This commit fixed the following bug: https://bugs.launchpad.net/ubuntu/quantal/+source/linux/+bug/1103856 originally affected on Thinkpad M490s laptop with v3.2 kernel, the patch also applicable on v3.2.50, v3.4.57 stable kernel and 3.5.y.z extended stable kernel, since it was merged into v3.6 kernel officially. the test was based on Ironlake laptop Thinkpad v490s and pre-Ironlake laptop Thinkpad X200 with all the stable kernel listed above. commit 520c41cf2fa029d1e8b923ac2026f96664f17c4b Author: Daniel Vetter <daniel.vetter@xxxxxxxx> Date: Wed Jul 11 16:27:52 2012 +0200 drm/i915/lvds: ditch ->prepare special case LVDS is the first output where dpms on/off and prepare/commit don't perfectly match. Now the idea behind this special case seems to be that for simple resolution changes on the LVDS we don't need to stop the pipe, because (at least on newer chips) we can adjust the panel fitter on the fly. There are a few problems with the current code though: - We still stop and restart the pipe unconditionally, because the crtc helper code isn't flexible enough. - We show some ugly flickering, especially when changing crtcs (this the crtc helper would actually take into account, but we don't implement the encoder->get_crtc callback required to make this work properly). So it doesn't even work as advertised. I agree that it would be nice to do resolution changes on LVDS (and also eDP) whithout blacking the screen where the panel fitter allows to do that. But imo we should implement this as a special case a few layers up in the mode set code, akin to how we already detect simple framebuffer changes (and only update the required registers with ->mode_set_base). Until this is all in place, make our lives easier and just rip it out. Also note that this seems to fix actual bugs with enabling the lvds output, see: http://lists.freedesktop.org/archives/intel-gfx/2012-July/018614.html Cc: Takashi Iwai <tiwai@xxxxxxx> Cc: Giacomo Comes <comes@xxxxxxxx> Acked-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> Tested-by: Takashi Iwai <tiwai@xxxxxxx> Signed-Off-by: Daniel Vetter <daniel.vetter@xxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html