Created attachment 120990 [details] dmesg | grep -C3 drm X has recently become unusable in my Debian-testing install on Thinkpad X30: it starts OK but soon after logging in (via lighdm into XFCE), the screen goes black. I can switch to vt1 where the console is displayed properly, but the vt showing X11 stays desperately pitch dark. During the boot (and even before X11 is launched) I saw some error messages including: [drm:drm_calc_timestamping_constants [drm]] *ERROR* crtc 23: Can't calculate constants, dotclock = 0! and [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe B FIFO underrun So I rebooted with "drm.debug=6". Find the resulting "grep -C3 drm" output attached.
I forgot to mention: this is running Debian's linux-image-4.3.0-1-686-pae kernel.
Is this issue still seen with latest kernel?
I've been running an older kernel since then, so I can't say right now. I'll try it next week when I have access to that machine again and will let you know.
I just tried with Debian's 4.8.0-1-686 and it seems that this problem is gone there. OTOH it seems that suspend is broken again (more specifically, I can suspend but after resume the screen stays black and it seems that the machine is completely non-responsive (typing `reboot` blindly didn't have any effect)). I'm now compiling 4.9 to confirm.
Closing, please re-open if issue seen still.
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