From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <004b01bf5b05$51035440$73f102de@sjzhu> Reply-To: "Shuangjun Zhu (r44089)" From: "Shuangjun Zhu" To: "Mark Vojkovich" , "XFree86 Devel" Cc: "Linux/PPC Development" Subject: Re: Question about the video device driver Date: Mon, 10 Jan 2000 08:54:55 +0800 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Sender: owner-linuxppc-dev@lists.linuxppc.org List-Id: I'm a newbie in the X domain, where can I get the information about showfb? As I know, there is no hardware for MPC823 FADS that can do the conversion from RGB data stored in system memory, we must do it using software. So, where I should start? Any suggestion? > >On Fri, 7 Jan 2000, Geert Uytterhoeven wrote: > >> 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. > > We support static color visuals just fine. But there will be >a problem if the hardware doesn't have a macroblock size of 1x1. >It's required that you can get read the data back without losing >information. If you are sharing chroma between pixels that's >not going to work. > >> >> 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. > > Yes, shadowfb should work fine for this if the hardware can do the >conversion from RGB data stored in system memory. > > > Mark. > > > ** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/