From: Sean Nyekjaer sean@geanix.com

When suspending, and there is still CAN traffic on the interfaces the flexcan immediately wakes the platform again. As it should :-). But it throws this error msg:

[ 3169.378661] PM: noirq suspend of devices failed

On the way down to suspend the interface that throws the error message calls flexcan_suspend() but fails to call flexcan_noirq_suspend(). That means flexcan_enter_stop_mode() is called, but on the way out of suspend the driver only calls flexcan_resume() and skips flexcan_noirq_resume(), thus it doesn't call flexcan_exit_stop_mode(). This leaves the flexcan in stop mode, and with the current driver it can't recover from this even with a soft reboot, it requires a hard reboot.

This patch fixes the deadlock when using self wakeup, by calling flexcan_exit_stop_mode() from flexcan_resume() instead of flexcan_noirq_resume().

This also fixes another issue: CAN frames are received out-of-order in first IRQ handler run after wakeup.

The problem is that the wakeup latency from frame reception to the IRQ handler (where the CAN frames are sorted by timestamp) is much bigger than the time stamp counter wrap around time. This means it's impossible to sort the CAN frames by timestamp.

The reason is that the controller exits stop mode during noirq resume, which means it receives frames immediately, but interrupt handling is still not possible.

So exit stop mode during resume stage instead of noirq resume fixes this issue.

Fixes: de3578c198c6 ("can: flexcan: add self wakeup support") Signed-off-by: Sean Nyekjaer sean@geanix.com Tested-by: Sean Nyekjaer sean@geanix.com Signed-off-by: Joakim Zhang qiangqing.zhang@nxp.com Cc: linux-stable stable@vger.kernel.org # >= v5.0 Signed-off-by: Marc Kleine-Budde mkl@pengutronix.de --- drivers/net/can/flexcan.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c index a929cdda9ab2..b6f675a5e2d9 100644 --- a/drivers/net/can/flexcan.c +++ b/drivers/net/can/flexcan.c @@ -1722,6 +1722,9 @@ static int __maybe_unused flexcan_resume(struct device *device) netif_start_queue(dev); if (device_may_wakeup(device)) { disable_irq_wake(dev->irq); + err = flexcan_exit_stop_mode(priv); + if (err) + return err; } else { err = pm_runtime_force_resume(device); if (err) @@ -1767,14 +1770,9 @@ static int __maybe_unused flexcan_noirq_resume(struct device *device) { struct net_device *dev = dev_get_drvdata(device); struct flexcan_priv *priv = netdev_priv(dev); - int err;

- if (netif_running(dev) && device_may_wakeup(device)) { + if (netif_running(dev) && device_may_wakeup(device)) flexcan_enable_wakeup_irq(priv, false); - err = flexcan_exit_stop_mode(priv); - if (err) - return err; - }

return 0; }