[Intel-gfx] REGRESSION with 5.12: Suspend not working on Toshiba notebook

[Joonas Lahtinen]

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Quoting Zhenyu Wang (2021-04-30 02:58:28)
> On 2021.04.29 20:14:50 +0200, Andreas Friedrich wrote:
> > Hello Joonas,
> > 
> > with kernel 5.12 suspend to memory is no longer working on my old
> > Toshiba Tecra A10 notebook.
> > 
> > After calling /sbin/pm-suspend the screen is dimmed but the CPU fan is
> > still running, the system is frozen and is not in suspended state. The
> > only way to get the system working again is to hard power off and on.
> > 
> > Kernel 5.11.16 works well.
> > 
> > Bisecting the kernel leads me to your commit, which caused the problem:
> > 
> >   commit c071a6c0fef0fade787d827c7fc0e07481512326 (HEAD, refs/bisect/bad)
> >   Merge: a2dd2ff50cde 02dd2b12a685
> >   Author: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> >   Date:   Thu Jan 21 15:10:16 2021 +0200
> > 
> >     Merge tag 'gvt-gt-next-2021-01-18' of https://github.com/intel/gvt-linux into drm-intel-gt-next
> > 
> >     gvt-gt-next-2021-01-18
> > 
> >     - GVT cmd parser enhancement against guest context (Yan)
> > 
> >     Signed-off-by: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> >     From: Zhenyu Wang <zhenyuw at linux.intel.com>
> >     Link: https://patchwork.freedesktop.org/patch/msgid/20210118050739.GY15982@zhen-hp.sh.intel.com

That is a merge commit, it doesn't itself change anything as there were no
conflicts. It just indicates that two trees got merged.

Bisecting should end up in a commit that has code changes. Then you should
be able to try to revert the offending commit from the latest mainline kernel.
Most of the time that can be used to confirm that reverting specific commit
fixes issue (unless the commit has a lot of dependencies). This is not
required though, if you are able to bisect to a single code change commit
that'll allow us to provide fix to try.

If you are able to provide a bisect to a one patch, please do report it
as a bug, let's then take it from there.

See:

https://01.org/linuxgraphics/documentation/how-report-bugs

> > Not every suspend results in a frozen system, so I think a race
> > condition is on the way.

This would further tip the scale towards the bisect being a false
positive. I know it can be painful to do dozens of runs per each
bisecting point, but it's really needed to arrive at the right patch.

What kind of rate you have for hitting the issue on 5.12 kernel?

> > Appendix:
> > - Kernel configuration "5.12.config.gz"
> > - My grub kernel boot parameters:
> >   root=/dev/sda5 snd-hda-intel.model=toshiba resume=/dev/sda3 printk.time=1
> > 
> > Please let me know if I could help to fix the problem.
> > 
> 
> Looks gvt is not enabled in config or runtime, so can't think that gvt merge should be related...

Yes, I think the merge commit is a red herring.

Regards, Joonas