[directfb-dev] Re: Getting started with DirectFB development

[Ville Syrjälä <syrjala@sci.fi>]

On Thu, Nov 20, 2003 at 08:08:02PM +0100, Andreas Korth wrote:
> On my Millenium G550 there is no TV-Out connector but one analog VGA and
> a DVI connector.

Only some G200 cards had TV-out connectors on the card. G400 and newer
cards use the TV-out adapter which must be connected to the number 2
connector. That's the HD15 connector on a single-DVI G550.

> Does this TV-Out limitation also apply to a second
> attached monitor? Or can I use arbitrary resolutions on CRTC1 and CRTC2?

The limitation is specific to DirectFB's TV-out code. The used resolutions
are the standard ITU-R BT656 resolutions. CRTC2 has a special ITU-R BT656
mode which is the only way to get YUV modes and there is no (known) way to
use this mode with a monitor.

If you use a second monitor G450 and G550 cards can use almost any
resolution since the second RAMDAC is 230MHz. I think the first RAMDAC
goes up to 360 MHZ. On G400 the first RAMDAC is 350 or 300 MHz and the
second RAMDAC is limited to 135MHz so it can't provide high reolution
modes.

However DirectFB doesn't support multi-head operation at this time so you
can't use two monitors with DirectFB.

> > In reality you can change the CRTC -> output connector 
> > mapping but we use CRTC2 in a way that only works with TV-out.
> 
> Could you get more specific on this? Especially how the DFB display
> layers are represented in hardware. 

The display layers correspond to hardware components the can read the
video RAM and send it to some output path. You have what Matrox calls
CRTCs ie. cathode ray tube controllers even though they are used even when
the display device isn't a CRT. And then you have BES and CRTC2
sub-picture which are overlays and are mixed to the CRTC outputs in
hardware. BES to CRTC1 output and CRTC2 sub-picture to CRTC2 output.

The data is then sent to zero or more outputs. On G450/G550 you have DAC1
and DAC2 and flat panel outputs. TV-encoder is tied to DAC2 so you can't
use DAC2 and TV-out at the same time and only CRTC2 can output to the
TV-encoder.

I don't know how dual-DVI cards work and a quick look at matroxfb sources
didn't reveal this either. Maybe they use a single CRTC only and the
output is divided into two by the flat panel output.

On G400 you basically have two outputs from the chip. DAC and video-out
bus. On the video-out bus you have the maven chip with a second DAC and
TV-encoder. The flat panel add-on also connects to the video-out bus. So
you can't use a  digital flat panel and TV at the same time.

Hmm. Ok that started to steer away from the subject so I'll just stop now
:)

-- 
Ville Syrjälä
syrjala@sci.fi
http://www.sci.fi/~syrjala/


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