On Mon, May 28, 2012 at 1:09 AM, Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote: > A new worry about excessively verbose i915 driver "errors" that don't > actually seem to be errors. > > I got myself a micro-DP to VGA adapter so that I can use my Macbook > Air for presentations. > > And testing it, hotplugging seems to work very nicely, and gone are > the days when you had to do xrandr and crap. Things "JustWork(tm)". > > Goodie. > > Until you start looking at the dmesg log. Then it gets ugly. It's full > of scary-looking stuff like > > ------------[ cut here ]------------ > WARNING: at drivers/gpu/drm/i915/intel_dp.c:350 intel_dp_check_edp+0x5d/0xb0() > Hardware name: MacBookAir4,1 > eDP powered off while attempting aux channel communication. > Modules linked in: fuse rfcomm bnep nf_conntrack_netbios_ns > nf_conntrack_broadcast .. > Pid: 2126, comm: kworker/0:0 Tainted: G W 3.4.0-08209-gae32adc #9 > Call Trace: > warn_slowpath_common+0x7a/0xb0 > warn_slowpath_fmt+0x41/0x50 > intel_dp_check_edp+0x5d/0xb0 > intel_dp_aux_ch+0x3f/0x330 > intel_dp_aux_native_read_retry+0xad/0x130 > intel_dp_detect+0x240/0x2c0 > output_poll_execute+0xba/0x1a0 > process_one_work+0x11b/0x3c0 > worker_thread+0x12e/0x2d0 > kthread+0x8e/0xa0 > kernel_thread_helper+0x4/0x10 > ---[ end trace 5756a4d08d9e2a83 ]--- > > which seems a bit extreme. I just unplugged the connector, I don't > think it should necessarily make quite this big a deal over it. What > does the WARN_ON() with the full call trace really buy us? Well, all these edp checks (I presume all the other WARN backtraces yell around about edp, too) ensure that we have edp vdd or the panel power on while we try to do dp aux channel communication. And because we do need to talk to the monitor at tons of places, the backtrace is actually really useful to debug such edp vdd confusions. The real problem here is that we think that the DP connector on your MBA is connected to an edp panel, which is pretty bogus. Cc'ing Chris and Keith who have the hw. Btw, you don't see all that dmesg spam until you connect something real because we check the hotplug pin status before we try to do use the dp aux channel (to get at the edid). Yours, Daniel PS: Add cc's and changed the subject, I've figured you wanted to bash me in public ;-) -- Daniel Vetter daniel.vetter@xxxxxxxx - +41 (0) 79 365 57 48 - http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
