[Intel-gfx] [PATCH] drm/i915: Wait until after wm optimization to drop runtime PM reference

[Maarten Lankhorst]

Op 05-03-16 om 00:59 schreef Matt Roper:
> At the end of an atomic commit, we currently wait for vblanks to
> complete, call put() on the various runtime PM references, and then try
> to optimize our watermarks (on platforms that need two-step watermark
> programming).  This can lead to watermark registers being programmed
> while the power well is powered down.  We need to wait until after
> watermark optimization is complete before dropping our runtime power
> references.
>
> Note that in the future the watermark optimization is probably going to
> move to an asynchronous workqueue task that happens at some arbitrary
> point after vblank.  When we make that change, we'll no longer
> necessarily be operating under the power reference held here, so we'll
> need to wrap the watermark register programmin in a call to
> intel_runtime_pm_get_if_in_use() or similar.
>
> Cc: arun.siluvery at linux.intel.com
> Cc: ville.syrjala at linux.intel.com
> Cc: maarten.lankhorst at linux.intel.com
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94349
> Fixes: ed4a6a7ca853 ("drm/i915: Add two-stage ILK-style watermark programming (v11)")
> Signed-off-by: Matt Roper <matthew.d.roper at intel.com>
post_plane_update can call intel_update_watermarks, will this cause any unintended behavioral changes
if intel_update_watermarks is called before optimize_watermarks?

~Maarten