DRM connector/encoder/crtc framework documentation?

[Matt Sealey]

Hi guys,

Is there any canonical or even rough, old documentation (I noticed a
connector/encoder structure change lately) on how the DRM
crtc/encoder/connector framework is constructed and what the
responsibilities of each component are in a display driver?

The Intel driver is a little overcomplicated to derive from for the
work I have in mind, which is an embedded graphics driver. There is no
setting up i2c buses on weird chips (it's a real i2c bus) and there
would have to be platform_device support on init which is an easy
addition, but without a good non-code description of what goes on
where (in-code comments are not that great), I am not sure I really
understand enough how it is all meant to operate.

What we have is an i.MX515 with a display controller (IPU) which can
do video overlay and all that fancy stuff. This is the CRTC right?
This would be setting up clocks, and managing which GEM object is the
current framebuffer?

Implementing a GEM memory manager to allocate framebuffers and other
objects goes under this, and then the CRTC talks to it's encoder.. but
how does the connector come in? All I see is that it is a sort of
abstraction for parsing EDID data such that you can find out if you're
running HDMI ("TV mode" on a TV) or DVI-like displays ("PC mode" on a
TV).

Does that about sum it up?

Is there a simple skeleton (maybe a virtual or off-screen
framebuffer?) implementing the framework so I can relieve myself of
having to pick apart Intel and Radeon drivers and working out for
myself why and how they differ in implementation?

BTW the other question is: for future-proofing do I use GEM or TTM or what?

-- 
Matt Sealey <matt at genesi-usa.com>
Product Development Analyst, Genesi USA, Inc.