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SubjectRe: [PATCH] PCI / PM: Don't runtime suspend when device only supports wakeup from D0
On Wed, May 22, 2019 at 02:39:56PM -0400, Alan Stern wrote:
> According to Kai, PME signalling doesn't work in D0 -- or at least, it
> is _documented_ not to work in D0 -- even though it is enabled and the
> device claims to support it.
>
> In any case, I don't really see any point in "runtime suspending" a
> device while leaving it in D0. We might as well just leave it alone.

There may be devices whose drivers are able to reduce power consumption
through some device-specific means when runtime suspending, even though
the device remains in PCI_D0. The patch would cause a power regression
for those.

In particular, pci_target_state() returns PCI_D0 if the device lacks the
PM capability.

Thanks,

Lukas

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