[PATCH] [rfc] drm: add some caps for userspace to discover more info for dumb KMS driver

[Alan Cox]

On Thu, 29 Sep 2011 09:43:12 -0700
Eric Anholt <eric at anholt.net> wrote:

> On Thu, 29 Sep 2011 16:26:32 +0100, Dave Airlie <airlied at gmail.com> wrote:
> > From: Dave Airlie <airlied at redhat.com>
> > 
> > For the simple KMS driver case we need some more info about argb cursor
> > limits and a preferred depth and if shadowed framebuffer access is preferred.
> > 
> > I've only added this for intel/radeon which support the dumb ioctls so far.
> > 
> > I really don't want to expose a truck load of info, just enough for X to
> > start without configuration with a hw cursor.
> > 
> > If you need something really fancy you should be writing a real X.org driver.
> 
> Would prefer_shadow ever be 0?

Devices which are fully cache coherent with the CPU are probably a good
example. No point running back buffers then. Also any device with a
generally slow CPU/GPU interface rather than one where write is fast but
read is not.

Alan