D0023R
commented
3 years ago Hello Saroumane,
Indeed, enabling the composite sync at boot is driver dependent. Even if X has the possibility to specify it on the modeline flag it is not 100% certain that the graphic card bios has this functionality implemented. The current code has been done focusing on ati and nvidia cards. If you have an ATI card, there is great chanves that the Xorg solution will work for you. Regarding the kernel patch, it might be introduced at some point but its functionality will then be available if supported by the card's bios. Currently, it is only possible by combining the H+V sync signals.
Cheers
Hello,
it's more a question than an issue. My (SCART) CRT TV is connected to PC with VGA and I can boot a linux-kernel-15 khz (from groovyarcade) with parameter
video=VGA-1:640x480ieS. I tried with a cable that converts RGBHV from VGA into RGBS (composite sync) for the SCART : it works perfectly. But now I need to setup this with a "normal" cable, with "composite sync" forced by the cable.Ideally, I would like to add it a kernel parameter at boot time. It seems supported by vanilla kernel, only if you have a Matrox device : https://www.kernel.org/doc/html/latest/fb/matroxfb.html But maybe there is more universal way or your patch allows it for any device ?
If it's not possible at boot time, I think I can at least add the keyword "composite" in Modeline definition for xrandr or xorg.conf. So I guess to match resolution 640x480iSe I just have to tweak the output of
$ cvt 640 480 60 Modeline "640x480_60.00" 23.75 640 664 720 800 480 483 487 500 -hsync +vsyncby adding the keywords composite and interlace:Modeline "640x480_60.00" 23.75 640 664 720 800 480 483 487 500 -hsync +vsync composite interlaceThanks for your help.