* Grygorii Strashko <grygorii.strashko@xxxxxx> [150826 11:01]:
> Now Kernel fails to boot 50% of times (form build to build) with
> RT-patchset applied due to the following race - on late boot
> stages deferred_probe_work_func races with omap_device_late_ini
>
> late_initcall
> - deferred_probe_initcal() tries to re-probe all pending driver's probe.
> [In general, It's NOT expected to probe any other built-in drivers after
> deferred_probe_initcal() is finished, because most of
> late_initcall_sync/late_initcall functions expected that all driver
> or probed or deferred already.]
>
> - later on, some driver is probing in this case It's could cpsw.c
> (but could be any other drivers)
> cpsw_init
> - platform_driver_register
> - really_probe
> - driver_bound
> - driver_deferred_probe_trigger
> and boot proceed.
> So, at this moment we have deferred_probe_work_func scheduled.
>
> late_initcall_sync
> - omap_device_late_init
> - omap_device_idle
>
> CPU1 CPU2
> - deferred_probe_work_func
> - really_probe
> - omap_hsmmc_probe
> - pm_runtime_get_sync
> late_initcall_sync
> - omap_device_late_init
> if (od->_driver_status != BUS_NOTIFY_BOUND_DRIVER) {
> if (od->_state == OMAP_DEVICE_STATE_ENABLED) {
> - omap_device_idle [ops - IP is disabled, ]
> - [fail]
> - pm_runtime_put_sync
> - omap_hsmmc_runtime_suspend [ooops!]
OK idling of unclaimed devices should not happen for deferred probe,
it should only happen when there's no driver and no probing happening.
> Lets remove just remove omap_device_late_init completely as suggested
> by Tero Kristo:
>
> "How about remove omap_device_late_init call completely. I don't think
> it does anything useful at the moment; none of the omap devices get
> enabled outside runtime_pm, so there should be no need to explicitly
> disable the devices."
I think this is still needed from PM point of view as otherwise we
don't idle any devices that don't have a driver available. Or am I
missing something?
To me it seems the bug is relying on the BUS_NOTIFY_BOUND_DRIVER is
not set in the deferred probe case.
Regards,
Tony
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