Re: [GIT PULL] PCI fixes for v4.10

From: Lukas Wunner
Date: Tue May 02 2017 - 06:48:59 EST

On Mon, May 01, 2017 at 10:41:20PM -0400, Sinan Kaya wrote:
> On 5/1/2017 9:54 PM, Lukas Wunner wrote:
> > (b) ASPM L1 enabled on boot, but disabled after powering off and back on
> > => I believe Sinan is working on this (+cc).
> The decision was made not to touch ASPM registers following hotplug insertion
> unless pcie_aspm.policy=powersave is specified.
> The discussion is here:
> This was done to maintain existing behavior and not break things.

Thanks for the reference, I hadn't followed the discussion in April
very closely, but I think the outcome of the discussion is unfortunate.

As can be seen in Ashok's tests, merely turning slot power off and back
on is sufficient to end up with a setting that draws more power. That
may be equally surprising for users as the issues would be that we seek
to avoid with a "safety-first" ASPM policy. In any case it seems

I hope this is not the end if it and would like to encourage you to
keep working on this. Perhaps it is too simple to just define a
default policy, and what is really needed is a policy that adjusts
itself dynamically to specific devices or workloads, or that can be
influenced by device drivers.

Thanks for your efforts,