From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Return-Path: Date: Mon, 26 Feb 2018 14:05:34 +0200 From: Mika Westerberg To: Lukas Wunner Cc: Bjorn Helgaas , "Rafael J. Wysocki" , Linux PCI , Valdis Kletnieks , Mathias Nyman , Linux PM , "Rafael J. Wysocki" , Linux Kernel Mailing List , Peter Wu , Qipeng Zha , Greg Kroah-Hartman , Andreas Noever , Dave Airlie , Qi Zheng Subject: Re: [PATCH v1 2/2] PCI: Allow user to request power management of conventional and hotplug bridges Message-ID: <20180226120534.GO27191@lahna.fi.intel.com> References: <151908155159.37696.9710083237704994886.stgit@bhelgaas-glaptop.roam.corp.google.com> <151908204614.37696.12828004282495415825.stgit@bhelgaas-glaptop.roam.corp.google.com> <20180220181554.GA32228@bhelgaas-glaptop.roam.corp.google.com> <20180222131834.GA5527@wunner.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20180222131834.GA5527@wunner.de> List-ID: On Thu, Feb 22, 2018 at 02:18:34PM +0100, Lukas Wunner wrote: > We do need runtime PM on hotplug ports to power off Thunderbolt > controllers when nothing is plugged in. That saves 1.5 W, so a > noticeable amount of power. I was going to respin the series one > of these days, I think the best I can do is continue to forbid > runtime PM on hotplug ports by default, but whitelist it for > Thunderbolt and allow manually enabling it on other platforms via > the command line. That way, vendors are put in a position to > validate their platforms for runtime PM of hotplug ports, and > perhaps someday we can enable it for all platforms by default, > but with a BIOS cut-off date. AFAIK Windows started to enable runtime PM (RTD3) for native PCIe hotplug ports with the latest release (I guess it's the RS3 release) but only when there is a special ACPI _DSD property ("HotPlugSupportInD3") associated with the root port. I think we can take advantage of that in Linux as well and I already have a patch series to enable runtime PM for such ports but I haven't been able to test it properly yet.