Re: Thinkpad T61 display won't wake from hibernate

On 30 November 2022 10:21:13 pm AEDT, Polytropon <freebsd@edvax.de> wrote:

 > On Wed, 30 Nov 2022 06:52:07 +0100, Daniel Tameling wrote:
 > > I can't really help you because I never had to debug suspend/resume
 > > issues, but are you aware of https://wiki.freebsd.org/SuspendResume

That's a good resource to start with.

 > > The list https://wiki.freebsd.org/Laptops contains one T61 and says
 > > Suspend / Resume is working, but it has some notes about things
 > that
 > > interfer with it (https://wiki.freebsd.org/Laptops/Thinkpad_T61).

Further down there's also a Thinkpad_X61s, basically the same hardware series in 12" form, same  as the later T4xx vs X2xx models, the 4 for 14", 2 for 12" and 5xx for 15".

https://en.m.wikipedia.org/wiki/List_of_Intel_graphics_processing_units

https://wiki.freebsd.org/Graphics

https://wiki.freebsd.org/Graphics/Intel-GPU-Matrix

All have some clues, but indicate a good deal of confusion especially over time.  At one time there were drm-kmod, drm-next-kmod, drm-devel-kmod and drm-legacy-kmod, but such terms
become meaningless outside of their timeframe, and I'm yet to find any comprehensive, up to date docs that cover old through to latest systems, especially regarding suspend/resume. </rant>

 > Also note that some BIOSes have a setting that is
 > something like "Repost video on S3 resume", you
 > could check for that, too.

Also sysctl hw.acpi.reset_video, 'Call the VESA reset BIOS vector on the resume path', which may apply to some laptops as old as the T61.

Bottom line with 13.1 and its present drm-kmod is that without the exactly right i915kms.ko, successful resume may remain elusive. 

Happy hunting to all,

cheers, Ian