On Wed, 2016-08-31 at 11:23 -0700, James Bottomley wrote: > On Fri, 2016-08-26 at 09:10 -0400, James Bottomley wrote: > > We seem to have an xrandr regression with skylake now. What's > > happening is that I can get output on to a projector, but the > > system is losing video when I change the xrandr sessions (like > > going from a --above b to a --same-as b). The main screen goes > > blank, which is basically a reboot situation. Unfortunately, I > > can't seem to get the logs out of systemd to see if there was a > > dump to dmesg (the system was definitely responding). > > > > I fell back to 4.6.2 which worked perfectly, so this is definitely > > some sort of regression. I'll be able to debug more fully when I > > get back home from the Linux Security Summit. > > I'm home now. Unfortunately, my monitor isn't as problematic as the > projector, but by flipping between various modes and separating and > overlaying the panels with --above and --same-as (xrandr), I can > eventually get it to the point where the main LCD panel goes black > and can only be restarted by specifying a different mode. > > This seems to be associated with these lines in the X > > [ 14714.389] (EE) intel(0): failed to set mode: Invalid argument [22] > > But the curious thing is that even if this fails with the error > message once, it may succeed a second time, so it looks to be a > transient error translation problem from the kernel driver. > > I've attached the full log below. > > This is only with a VGA output. I currently don't have a HDMI > dongle, but I'm in the process of acquiring one. After more playing around, I'm getting thousands of these in the kernel log (possibly millions: the log wraps very fast): [23504.873606] [drm:intel_dp_start_link_train [i915]] *ERROR* failed to train DP, aborting And then finally it gives up with [25023.770951] [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe B FIFO underrun [25561.926075] [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe A FIFO underrun And the crtc for the VGA output becomes non-responsive to any configuration command. This requires a reboot and sometimes a UEFI variable reset before it comes back. James _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
