about Xvideo support in glamor

[Chris Wilson]

On Tue, Jun 04, 2013 at 04:05:04PM +0800, bradpitt wrote:
>    I want to ask some questions about Xvideo.  
>    1. What is the difference between overlay video and textured video
>    adaptor��

The overlay is a special piece of hardware that allows the scanout to
combine multiple surfaces in its output to the display. That hardware
tends to be more power efficient (and will couple into the display
power management such as PSR far better) and also have better
multi-tap scaling algorithms. However, the overlay is a custom
interface for hardware, what you should be considering to reuse is the
sprite video backend Intel implements which uses drm_plane for a
hardware agnostic method of setting up the secondary planes - however,
even with the sprite interface we still have a few i915 specific calls
that should one day be replaced with plane properties.

The textured video adaptor just uses the GPU to combine the YUV onto the
frontbuffer (or other render target).

Also note that both adaptors can be used in passthrough mode where the
client sends a GEM name rather than a buffer. This will eventually be
superseded by DRI3 - but that has not yet been considered in the current
proposal.

>    2. xf86-video-intel has implemented overlay video adaptor and textured
>    video adaptor. If I want to add Xvideo adaptor in glamor, which should I
>    use? can I implement putvideo function with I965DisplayVideoTextured() and
>    intel_display_overlay() in glamor?

You should start with writing a textured video adaptor as that is the most
useful generic routine. Hooking up glamor to use drm_plane should be
relatively trivial.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre