linux-kernel - [PATCH 3.16.y-ckt 108/135] can: kvaser_usb: Retry the first bulk transfer on -ETIMEDOUT

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Message-Id: <1423224113-10958-109-git-send-email-luis.henriques@canonical.com>
Date:	Fri,  6 Feb 2015 12:01:26 +0000
From:	Luis Henriques <luis.henriques@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	"Ahmed S. Darwish" <ahmed.darwish@...eo.com>,
	Marc Kleine-Budde <mkl@...gutronix.de>,
	Luis Henriques <luis.henriques@...onical.com>
Subject: [PATCH 3.16.y-ckt 108/135] can: kvaser_usb: Retry the first bulk transfer on -ETIMEDOUT

3.16.7-ckt6 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: "Ahmed S. Darwish" <ahmed.darwish@...eo.com>

commit 14c10c2a1dd8eb8e00b750b521753260befa2789 upstream.

On some x86 laptops, plugging a Kvaser device again after an
unplug makes the firmware always ignore the very first command.
For such a case, provide some room for retries instead of
completely exiting the driver init code.

Signed-off-by: Ahmed S. Darwish <ahmed.darwish@...eo.com>
Signed-off-by: Marc Kleine-Budde <mkl@...gutronix.de>
Signed-off-by: Luis Henriques <luis.henriques@...onical.com>
---
 drivers/net/can/usb/kvaser_usb.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/net/can/usb/kvaser_usb.c b/drivers/net/can/usb/kvaser_usb.c
index 30067d464bd3..f85f02150877 100644
--- a/drivers/net/can/usb/kvaser_usb.c
+++ b/drivers/net/can/usb/kvaser_usb.c
@@ -1588,7 +1588,7 @@ static int kvaser_usb_probe(struct usb_interface *intf,
 {
 	struct kvaser_usb *dev;
 	int err = -ENOMEM;
-	int i;
+	int i, retry = 3;
 
 	dev = devm_kzalloc(&intf->dev, sizeof(*dev), GFP_KERNEL);
 	if (!dev)
@@ -1606,7 +1606,15 @@ static int kvaser_usb_probe(struct usb_interface *intf,
 
 	usb_set_intfdata(intf, dev);
 
-	err = kvaser_usb_get_software_info(dev);
+	/* On some x86 laptops, plugging a Kvaser device again after
+	 * an unplug makes the firmware always ignore the very first
+	 * command. For such a case, provide some room for retries
+	 * instead of completely exiting the driver.
+	 */
+	do {
+		err = kvaser_usb_get_software_info(dev);
+	} while (--retry && err == -ETIMEDOUT);
+
 	if (err) {
 		dev_err(&intf->dev,
 			"Cannot get software infos, error %d\n", err);
-- 
2.1.4

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