Re: [PATCH 14/15] drm/i915: Track frontbuffer invalidation/flushing

From: Daniel Vetter <daniel@ffwll.ch>
To: Chris Wilson <chris@chris-wilson.co.uk>,
	Daniel Vetter <daniel.vetter@ffwll.ch>,
	Intel Graphics Development <intel-gfx@lists.freedesktop.org>,
	Rodrigo Vivi <rodrigo.vivi@intel.com>
Subject: Re: [PATCH 14/15] drm/i915: Track frontbuffer invalidation/flushing
Date: Tue, 17 Jun 2014 09:45:00 +0200	[thread overview]
Message-ID: <20140617074500.GX5821@phenom.ffwll.local> (raw)
In-Reply-To: <20140617065438.GG17744@nuc-i3427.alporthouse.com>

On Tue, Jun 17, 2014 at 07:54:38AM +0100, Chris Wilson wrote:
> On Mon, Jun 16, 2014 at 07:51:34PM +0200, Daniel Vetter wrote:
> > +/**
> > + * intel_frontbuffer_flush - flush frontbuffer
> > + * @dev: DRM device
> > + * @frontbuffer_bits: frontbuffer plane tracking bits
> > + *
> > + * This function gets called every time rendering on the given planes has
> > + * completed and frontbuffer caching can be started again. Flushes will get
> > + * delayed if they're blocked by some oustanding asynchronous rendering.
> > + *
> > + * Can be called without any locks held.
> > + */
> > +void intel_frontbuffer_flush(struct drm_device *dev,
> > +			     unsigned frontbuffer_bits)
> 
> intel_fb_complete.

My naming convetion was:
- intel_frontbuffer: Deals in raw frontbuffer tracking bits.
- intel_fb: Takes a gem object, assumes dev->struct_mutex is held. I've
  stolen these from the intel_mark_fb_busy function.

The main functions are flush/invalidate, all the others just add a bit of
magic (which delays) around them. Imo invalidate is definitely the right
pick if you look at fbc/psr as fancy caches, not sure about flush. Maybe
finish given our sw_finish ioctl, but not sure that's better than flush.
My thinking is:

- invalidate the cache fully (i.e. disable it)
- flush data into the cache again (i.e. enable it again)

Cheers, Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch