On Jan 30, 2005, at 2:07 AM, Jean Delvare wrote: >> The BT869 seems to fit none of these categories through, seems to be >> neither a video4linux nor a framebuffer driver from the description, >> it seems to just export some config stuff via /proc. > > I assume you mean the bt869 *driver*, not the BT869 chip. You're right, > it doesn't follow any standard nor fit in any video subsystem. I think > it was a hack by Philip Edelbrock to get the things up and working > quickly. Since he was used to sensor drivers, he naturally wrote the > bt869 driver in the exact same way. "Hack"? Hey, hey! (Just teasing ;') Yes, it was a stab at getting the chip working and the lm-sensors driver architecture fit like a glove to make it work. Granted its utility is better fitting in a different project, hopefully a video related one. > >> What is the point of that driver? > > Allow people to configure the chip by writing to procfs. As I > understand > it, you can change things like resolution, TV standard, video connector > and a few other things. The doc here says it all: > http://www2.lm-sensors.nu/~lm78/cvs/browse.cgi/lm_sensors2/doc/chips/ > bt869 > Yes, it provides simple access to the chip's registers to turn video out 'on' and to tell it the format of data fed to it. In a nutshell, you set up the video card by getting X going in a video-compatible mode-line, and then you tell the BT869 the format (e.g. resolution, broadcast standard, etc.). The chip is pretty simple. It's a modulator and outputs video blanking at the right moments. It relies on the video card chipset to feed it a constant stream of data at a compatible resolution and timing for analog broadcast video. > > I also wonder if the BT869 chip was ever seen on non-banshee/voodoo > boards. > Yes, I think it's used on GeForce(2/3/4) and TNT(2) cards. Here's a list I found. I'm not sure how current it is: http://tvtool.cust.nearlyfreespeech.net/cardbase_t.htm That said, I don't know how many folks are using this driver vs. something else like nvtv. Phil
