[Intel-gfx] [PATCH 1/2] drm/i915: re-enable semaphores by default

[Daniel Vetter]

On Mon, Nov 14, 2011 at 21:39, Eugeni Dodonov <eugeni.dodonov at intel.com> wrote:
> Semaphores seem to fix most of the hangs on SNB and IVB, and do not cause
> any known regressions as of now.
>
> Let's re-enable them by default to provide a wider testing and coverage.
>
> Acked-by: Keith Packard <keithp at keithp.com>
> CC: Jesse Barnes <jbarnes at virtuousgeek.org>
> CC: Daniel Vetter <daniel.vetter at ffwll.ch>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=42696
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=40564
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=41353
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=38862
> Signed-off-by: Eugeni Dodonov <eugeni.dodonov at intel.com>

Semaphores are still broken on my snb in combination with DMAR. ppgtt
seems to slightly change the failure mode and probably helps in
tracking this down, but without ppgtt it's a hard hang a few seconds
after login. So we need to check whether DMAR is enabled (on the
entire system, i.e. the variable exported for the ilk workaround is
not good enough) on snb and then disable it by default. So in this
current form:
Nacked-by: Daniel Vetter <daniel.vetter at ffwll.ch> (still causes easily
reproducible hard-hangs)

I don't have anything against enabling this by default on ivb.
-- 
Daniel Vetter
daniel.vetter at ffwll.ch - +41 (0) 79 365 57 48 - http://blog.ffwll.ch