On 16/08/2019 10.20, Joakim Zhang wrote:
As reproted by Sean Nyekjaer below:
When suspending, when 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 does
call flexcan_suspend but fails to call flexcan_noirq_suspend. That means the
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.
The best way to exit stop mode is in Wake Up interrupt context, and then
suspend() and resume() functions can be symmetric. However, stop mode
request and ack will be controlled by SCU(System Control Unit) firmware(manage
clock,power,stop mode, etc. by Cortex-M4 core) in coming i.MX8(QM/QXP). And SCU
firmware interface can't be available in interrupt context.
For compatibillity, the wake up mechanism can't be symmetric, so we need
in_stop_mode hack.
Fixes: de3578c198c6 ("can: flexcan: add self wakeup support")
Reported-by: Sean Nyekjaer <sean@xxxxxxxxxx>
Signed-off-by: Joakim Zhang <qiangqing.zhang@xxxxxxx>
Unfortunatly it's still possible to reproduce the deadlock with this
patch...
[ 689.921717] flexcan: probe of 2094000.flexcan failed with error -110
My test setup:
PC with CAN-USB dongle connected to can0 and can1.
PC:
$ while true; do cansend can0 '123#DEADBEEF'; done
iMX6ull:
root@iwg26:~# systemctl suspend
[ 365.858054] systemd[1]: Reached target Sleep.
root@iwg26:~# [ 365.939826] systemd[1]: Starting Suspend...
[ 366.115839] systemd-sleep[248]: Suspending system...
[ 366.517949] dpm_run_callback(): platform_pm_suspend+0x0/0x5c returns -110
[ 366.518249] PM: Device 2094000.flexcan failed to suspend: error -110
[ 366.518406] PM: Some devices failed to suspend, or early wake event
detected
[ 366.732162] dpm_run_callback(): platform_pm_suspend+0x0/0x5c returns -110
[ 366.732285] PM: Device 2090000.flexcan failed to suspend: error -110
[ 366.732330] PM: Some devices failed to suspend, or early wake event
detected
[ 366.890637] systemd-sleep[248]: System resumed.
[ 366.923062] systemd[1]: Started Suspend.
[ 366.942819] systemd[1]: sleep.target: Unit not needed anymore. Stopping.
[ 366.954791] systemd[1]: Stopped target Sleep.
[ 366.962402] systemd[1]: Reached target Suspend.
[ 366.977546] systemd-logind[135]: Operation 'sleep' finished.
[ 366.979194] systemd[1]: suspend.target: Unit not needed anymore.
Stopping.
[ 366.993831] systemd[1]: Stopped target Suspend.
[ 367.139972] systemd-networkd[220]: usb0: Lost carrier
[ 367.294077] systemd-networkd[220]: usb0: Gained carrier
root@iwg26:~# candump can0 | head -n 2
can0 123 [4] DE AD BE EF
can0 123 [4] DE AD BE EF
root@iwg26:~# candump can1 | head -n 2
can1 123 [4] DE AD BE EF
can1 123 [4] DE AD BE EF
root@iwg26:~# systemctl suspend
root@iwg26:~# [ 385.106658] systemd[1]: Reached target Sleep.
[ 385.147602] systemd[1]: Starting Suspend...
[ 385.246421] systemd-sleep[260]: Suspending system...
[ 385.634733] dpm_run_callback(): platform_pm_suspend+0x0/0x5c returns -110
[ 385.634855] PM: Device 2090000.flexcan failed to suspend: error -110
[ 385.634897] PM: Some devices failed to suspend, or early wake event
detected
[ 385.856251] PM: noirq suspend of devices failed
[ 385.998364] systemd-sleep[260]: System resumed.
[ 386.023390] systemd[1]: Started Suspend.
[ 386.031570] systemd[1]: sleep.target: Unit not needed anymore. Stopping.
[ 386.055886] systemd[1]: Stopped target Sleep.
[ 386.061430] systemd[1]: Reached target Suspend.
[ 386.066142] systemd[1]: suspend.target: Unit not needed anymore.
Stopping.
[ 386.112575] systemd-networkd[220]: usb0: Lost carrier
[ 386.116797] systemd-logind[135]: Operation 'sleep' finished.
[ 386.146161] systemd[1]: Stopped target Suspend.
[ 386.260866] systemd-networkd[220]: usb0: Gained carrier
root@iwg26:~# candump can0 | head -n 2
can0 123 [4] DE AD BE EF
can0 123 [4] DE AD BE EF
root@iwg26:~# candump can1 | head -n 2
can1 123 [4] DE AD BE EF
can1 123 [4] DE AD BE EF
root@iwg26:~# systemctl suspend
[ 396.919303] systemd[1]: Reached target Sleep.
root@iwg26:~# [ 396.964722] systemd[1]: Starting Suspend...
[ 397.067336] systemd-sleep[268]: Suspending system...
[ 397.574571] PM: noirq suspend of devices failed
[ 397.834731] PM: noirq suspend of devices failed
[ 397.807996] systemd-networkd[220]: usb0: Lost carrier
[ 398.156295] dpm_run_callback(): platform_pm_suspend+0x0/0x5c returns -110
[ 398.156339] PM: Device 2094000.flexcan failed to suspend: error -110
[ 398.156509] PM: Some devices failed to suspend, or early wake event
detected
[ 398.053555] systemd-sleep[268]: Failed to write /sys/power/state:
Device or resource busy
[ 398.074751] systemd[1]: systemd-suspend.service: Main process exited,
code=exited, status=1/FAILURE
[ 398.076779] systemd[1]: systemd-suspend.service: Failed with result
'exit-code'.
[ 398.109255] systemd[1]: Failed to start Suspend.
[ 398.118704] systemd[1]: Dependency failed for Suspend.
[ 398.136283] systemd-logind[135]: Operation 'sleep' finished.
[ 398.137770] systemd[1]: suspend.target: Job suspend.target/start
failed with result 'dependency'.
[ 398.139105] systemd[1]: sleep.target: Unit not needed anymore. Stopping.
[ 398.167590] systemd[1]: Stopped target Sleep.
[ 398.201558] systemd-networkd[220]: usb0: Gained carrier
root@iwg26:~# candump can0 | head -n 2
can0 123 [4] DE AD BE EF
can0 123 [4] DE AD BE EF
root@iwg26:~# candump can1 | head -n 2
nothing on can1 anymore :-(
root@iwg26:~# rmmod flexcan
[ 622.884746] systemd-networkd[220]: can1: Lost carrier
[ 623.046766] systemd-networkd[220]: can0: Lost carrier
root@iwg26:~# insmod /mnt/flexcan.ko
[ 628.323981] flexcan 2094000.flexcan: registering netdev failed
and can1 fails to register with:
[ 628.347485] flexcan: probe of 2094000.flexcan failed with error -110
/Sean
