
  C_PORT_RESET status change and immediately enables the port."

So let's also check C_PORT_RESET for reset completion.

Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
---
 drivers/usb/core/hub.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 7801bb30bdba..d96058372280 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -2721,7 +2721,8 @@ static int hub_port_wait_reset(struct usb_hub *hub, int port1,
 		 * so also wait for the connection to be re-established.
 		 */
 		if (!(portstatus & USB_PORT_STAT_RESET) &&
-		    (portstatus & USB_PORT_STAT_CONNECTION))
+		    (portstatus & USB_PORT_STAT_CONNECTION) &&
+		    (portchange & USB_PORT_STAT_C_RESET))
 			break;
 
 		/* switch to the long delay after two short delay failures */
-- 
2.17.1