Bug 219128

Created attachment 182379 [details]
dmesg.log

I'm using Macbook Air 2012 for FreeBSD-11.0R.

I found my Mini-DisplayPort to VGA adapter doesn't work
to add second display for my presentation.

I don't think my adapter is broken,
because I rebooted my Macbook Air with OS X, it works.
And I remember my adapter worked on FreeBSD-10.3R.

On my FreeBSD-11.0R,
I've seen following dmesg, since I attached the adapter.

```
$ dmesg | tail -5
error: [drm:pid0:intel_dp_i2c_aux_ch] *ERROR* too many retries, giving up
error: [drm:pid0:intel_dp_i2c_aux_ch] *ERROR* too many retries, giving up
error: [drm:pid0:intel_dp_i2c_aux_ch] *ERROR* too many retries, giving up
error: [drm:pid0:intel_dp_i2c_aux_ch] *ERROR* too many retries, giving up
error: [drm:pid0:intel_dp_i2c_aux_ch] *ERROR* too many retries, giving up

$ uname -a
FreeBSD air 11.0-RELEASE-p9 FreeBSD 11.0-RELEASE-p9 #0: Tue Apr 11 08:48:40 UTC 2017     root@amd64-builder.daemonology.net:/usr/obj/usr/src/sys/GENERIC  amd64

```

According to `https://wiki.freebsd.org/Intel_GPU`,
I got debug messages with `sysctl hw.dri.debug=2`.
See the attached `dmesg.log` file.

For my hardware information,
I attach `devinfo.log` and `pciconf.log`.

For software information,
I attach `kldstat.log`, `pkginfo.log` and `Xorg.0.log`.