On Fri, 2024-02-09 at 09:36 +0100, Daniel Drake wrote: > On Thu, Feb 8, 2024 at 5:57 PM David E. Box <david.e.box@xxxxxxxxxxxxxxx> > wrote: > > This does look like a firmware bug. We've had reports of D3cold support > > missing > > when running in non-VMD mode on systems that were designed with VMD for > > Windows. > > These issues have been caught and addressed by OEMs during enabling of Linux > > systems. Does D3cold work in VMD mode? > > On Windows for the VMD=on case, we only tested this on a BIOS with > StorageD3Enable=0. The NVMe device and parent bridge stayed in D0 over > suspend, but that's exactly what the BIOS asked for, so it doesn't > really answer your question. > > On Linux with VMD=on and StorageD3Enable=1, the NVMe storage device > and the VMD parent bridge are staying in D0 over suspend. I don't know > why this is, I would have expected at least D3hot. Yeah something is missing here. When StorageD3Enable is set, the nvme driver prints the following message during boot: "platform quirk: setting simple suspend" If you don't see this, then the driver never saw StorageD3Enable=1. Possible reasons are: - The property doesn't exist - The property isn't set under the ACPI companion device - There is no associated ACPI companion device - The "nvme=noacpi" parameter was passed on the kernel cmdline - The nvme driver was quirked to not use D3 with NVME_QUIRK_FORCE_NO_SIMPLE_SUSPEND. How was the D-state status confirmed? You can use the following to see the D state of PCI devices during suspend in the kernel log: echo -n "file pci-driver.c +p" > /sys/kernel/debug/dynamic_debug/control David > However, given > that the NVMe device has no firmware_node under the VMD=on setup, I > believe there is no way it would enter D3cold because there's no > linkage to an ACPI device, so no available _PS3 or _PR0 or whatever is > the precise definition of D3cold. > > I also realise I may have made a bad assumption in my previous mail > when looking at the Dell device: I was assuming that a parent PCI > bridge cannot go into D3cold if its child devices only got as far as > D3hot, but I now realise I'm not sure if that constraint actually > exists. > > Not sure if these questions are relevant for the consideration of this > patch, but I'll try to find some time to answer them next week. > > Daniel
