Question about the video device driver

[Geert Uytterhoeven]

On Fri, 7 Jan 2000, Shuangjun Zhu wrote:
> The video of MPC823 FADS board only support YCbYCr mode,
> so how can I write a device driver for the video of MPC823 FADS board,
> to enable the X?
> 
> Any suggestion? 
> Thanks in advanced.

This sounds like an interesting project.

How many bits per pixel are available? If it's not too much you can create a
staticcolor visual and consider it to be a simple paletted video mode (with a
static palette). However, IIRC, XFree86 doesn't support staticcolor hardware,
but support for that is probably closer than support for YCbCr.

I see you write YCbYCr? So the color components are subsampled like digital
broadcast video? In that case things become more complex because of the
different resolutions for the luminance and chrominance channels.

All this combined, I think the best solution is to use the virtual frame buffer
feature of XFree86 3.9.x (draw in a piece of memory as large as the screen) and
update the screen image by converting the changed parts from RGB to YCbYCr.

Does the MPC823 FADS have accelerated graphics? Accelerated RGB to YCbYCr
conversion?

I'm moving the discussion to XFree86 Devel <devel at XFree86.Org>.

> -----Original Message-----
> From: Geert Uytterhoeven <geert at linux-m68k.org>
> To: Shuangjun Zhu (r44089) <r44089 at email.sps.mot.com>
> Cc: linuxppc-dev at lists.linuxppc.org <linuxppc-dev at lists.linuxppc.org>
> Date: Tuesday, January 04, 2000 6:09 PM
> Subject: Re: Question about the video device driver
> 
> 
> >
> >On Tue, 4 Jan 2000, Shuangjun Zhu wrote:
> >> If the data format in the video memory is CbYCrY,
> >> the above layer application like Xserver can handle this?
> >
> >XFree86 doesn't do YCbCr.

Gr{oetje,eeting}s,

						Geert

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Geert Uytterhoeven ----------------- Sony Suprastructure Center Europe (SUPC-E)
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