[cairo] [PATCH 00/36] DRM backend fixes / take 2

Enrico Weigelt, metux IT consult enrico.weigelt at gr13.net
Mon Dec 14 03:28:44 PST 2015

On 13.12.2015 15:22, Chris Wilson wrote:

Hi folks,

> Yes, the drm backend bitrotted. If you want to play with it, by all
> means, we will take whatever patches you have to make it work again
> (iirc i965 was never completed, at least not as far as i915).

By the way: did it ever work w/ plain DRM/KMS framebuffer ?
(w/o any GPU acceleration)

> I would keep that set of patches into 2 groups core/non-drm and drm. 

I've already sorted them that way.

Maybe you've already seen that my core patches introduce some helper
macros, which aren't used outside my DRM patches yet. I'd suggest a
deeper discussion about generic helpers, eg. for conversion between
boxes and rects, etc. ... in a later stage, we could add some more
optimizations there (eg. use vector ops, etc)

> The core patches will need careful review in case they have side-effects
> for other backends,

Of course. Therefore I'd appreciate if some more people could have a
closer look and give signed-off for those which seem fine.

Is anybody here willing to maintain a separate incubator branch for that
or should I keep it on my side ?

> but as the drm backend is experiemental self-contained
> patches to it I feel comformtable with just merging.

I'd like to get some more feedback, as my understanding of the whole
architecture is still pretty low.

> The biggest change in cairo since cairo-drm, as you have probably
> observed, was the restructing of the compositor architecture. I would
> suggest restructing cairo-drm on top of that pipeline would be a good
> place to begin. As always, just creating a base layer that can open a
> dumb GEM buffer (i.e. common for DRM drivers), render to it and pass it
> around between libraries/applications is the first step. Maybe look at
> GBM for that piece of middleware. Adding acceleration is where the fun
> is though :)

Well, I dont really know where to start w/ that yet. Unfortunately,
that change was really huge, so it's hard to understand, what's really
going on here. Some documentation would be very helpful.

(by the way: that's the reason why I try to keep my patches on a
fine granularity)


Enrico Weigelt,
metux IT consulting

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