Suspend/hibernate not working on Dell XPS 15 9500 laptop

Suspend/hibernate not working on Dell XPS 15 9500 laptop

[Trevor Bentley]

I asked on #xen on Freenode and was requested to post here.

Summary: Under Xen, both suspend and hibernate operations put the laptop 
into some sort of unrecoverable low-power mode, and a force power-off is 
required.

Environment:
  - Dell XPS 15 9500, BIOS 1.0.1 (this is a new 2020 model)
  - Intel i7-10750H
  - Intel i915 + Nvidia GTX 1650 Ti Mobile
  - Arch linux (clean install)
  - Linux kernels 5.7.5, 5.7.6 tested
  - i915 driver loaded, no nvidia drivers loaded (nouveau blacklisted)
  - Xen 4.13.1, 4.14.0-rc3 tested
  - UEFI, GRUB2 bootloader, LUKS-encrypted /boot, /root, and swap 
(unencrypted /efi with GRUB stub loader)

My Xen was built from this Arch AUR: https://aur.archlinux.org/packages/xen/
With these small patches to bump to 4.13.1 using gcc 10: 
https://github.com/sl4mmy/docker-aur-xen
And the same patches manually applied to a git checkout to bump to 
4.14.0-rc3.

In non-Xen boots, both suspend and hibernate work (using 's2idle' for 
mem, unsure about 'deep').

In Xen, with no guests configured, both suspend and hibernate in Dom0 
power down the screen, fans, and keyboard backlight.  Once suspended, 
nothing awakens it.

I tried every combination of /sys/power/pm_test 
(freezer/devices/platform with s2idle and 
core/processors/platform/devices/freezer with deep), and all pm tests 
*succeed*.  It goes into whichever low power mode, waits 5 seconds, and 
fully recovers.

I'm unable to interpret the results when /sys/power/pm_trace is enabled. 
  "hash matches" is printed in the dmesg log, seemingly always in a 
different place/format.  /sys/power/pm_trace_dev_match just reported 
"acpi" the few times I checked it.

Please let me know if you have any suggestions to try, or if you need 
any extra information for debugging.

Thanks,

Trevor

Re: Suspend/hibernate not working on Dell XPS 15 9500 laptop

[Jan Beulich]

On 27.06.2020 10:35, Trevor Bentley wrote:
> Please let me know if you have any suggestions to try, or if you need 
> any extra information for debugging.

I don't suppose you have a serial port on this laptop? I ask because
the serial log (and the possibility to issue debug keys) are about
the only thing debugging-wise that may help here, short of someone
noticing the underlying problem by code inspection.

Do you have any indication of the laptop at least partly waking up
again, e.g. from some LED or other indicator activity?

Jan

Re: Suspend/hibernate not working on Dell XPS 15 9500 laptop

[Roger Pau Monné]

On Sat, Jun 27, 2020 at 08:35:27AM +0000, Trevor Bentley wrote:
> I asked on #xen on Freenode and was requested to post here.
> 
> Summary: Under Xen, both suspend and hibernate operations put the laptop
> into some sort of unrecoverable low-power mode, and a force power-off is
> required.
> 
> Environment:
>  - Dell XPS 15 9500, BIOS 1.0.1 (this is a new 2020 model)
>  - Intel i7-10750H
>  - Intel i915 + Nvidia GTX 1650 Ti Mobile
>  - Arch linux (clean install)
>  - Linux kernels 5.7.5, 5.7.6 tested
>  - i915 driver loaded, no nvidia drivers loaded (nouveau blacklisted)
>  - Xen 4.13.1, 4.14.0-rc3 tested
>  - UEFI, GRUB2 bootloader, LUKS-encrypted /boot, /root, and swap
> (unencrypted /efi with GRUB stub loader)

Completely a shot in the dark, but have you tried with legacy boot
(BIOS) instead of UEFI? To try to rule out what might cause the
issues.

Roger.

Re: Suspend/hibernate not working on Dell XPS 15 9500 laptop

[Trevor Bentley]

> I don't suppose you have a serial port on this laptop? I ask because
> the serial log (and the possibility to issue debug keys) are about
> the only thing debugging-wise that may help here, short of someone
> noticing the underlying problem by code inspection.

Afraid not, it's hyper-modern; just 3 USB-C ports.

It looks like identical hardware in the Dell Precision 5550 model, in 
case anybody gets access to either and wants to test.

> Do you have any indication of the laptop at least partly waking up
> again, e.g. from some LED or other indicator activity?

None at all, no.  Could be missing the keyboard events entirely, or 
getting them and failing to wake.  I've tried built-in keyboard, 
external keyboard, and closing/opening the lid.

When using the /sys/power/pm_test commands, does that actually do 
anything in a Xen environment, or is that being consumed by dom0 and not 
triggering the real VMM low-power paths?  Is there any similar debug 
mechanism for the hypervisor?

Let me know if there is any useful information I can extract.  I'm happy 
to build patched kernels if it will help.

Thanks,

-Trevor

Re: Suspend/hibernate not working on Dell XPS 15 9500 laptop

[Trevor Bentley]

> Completely a shot in the dark, but have you tried with legacy boot
> (BIOS) instead of UEFI? To try to rule out what might cause the
> issues.

 From the BIOS: "Legacy Boot mode is not supported on this platform."

This is my punishment for buying a brand new laptop model for Linux...

-Trevor