Messages in this thread | | | Date | Wed, 22 May 2019 20:53:39 +0200 | From | Lukas Wunner <> | Subject | Re: [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
| |