On Wed, May 30, 2012 at 08:39:13AM -0700, Linus Torvalds wrote:
On Wed, May 30, 2012 at 1:27 AM, Daniel Vetter daniel@ffwll.ch wrote:
Ok, Chris couldn't reproduce this on his mba. Can you please boot with drm.debug=0xe, reproduce the noise and then attach the full dmesg?
Hmm. Now *I* can't reproduce it either.
I have updated my system in the meantime, so maybe this is related to that. However, I suspect it's more likely that it's some race condition, because when I got it, I got a *lot* of it, but they were all very tightly bunched together:
[ 1588.996413] WARNING: at drivers/gpu/drm/i915/intel_dp.c:350 intel_dp_check_edp+0x5d/0xb0() [ 1588.996650] WARNING: at drivers/gpu/drm/i915/intel_dp.c:350 intel_dp_check_edp+0x5d/0xb0() [ 1589.000983] WARNING: at drivers/gpu/drm/i915/intel_dp.c:350 intel_dp_check_edp+0x5d/0xb0() [ 1589.001225] WARNING: at drivers/gpu/drm/i915/intel_dp.c:350 intel_dp_check_edp+0x5d/0xb0() [ 1589.005975] WARNING: at drivers/gpu/drm/i915/intel_dp.c:350 intel_dp_check_edp+0x5d/0xb0() [ 1589.006218] WARNING: at drivers/gpu/drm/i915/intel_dp.c:350 intel_dp_check_edp+0x5d/0xb0() [ 1589.010980] WARNING: at drivers/gpu/drm/i915/intel_dp.c:350 intel_dp_check_edp+0x5d/0xb0() [ 1589.011224] WARNING: at drivers/gpu/drm/i915/intel_dp.c:350 intel_dp_check_edp+0x5d/0xb0() [ 1589.015976] WARNING: at drivers/gpu/drm/i915/intel_dp.c:350 intel_dp_check_edp+0x5d/0xb0() [ 1589.016211] WARNING: at drivers/gpu/drm/i915/intel_dp.c:350 intel_dp_check_edp+0x5d/0xb0() [ 1589.020986] WARNING: at drivers/gpu/drm/i915/intel_dp.c:350 intel_dp_check_edp+0x5d/0xb0() [ 1589.021232] WARNING: at drivers/gpu/drm/i915/intel_dp.c:350 intel_dp_check_edp+0x5d/0xb0()
ie that's 12 of those warnings (each of them with that huge backtrace etc), but they are all within 0.03 seconds of each other. So I suspect it needs to hit some particular timing window, and I was just (un)lucky.
Because when I try it now with DRM debugging, I can't hit it. And just to make sure, I re-did the test without debugging too (in case the debugging would have changed timing), but can't reproduce it that way either.
Hm, that's pretty strange that you can't reproduce this any more. We check this has_edp stuff once at boot and then never touch it again. Getting all these backtraces in close bunches is expected, because we have a lot of these checks - because we've had a lot of bugs :(. Did you by chance upgrade the firmware or switch from efi booting to bios booting - we use the vbios to detect part of the edp configuration?
The only other thing I could think of is whether disabling the internal panel changes anything. Iirc that's an edp panel on macbook airs, so this could paper over most of the warnings if it's enabled. -Daniel