[PATCH 5.4 099/158] can: flexcan: flexcan_chip_start(): fix erroneous flexcan_transceiver_enable() during bus-off recovery

Greg Kroah-Hartman
2020-11-23T12:38:39Z

From: Marc Kleine-Budde <mkl@pengutronix.de>

[ Upstream commit cd9f13c59461351d7a5fd07924264fb49b287359 ]

If the CAN controller goes into bus off, the do_set_mode() callback with
CAN_MODE_START can be used to recover the controller, which then calls
flexcan_chip_start(). If configured, this is done automatically by the
framework or manually by the user.

In flexcan_chip_start() there is an explicit call to
flexcan_transceiver_enable(), which does a regulator_enable() on the
transceiver regulator. This results in a net usage counter increase, as there
is no corresponding flexcan_transceiver_disable() in the bus off code path.
This further leads to the transceiver stuck enabled, even if the CAN interface
is shut down.

To fix this problem the
flexcan_transceiver_enable()/flexcan_transceiver_disable() are moved out of
flexcan_chip_start()/flexcan_chip_stop() into flexcan_open()/flexcan_close().

Fixes: e955cead0311 ("CAN: Add Flexcan CAN controller driver")
Link: https://lore.kernel.org/r/20201118150148.2664024-1-mkl@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/can/flexcan.c | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c
index b22cd8d14716a..1bd955e4c7d66 100644
--- a/drivers/net/can/flexcan.c
+++ b/drivers/net/can/flexcan.c
@@ -1202,14 +1202,10 @@ static int flexcan_chip_start(struct net_device *dev)
priv->write(reg_mecr, &regs->mecr);
}

- err = flexcan_transceiver_enable(priv);
- if (err)
- goto out_chip_disable;
-
/* synchronize with the can bus */
err = flexcan_chip_unfreeze(priv);
if (err)
- goto out_transceiver_disable;
+ goto out_chip_disable;

priv->can.state = CAN_STATE_ERROR_ACTIVE;

@@ -1226,8 +1222,6 @@ static int flexcan_chip_start(struct net_device *dev)

return 0;

- out_transceiver_disable:
- flexcan_transceiver_disable(priv);
out_chip_disable:
flexcan_chip_disable(priv);
return err;
@@ -1257,7 +1251,6 @@ static int __flexcan_chip_stop(struct net_device *dev, bool disable_on_error)
priv->write(priv->reg_ctrl_default & ~FLEXCAN_CTRL_ERR_ALL,
&regs->ctrl);

- flexcan_transceiver_disable(priv);
priv->can.state = CAN_STATE_STOPPED;

return 0;
@@ -1293,10 +1286,14 @@ static int flexcan_open(struct net_device *dev)
if (err)
goto out_runtime_put;

- err = request_irq(dev->irq, flexcan_irq, IRQF_SHARED, dev->name, dev);
+ err = flexcan_transceiver_enable(priv);
if (err)
goto out_close;

+ err = request_irq(dev->irq, flexcan_irq, IRQF_SHARED, dev->name, dev);
+ if (err)
+ goto out_transceiver_disable;
+
priv->mb_size = sizeof(struct flexcan_mb) + CAN_MAX_DLEN;
priv->mb_count = (sizeof(priv->regs->mb[0]) / priv->mb_size) +
(sizeof(priv->regs->mb[1]) / priv->mb_size);
@@ -1352,6 +1349,8 @@ static int flexcan_open(struct net_device *dev)
can_rx_offload_del(&priv->offload);
out_free_irq:
free_irq(dev->irq, dev);
+ out_transceiver_disable:
+ flexcan_transceiver_disable(priv);
out_close:
close_candev(dev);
out_runtime_put:
@@ -1370,6 +1369,7 @@ static int flexcan_close(struct net_device *dev)

can_rx_offload_del(&priv->offload);
free_irq(dev->irq, dev);
+ flexcan_transceiver_disable(priv);

close_candev(dev);
pm_runtime_put(priv->dev);
--
2.27.0