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commit fecd062121e47bc1ffaa926b3be56e43946129c8
parent 0f32e478e9f0014ab36e57b94407f686d11575f5
Author: Francis Rowe <>
Date:   Mon, 19 Oct 2015 03:21:08 +0100

docs/hcl/gm45_lcd.html: Notes about LVDS dual/single auto-detect

docs/hcl/gm45_lcd.html | 18++++--------------
1 file changed, 4 insertions(+), 14 deletions(-)

diff --git a/docs/hcl/gm45_lcd.html b/docs/hcl/gm45_lcd.html @@ -44,25 +44,15 @@ Current workaround: </h1> <p> - T500/R400 are clones of the T400. See <b>coreboot/src/mainboard/lenovo/t400/devicetree.cb</b> in libreboot, - and note that <b>register "gfx.lvds_dual_channel" = "0"</b> - in other words, single channel LVDS mode is - enforced. This works on the lower resolution panels (1280x800), but not on the higher ones. - </p> - <p> - For the high-res panels, re-compiling with <b>register "gfx.lvds_dual_channel" = "1"</b> partially solves - the problem for those displays; there is still no display in GRUB, but once the kernel takes over, there - is a display. - </p> - <p> - Linux (kernel) has its own init code (including EDID parsing). The current suspicion is that coreboot's - own initialization code has buggy EDID parsing in some way, such that the proper settings for the panel - are not used, leading to the failure. The actual graphics initialization does work. + Libreboot (git, and releases after 20150518) now automatically detect whether + to use single or dual link LVDS configuration. If you're using an older version, + use the instructions below. </p> <p> The i915 module in the Linux kernel also provides an option to set the LVDS link configuration. lvds_channel_mode:Specify LVDS channel mode (0=probe BIOS [default], 1=single-channel, 2=dual-channel) (int) - - from /sbin/modinfo i915 + - from /sbin/modinfo i915 - use <b>lvds_channel_mode=2</b> as a kernel option in grub.cfg. </p> </div>