Testing drm-i915-update-38 (c6d9af5) with patched i915_gem.c, encouraging results.

[Arto Pekkanen]

For some reason I was not able to attach the diff to the previous 
message, so I will try to attach it here.

Arto Pekkanen kirjoitti 08.02.2016 05:09:
> Hi again.
> 
> I realized that previously the  drm-i915-update-38 (c6d9af5) kernel
> crashed because of a BUG_ON trap in i915_gem.c, not because of actual
> code fault.
> 
> Then I found the following discussion in GitHub:
> https://github.com/freebsd/freebsd-base-graphics/issues/2
> 
> There the user myfreeweb "McGyver'd" the BUG_ON trap away by replacing
> it with WARN_ON -macro. I wanted to see if the driver would work, so I
> did the same.
> 
> Attached is the diff that replaces BUG_ON with WARN_ON in i915_gem.c
> and thus makes the kernel not crash while playing games/openarena.
> 
> The results:
> - kernel boots
> - vt console works
> - LVDS + 2 monitors on HDMI2 and HDMI3, all work with native 
> resolutions,
>   NOTE: this is an IMPROVEMENT! Previously X.org would HANG if I
> enabled more than 2 monitors!
> - video playback is perfect, no tearing, minimal CPU use, tested with
>   - www/chromium
>   - multimedia/mpv (with VAAPI enabled in multimedia/mpv and 
> multimedia/ffmpeg)
> - games/openarena works just fine
> 
> In fact, I can actually run games/openarena at the same time with
> www/chromium wathing https://www.youtube.com/watch?v=5xkNy9gfKOg (full
> HD tearing test video), with some stuttering on both ... but this is
> to be expected, because the kernel has to serve 2 OpenGL pipes at the
> same time which is problematic.
> 
> And because I can now use 3 outputs at the same time, I am very 
> impressed.
> 
> I see many warnings like this in dmesg:
> Feb  8 04:33:15 leno kernel: error:
> [drm:pid1073:i915_gem_object_move_to_inactive] *ERROR* WARN ON:
> obj->base.write_domain & ~I915_GEM_GPU_DOMAINS
> 
> The frequency between these errors is about one second when I run
> games/openarena. With www/chromium I do not see these warnings.
> 
> The only real gripe I have is that the FreeBSD 11 -based kernel does
> not detect my Intel Wifi chip, yet stock FreeBSD 10.2 was able to do
> that. Should I report this as a regression somewhere? The problem with
> reporting this is that I am running FreeBSD 10.2 userland, and I feel
> like the developers might not want to deal with that.
> 
> I will leave the laptop on while I sleep, leave it running the Tearing
> Test -video mentioned above. If it crashes I will post core dump etc.

-- 
Arto Pekkanen