[Mesa-dev] Broadcom VideoCore IV

[Mohamed MEDIOUNI]

Le 21 avr. 2014 13:16, "Rob Clark" <robdclark at gmail.com> a écrit :
>
> On Sat, Apr 19, 2014 at 9:32 AM, Mohamed MEDIOUNI
> <mohamedmediouni91 at gmail.com> wrote:
> > The VideoCore IV GPU has 14 cores:
> >
> > - 2 VPU Cores : Full-blown cores which run the ThreadX RTOS.
> > There is an experimental LLVM port to it and also the VBCC C89
> > compiler(which has'nt time support so classic benchmarks run
indefinitely).
> > The binary blob run on that.
> > 5 GFlops
> >
> > - 12 QPU Cores : 3D cores officially documented by Broadcom and using a
> > tile-mode rendering architecture.
> > The full Android driver for that was open-sourced at the end of
February.
> >
> > 24Gflops
> >
> > Questions:
> >
> > Can Gallium3D run with tile-mode rendering architecture ?
>
> yes, adreno (freedreno) is a tiler
>
> > Is it better using Mesa and  the Broadcom shader compiler ?
>
> Allegedly it may be easier to shoehorn in the blob compiler with a
> mesa/dri driver vs mesa/gallium driver.  That probably shouldn't be
> too much of a concern in the long run.  Overall I think a gallium
> driver would be much easier to implement... gallium plus helpers
> provide a lot to the driver writer.
>
> > Is it better using the VPU and an adapted LLVMpipe ?
>
> I guess you are talking about keeping the driver-on-videocore
> approach?  That may have some advantages when it comes to handling
> security (lack of mmu) on r-pi.  But other than that, I suspect
> everything else will be easier to develop/debug on the arm side.  And
> I suspect avoiding round trips to the coprocessor will help
> performance in a lot of cases.
>
> so if you can figure out a way to deal with security aspect with arm
> side driver, then I'd go for arm side gallium driver as my first
> choice.
>
Have now some problems including :

Need to run the programs as root or chmod 777 /dev/mem and chmod 777
/dev/vc-mem
> BR,
> -R
>
> >
> > _______________________________________________
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> > mesa-dev at lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/mesa-dev
> >
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