[Openchrome-users] HDMI support clarification

[Pascal Ernster]

On Thu, 4 Apr 2013 10:51:17 -0700
Amit Uttamchandani <amit.uttam at gmail.com> wrote:

> Hello,
> 
> I've been following the latest development of HDMI support for
> openchrome. From my understanding HDMI support requires the
> drm-openchrome kernel. However, I just tried plugging in an HDMI
> monitor and I was able to get output, albeit grainy. This is on a
> VX900 chipset with 0.3.1 openchrome driver.
> 
> So is the drm-openchrome kernel required only for accelerated or 1080p
> out? Is there a way to fix this grainy output by passing certain
> options to xorg conf?

At least in my case (VX900 in a Zotac ZBOX VD01), the drm-openchrome
kernel *and* the option "via.modeset=1" (aka "kernel mode setting") was
needed to make 1080p work via HDMI. Some smaller resolutions like 720p,
1400x1050 or 1440x900 also work without the drm-openchrome kernel and
without KMS.

As Xavier pointed out to me, some acceleration features (mainly XV and
many 2D acceleration features) don't work yet with KMS but only with
UMS. He told me however that KMS support for these acceleration
features is a top priority, so the situation might improve quite a bit
in the near future.

For the time being, you basically have to choose between "1080p via
HDMI but modified 3.8RC6 kernel and buggy or nonworking video
acceleration"  and "working video acceleration and (more or less)
arbitrary kernel version, but no 1080p via HDMI".

regards
Pascal