Hi Tony,
On 08/26/2015 09:10 PM, Tony Lindgren wrote:
> * 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.
>
What do you think about below alternative?
diff --git a/arch/arm/mach-omap2/omap_device.c b/arch/arm/mach-omap2/omap_device.c
index 4cb8fd9..72ebc4c 100644
--- a/arch/arm/mach-omap2/omap_device.c
+++ b/arch/arm/mach-omap2/omap_device.c
@@ -901,7 +901,8 @@ static int __init omap_device_late_idle(struct device *dev, void *data)
if (od->hwmods[i]->flags & HWMOD_INIT_NO_IDLE)
return 0;
- if (od->_driver_status != BUS_NOTIFY_BOUND_DRIVER) {
+ if (od->_driver_status != BUS_NOTIFY_BOUND_DRIVER &&
+ od->_driver_status != BUS_NOTIFY_BIND_DRIVER) {
if (od->_state == OMAP_DEVICE_STATE_ENABLED) {
dev_warn(dev, "%s: enabled but no driver. Idling\n",
__func__);
--
regards,
-grygorii
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