[Intel-gfx] [PATCH v2 1/4] drm/i915: add warning for unidle GPU

[Daniel Vetter]

On Sat, Sep 24, 2011 at 03:23:04PM -0700, Ben Widawsky wrote:
> When we attempt to idle the GPU we take a shortcut by checking if our
> lists are empty and if so, avoid doing a synchronizing flush. The
> warning will let us know if this assumption turns out to not be correct.
> 
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Signed-off-by: Ben Widawsky <ben at bwidawsk.net>

I've just discussed this quickly with Chris on irc and it's probabbly
best to just kill the list_empty early bailout. gpu_idle isn't a fastpath,
so who cares. One candidate where we emit commands to the ring without
adding anything onto these lists is e.g. pageflip. There're probably
more.

Also it looks like this causes us to no properly idle the gpu on
suspend/resume. Might fix issues especially on gen2/3 where we put an
MI_WAIT in front of the flip, hence enlarging the window to up to 20 ms.
-Daniel
-- 
Daniel Vetter
Mail: daniel at ffwll.ch
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