Re: Accelerated frame buffer functions

James Simmons
2005-02-02T19:40:01Z

> > You should look at writing a DRM driver. DRM implements the kernel
> > interface to get 3D hardware running. It is a fully accelerated driver
> > interface. They are located in drivers/char/drm
>
> Have the standard frame buffer drivers been abandoned, even
> for devices that have no 3D acceleration (like the Geode GX2)?

No. It is still around.

> I took a quick look at the DRM stuff, and it looked like extreme
> overkill for what I need, if it even can be used for what I want
> to do. At first glance it looked like this is only relevant for
> OpenGL/X11 3D-stuff, which I have absolutely no use for.

This is usually the case for embedded chips. This is the reason the fbdev
userland interface is still around.

> GX2 is an integrated CPU/graphics chip for embedded systems.
> We have third party applications that use the framebuffer device,
> and I was hoping to make things faster by writing an accelerated
> driver. The only thing I need answered is how to access fb_ops
> from userspace.

You can mmap the mmio address space and program the registers yourself.
A bonus is the example code is in the driver :-)

> If that is impossible because all the framebuffer
> code is leftover junk that no one uses anymore, or even /can/
> use anymore because the userspace interface is gone, please let
> me know now so I don't have to waste any more time.

The userspace interface is still there.