Re: CONFIG_PCIEASPM needed for ASPM?

[Shaohua Li]

On Fri, Oct 24, 2008 at 09:40:27AM +0800, Luis R. Rodriguez wrote:
> I know, the question is silly right? I thought so too, but I started
> reviewing the code and noticed most of it is just setting up values in
> data structures for the kernel's awareness of capabilities, it also
> updates the state in case of BIOS foobar, and there is also clock
> retraining if possible to reduce latency. Is that it? Did I miss
> something or is it really possible for devices to be able to use
> L0s|L1 or L1 by just having a BIOS which does things correctly?
> 
> That is can our devices be using ASPM without any OS interaction,
> without CONFIG_PCIEASPM enabled?
you didn't miss anything. If BIOS enables ASPM, even OS doesn't do anything,
ASPM will be used. ASPM enter/leave is controlled by hardware, OS just
enables the capability.

Thanks,
Shaohua
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