[Intel-gfx] [PATCH 30/35] drm/i915: Replace the ILK/SNB/IVB/HSW watermark code

[Ville Syrjälä]

On Fri, Jul 05, 2013 at 02:51:36PM -0300, Paulo Zanoni wrote:
> 2013/7/5  <ville.syrjala at linux.intel.com>:
> > From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> >
> > There is a major problem with the watermark registers; they're not
> > double buffered. So we need to make sure we update them at the correct
> > time when messing about with planes. The correct time is the beginning
> > of vblank.
> >
> > So when we determine that the watermarks need to updated hand in hand
> > with the next vblank, we store the pre-computed watermarks under
> > intel_crtc, and when the vblank happens, we promote the pending
> > watermarks to active status.
> >
> > on HSW when the watermarks for any pipe change, we must merge the
> > watermarks from all pipes so that we can determine the correct LP1+
> > watermark levels. For simplicity we follow the same codepaths for
> > pre-HSW hardware as well, but there all the LP1+ watermarks will be
> > disabled when multiple pipes are enabled. Once the watermarks are
> > merged we check them for validity, disabling any invalid levels.
> >
> > Touching the watermark registers causes the hardware to re-evaluate the
> > watermarks, which expeds some power. So after merging the watermarks
> > we check which watermark registers actually need to be changed. And
> > finally we write the watermarks registers in the correct order.
> 
> This patch is way too big for us, poor reviewers. Can you split this
> into many many many tiny patches? I see *a lot* of different changes
> here.

Well, it's one change "rip out the old, bring in the new", or is that
two changes? :P

One problem with more splitting is that the intermediate steps might
not end up making much sense at some point if it's just churning code
around, or adding new bits that do nothing until the full system
is in place.

But I did actaully want to split it up a bit more at least. But I ran
out of time, so it will need to wait until I get back from vacation.

-- 
Ville Syrjälä
Intel OTC