[Lima] [PATCH 0/2] Lima DRM driver

[Alyssa Rosenzweig]

> > Another one: What's the plan with extending this to panfrost? Or are the
> > architectures for command submission totally different, and we'll need
> > separate kernel drivers for utgard/midgard/bifrost?
> + Alyssa & Rob
> There is a gitlab issue about sharing kernel driver:
> https://gitlab.freedesktop.org/panfrost/linux/issues/1
> 
> But seems utgard (discrete shader arch) really differs with midgard/bifrost
> (unified shader arch), so that ARM also have different official kernel drivers.

We're operating off that Utgard and Midgard/Bifrost are two completely
separate architectures. They share a name, but not much else in
practice. Separate shaders vs unified shaders is one distinction;
command streams vs state descriptors is another huge one (as far as
userspace is concerned); etc. As Qiang pointed out, Arm has two (kernel)
drivers, one for Utgard, one for Midgard.

Beyond a few isolated routines (e.g. texture tiling), IMO sharing between
lima and panfrost makes about as much sense as sharing between lima and
etnaviv/vc4/freedreno. Yeah, there are similarities, but that's what
common code is for, not for forcing code cohabitation.

-Alyssa