Re: [PATCH v2 04/10] PCI/P2PDMA: Clear ACS P2P flags for all devices behind switches

[Logan Gunthorpe]

On 01/03/18 04:15 PM, Bjorn Helgaas wrote:
> The question is what the relevant switch is.  We call pci_enable_acs()
> on every PCI device, including Root Ports.  It looks like this relies
> on get_upstream_bridge_port() to filter out some things.  I don't
> think get_upstream_bridge_port() is doing the right thing, so we need
> to sort that out first, I guess.

Yes, well if a port has an upstream bridge port and that port has an 
upstream bridge port we are almost certainly looking at a port in a 
switch. If you have a better suggestion to only disable ACS bits on 
downstream switch ports I'd be happy to consider it.


> This might be a good start, but whatever the implications are, they
> need to be distilled and made clear directly in the changelog and the
> Kconfig help text.

Well, I tried. I'll expand on it for v3.

Logan