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From:   Anssi Hannula <anssi.hannula@bitwise.fi>
To:     Jimmy Assarsson <extja@kvaser.com>
Cc:     linux-can@vger.kernel.org, Marc Kleine-Budde <mkl@pengutronix.de>,
        linux-kernel@vger.kernel.org
Subject: [PATCH 06/12] can: kvaser_usb_leaf: Fix TX queue out of sync after restart
Date:   Mon, 16 May 2022 16:47:42 +0300
Message-Id: <20220516134748.3724796-7-anssi.hannula@bitwise.fi>
In-Reply-To: <20220516134748.3724796-1-anssi.hannula@bitwise.fi>
References: <20220516134748.3724796-1-anssi.hannula@bitwise.fi>
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The TX queue seems to be implicitly flushed by the hardware during
bus-off or bus-off recovery, but the driver does not reset the TX
bookkeeping.

Despite not resetting TX bookkeeping the driver still re-enables TX
queue unconditionally, leading to "cannot find free context" /
NETDEV_TX_BUSY errors if the TX queue was full at bus-off time.

Fix that by resetting TX bookkeeping on CAN restart.

Also, add an explicit queue flush in case some hardware versions do not
do that implicitly.

Tested with 0bfd:0124 Kvaser Mini PCI Express 2xHS FW 4.18.778.

Fixes: 080f40a6fa28 ("can: kvaser_usb: Add support for Kvaser CAN/USB devices")
Signed-off-by: Anssi Hannula <anssi.hannula@bitwise.fi>
---
 drivers/net/can/usb/kvaser_usb/kvaser_usb.h      | 2 ++
 drivers/net/can/usb/kvaser_usb/kvaser_usb_core.c | 2 +-
 drivers/net/can/usb/kvaser_usb/kvaser_usb_leaf.c | 6 ++++++
 3 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/net/can/usb/kvaser_usb/kvaser_usb.h b/drivers/net/can/usb/kvaser_usb/kvaser_usb.h
index 3a49257f9fa6..f1bea13a3829 100644
--- a/drivers/net/can/usb/kvaser_usb/kvaser_usb.h
+++ b/drivers/net/can/usb/kvaser_usb/kvaser_usb.h
@@ -175,6 +175,8 @@ struct kvaser_usb_dev_cfg {
 extern const struct kvaser_usb_dev_ops kvaser_usb_hydra_dev_ops;
 extern const struct kvaser_usb_dev_ops kvaser_usb_leaf_dev_ops;
 
+void kvaser_usb_unlink_tx_urbs(struct kvaser_usb_net_priv *priv);
+
 int kvaser_usb_recv_cmd(const struct kvaser_usb *dev, void *cmd, int len,
 			int *actual_len);
 
diff --git a/drivers/net/can/usb/kvaser_usb/kvaser_usb_core.c b/drivers/net/can/usb/kvaser_usb/kvaser_usb_core.c
index 7388fdca9079..a8d72fb8291a 100644
--- a/drivers/net/can/usb/kvaser_usb/kvaser_usb_core.c
+++ b/drivers/net/can/usb/kvaser_usb/kvaser_usb_core.c
@@ -440,7 +440,7 @@ static void kvaser_usb_reset_tx_urb_contexts(struct kvaser_usb_net_priv *priv)
 /* This method might sleep. Do not call it in the atomic context
  * of URB completions.
  */
-static void kvaser_usb_unlink_tx_urbs(struct kvaser_usb_net_priv *priv)
+void kvaser_usb_unlink_tx_urbs(struct kvaser_usb_net_priv *priv)
 {
 	usb_kill_anchored_urbs(&priv->tx_submitted);
 	kvaser_usb_reset_tx_urb_contexts(priv);
diff --git a/drivers/net/can/usb/kvaser_usb/kvaser_usb_leaf.c b/drivers/net/can/usb/kvaser_usb/kvaser_usb_leaf.c
index d7f2d64a8083..2d30a662edb5 100644
--- a/drivers/net/can/usb/kvaser_usb/kvaser_usb_leaf.c
+++ b/drivers/net/can/usb/kvaser_usb/kvaser_usb_leaf.c
@@ -1402,6 +1402,12 @@ static int kvaser_usb_leaf_set_mode(struct net_device *netdev,
 
 	switch (mode) {
 	case CAN_MODE_START:
+		err = kvaser_usb_leaf_flush_queue(priv);
+		if (err)
+			return err;
+
+		kvaser_usb_unlink_tx_urbs(priv);
+
 		err = kvaser_usb_leaf_simple_cmd_async(priv, CMD_START_CHIP);
 		if (err)
 			return err;
-- 
2.34.1