HDMI CEA mode

Published on November 29, 2012

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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:

If you're experiencing similar things, you might want to pull in this patch, or upgrade to our latest.