Re: GSoC Raspberry Pi Graphics project

[Robert Swindells <rjs%fdy2.co.uk@localhost>]

Brian Schnepp <stebor2jr%gmail.com@localhost> wrote:
>I've just recently submitted my proposal for implementing this project
>for this year's Google Summer of Code. My proposal specifically
>suggests reimplementing the Linux vc4 driver for the NetBSD kernel, so
>it uses the same DRM interfaces as the existing nouveau and amdgpu
>ports, but without sharing any actual code from the vc4 driver which
>is under the GPL license. Ideally, this should be seen as compatible
>under Mesa, so existing GLES programs should be able to use it. In
>addition to this, some DeviceTree code for the Pi needs to be added.

Writing a DRM driver from scratch seems too much work for a Summer of
Code project to me.

>I'd be very happy to write a GPU driver, but out of curiosity, I would
>like to know if there might be a different way to implement this that
>I just haven't seen yet, like if there was a way to shim the driver to
>userspace and keep the original GPLed vc4 driver out of the kernel
>that way, and just have it sent signals or something like that, or if
>there is some other way to do this as well. I'd also like suggestions
>on this project in general, and would like to make sure this method of
>supporting the VC4 GPU sounds good overall.

I think the way we were expecting to get around the GPL code for some
GPUs was to build the driver into a module that is loaded at runtime.

We also want to do this for the Lima and Panfrost drivers which will
need similar extensions to the emulated Linux kernel functions to
call into the device tree as would be needed by the VC4 driver.

I am part way through doing this for the Lima driver.

Robert Swindells