Monthly Archives: January 2014

Getting 1080p working via Intel i915 (Haswell 4600) -> HDMI -> VGA -> TV

For a project I recently started, I needed to build a semi-dedicated system. To make the cost a little more palatable, I planned to make it double as an HTPC (and maybe, in time, a Steam Box).

The TV I opted to use had its HDMI circuitry burn out late last year, so, as a workaround, I’ve been using an HDMI-to-VGA converter (HD2V04; does HDCP), which has been flawless with a PS3, but failed horribly when working with a device that actually wanted to trust EDID values, rather than just forcing its own fixed profiles, as a game console would.

Specifically, all EDID would enumerate was the VESA core-set and 1366×768, none of which looked good or even scaled properly on my display.

Adding definitions to xorg.conf repeatedly failed with “no mode of this name”, even when the mappings all appeared to check out. Using cvt and xrandr just resulted in unsupported video modes, making that seem like a dead-end, too. And i915.modeset=0 just made my DPI, which xorg.conf also failed to override, painfully wrong, to the point that there wasn’t enough detail to fonts to make out much of anything.

Ultimately, after lots of experimentation, I found a working configuration. The information below should work on most distributions, but have only been tested on Kubuntu 13.10.

First, you should try cvt 1920 1080 (using appropriate values), because, if it works, you’ll save yourself a bit of time. If not, then, like me, you can look for an appropriate modeline from the MythTV Modeline Database.

Once you have values, you’ll need to register them so xrandr will know what “1920×1080” means: xrandr --newmode "1920x1080" 148.50 1920 2008 2052 2200 1080 1084 1089 1125 +hsync +vsync

Then bind the new mode to the output you’re using: xrandr --addmode HDMI3 1920x1080 (you can find the name of your output, HDMI3 in my case, by running xrandr without arguments)

Finally, set the mode and refresh-rate to see if it works: xrandr --output HDMI3 --mode "1920x1080" --rate 60

If it doesn’t, you can set another mode, even if you can’t see your screen, by typing xrandr --output HDMI3 --mode "1024x768" --rate 60, which is almost certain to exist. (You can see all modes by typing xrandr without arguments)

Once you have a working value, you can make it permanent on-login by putting it in ~/.xprofile, which is executed as a series of instructions like any other script. I added a shebang and made the file executable for testing purposes, but this is probably not necessary.
[code]
#!/bin/sh
xrandr –newmode "1920×1080" 148.50 1920 2008 2052 2200 1080 1084 1089 1125 +hsync +vsync
xrandr –addmode HDMI3 1920×1080
xrandr –output HDMI3 –mode "1920×1080" –rate 60
[/code]