HDMI CEA mode
Published on November 29, 2012
This is just a quick note regarding something we found in the Linux kernel last week.
After swapping monitors to an LG W2361VG (a 23" monitor with a DVI input port), I noticed that the screen resolution kept coming up at 640x480, even though the bootargs was specifying 720P resolution.
After much digging through the kernel drivers, I found that most of the modes reported by the monitor over EDID were being rejected by a piece of code in drivers/video/mxc_hdmi.c which was looking up the resolution in an embedded table in drivers/video/mxc/mxc_edid.c.
Tracing through the ramifications, it doesn't appear that this restriction is necessary, and in fact, removing the requirement seems to work just fine, so we pushed a patch to both of our active kernel branches: