On Tue, Jan 8, 2019 at 10:35 AM Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> wrote: > > On Mon, Jan 07, 2019 at 02:13:14PM +0100, Rafael J. Wysocki wrote: > > On Mon, Jan 7, 2019 at 2:01 PM Mika Westerberg > > <mika.westerberg@xxxxxxxxxxxxxxx> wrote: > > > > > > Gigabyte X299 DESIGNARE EX motherboard has one PCIe root port that is > > > connected to Alpine Ridge Thunderbolt controller. This port has slot > > > implemented bit set in the config space but other than that it is not > > > hotplug capable in the sense we are expecting in Linux (it has > > > dev->is_hotplug_bridge set to 0): > > > > > > 00:1c.4 PCI bridge: Intel Corporation 200 Series PCH PCI Express Root Port #5 > > > Bus: primary=00, secondary=05, subordinate=46, sec-latency=0 > > > Memory behind bridge: 78000000-8fffffff [size=384M] > > > Prefetchable memory behind bridge: 00003800f8000000-00003800ffffffff [size=128M] > > > ... > > > Capabilities: [40] Express (v2) Root Port (Slot+), MSI 00 > > > ... > > > SltCap: AttnBtn- PwrCtrl- MRL- AttnInd- PwrInd- HotPlug- Surprise- > > > Slot #8, PowerLimit 25.000W; Interlock- NoCompl+ > > > SltCtl: Enable: AttnBtn- PwrFlt- MRL- PresDet- CmdCplt- HPIrq- LinkChg- > > > Control: AttnInd Unknown, PwrInd Unknown, Power- Interlock- > > > SltSta: Status: AttnBtn- PowerFlt- MRL- CmdCplt- PresDet- Interlock- > > > Changed: MRL- PresDet+ LinkState+ > > > > > > This system is using ACPI based hotplug to notify the OS that it needs > > > to rescan the PCI bus (ACPI hotplug). > > > > > > If there is nothing connected to any of the Thunderbolt ports the root > > > port will not have any runtime PM active children and is thus > > > automatically runtime suspended pretty soon after boot by PCI PM core. > > > Now, when a device is connected the BIOS SMI handler responsible for > > > enumerating newly added devices is not able to find anything because the > > > port is in D3. > > > > > > For this reason we block power management of PCIe root and downstream > > > ports that have slot implemented set and have node in ACPI namespace. > > > > > > Link: https://bugzilla.kernel.org/show_bug.cgi?id=202031 > > > Reported-by: Kedar A Dongre <kedar.a.dongre@xxxxxxxxx> > > > Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> > > > > Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> > > Thanks! > > However, I'm having second toughts about this because I remembered that > people put a lot of effort getting discrete graphics with power resource > attached to the root port powering off properly. If the root port > matches the criteria in this patch it will not be able to go into D3 > anymore. It might affect others such as M.2 connected NVMe or WiFi chip > as well. For that reason I would still prefer blacklist, at least for now. Blacklist would be fine by me too.
