Re: bisected regression, v3.5 -> next-20120724: PCI PM causes USB hotplug failure

[Bjørn Mork <bjorn@xxxxxxx>]

"Rafael J. Wysocki" <rjw@xxxxxxx> writes:

> This is not really necessary.  The problem is the change of behavior I was
> worried about some time ago.
>
> Namely, the device in question apparently doesn't support ACPI D3_hot,
> so acpi_pm_device_sleep_state() returns D2 as the target state, where it
> would return D3(cold) before the commit in question.
>
> To fix the regression, we'd need to reverse the current initial value of
> the d3cold_allowed flag so that it is set to "true" by default and only
> set to "false" for devices where we suspect there may be problems with
> D3_cold (like PCI Express ports).

Good.  May I also request a few lines describing d3cold_allowed in e.g
Documentation/ABI/testing/sysfs-bus-pci?  I must admit that I thought
that was the policy for any new sysfs file, but it seems that is only
in the USB subsystem?

Anyway, I believe it ought to be a requirement.  If we are meant to
tweak some knob, then we must known how and when to do so.  If not, then
why add it in the first place?


Bjørn
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