[PATCH v2 08/15] can: kvaser_usb_leaf: Fix TX queue out of sync after restart

[Jimmy Assarsson <extja@kvaser.com>]

From: Anssi Hannula <anssi.hannula@bitwise.fi>

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.

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")
Tested-by: Jimmy Assarsson <extja@kvaser.com>
Signed-off-by: Anssi Hannula <anssi.hannula@bitwise.fi>
---
Changes in v2:
  - Rebased on b3b6df2c56d8 ("can: kvaser_usb: kvaser_usb_leaf: fix bittiming limits")
  - Removed explicit queue flush.

 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 | 2 ++
 3 files changed, 5 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 eefcbe3aadce..d018cb5adf83 100644
--- a/drivers/net/can/usb/kvaser_usb/kvaser_usb.h
+++ b/drivers/net/can/usb/kvaser_usb/kvaser_usb.h
@@ -177,6 +177,8 @@ 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 d1401a2d23e9..17d4bbcee831 100644
--- a/drivers/net/can/usb/kvaser_usb/kvaser_usb_core.c
+++ b/drivers/net/can/usb/kvaser_usb/kvaser_usb_core.c
@@ -461,7 +461,7 @@ 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 8f9e2707998d..1bc0350d623b 100644
--- a/drivers/net/can/usb/kvaser_usb/kvaser_usb_leaf.c
+++ b/drivers/net/can/usb/kvaser_usb/kvaser_usb_leaf.c
@@ -1660,6 +1660,8 @@ static int kvaser_usb_leaf_set_mode(struct net_device *netdev,
 
 	switch (mode) {
 	case CAN_MODE_START:
+		kvaser_usb_unlink_tx_urbs(priv);
+
 		err = kvaser_usb_leaf_simple_cmd_async(priv, CMD_START_CHIP);
 		if (err)
 			return err;
-- 
2.36.1