[RFC 4/4] drm: Add NVIDIA Tegra support

[Alex Deucher]

On Thu, Apr 12, 2012 at 5:33 AM, Thierry Reding
<thierry.reding at avionic-design.de> wrote:
> * Sascha Hauer wrote:
>> You might want to have a look at the sdrm patches I recently posted to
>> dri-devel and arm Linux Kernel. Among other things they allow to
>> register crtcs/connectors/encoders seperately so that each of them can
>> have its own representation in the devicetree. I haven't looked into
>> devicetree support for DRM, but with or without devicetree the problem
>> that we do not have a single PCI card for registering all DRM components
>> is the same.
>
> I'll do that. One interesting use-case that's been on my mind for some time
> is if it would be possible to provide a CRTC via DRM that isn't part of the
> SoC or DRM "device" but which can display a framebuffer prepared by the DRM
> framework.
>
> In other words I would like to use the Tegra hardware to render content into
> a framebuffer (using potentially the 3D engine or HW accelerated video
> decoding blocks) but display that framebuffer with a CRTC registered by a
> different driver (perhaps provided by a PCIe or USB device).
>
> I think such a setup would be possible if the CRTC registration can be
> decoupled from the DRM driver. Perhaps sdrm even supports that already?

You should be able to do something like that already with dma_buf and
the drm prime infrastructure.  There's even a drm driver for the udl
USB framebuffer devices.

Alex