For those of my dedicated readers (I don’t think there are any) you may be disappointed by my long hiatus. I sure won’t be correcting that now.
I wanted to add to the collective knowledge of the internet by explaining how I got my Westinghouse LCD TV (SK-26H240S) with a VGA input to work as my computer monitor under Linux. Towards taht end, I will be using as many keywords as I can think of to help make this information go far and wide. Fancy-pants people who run windows need not read on, as somehow windows can just figure these things out, whereas Linux cannot.
I’m running Xorg 7.1 on Gentoo, although everything should work on just about any version of Xorg or XFree. I had to manually enter a Mode line (via the Modeline directive in my xorg.conf file) to indicate the timing and resolution for the screen. According the the xorg.conf man page you need basically 9 entries to specify a modeline: DotClock (a.k.a. Pixel Clock), HTimings (hdisp hsyncstart hsyncend htotal), and VTimings (vdisp vsyncstart vsyncend vtotal). I also specified the HSync and VSync.
I was going for the native resolution of 1360×768. For this setting, the pixel clock is given in the manual as 72. The horizontal and vertical totals are given (1520 and 790, respectively), the horizontal and vertical displays are given (1360 and 768, respectively), but the other two “start” and “end” values are not; the manual instead supplied “sync” (32 and 5) and “back porch” (80 and 15) values, which are not the same as what I need.
I tried to figure out these values from a product sheet I found, but couldn’t quite do it. However, I managed to reverse-engineer them from the XFree Modeline calculator: the start timing is “display + back porch” and the end timing is “total – sync”. Thus, the modeline is:
Modeline “1360×768@60″ 72 1360 1392 1440 1520 768 773 775 790
In researching this post, I found a tool that figures out the modeline for you… but you need to figure out the front porch from the total.
