It looks to be the (expired ) bug #1451632 drm:intel fifo

It looks like upstream kernel doesn't solve completely the problem:

uname -a
Linux carlosLT 4.4.0-040400-generic #201601101930 SMP Mon Jan 11 00:32:41 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux

However, it does no hangs anymore when I switch nouveau<->nvidia (355.11). No need to restart.

This bug can also be followed at: https://bugs.freedesktop.org/show_bug.cgi?id=89806

Carlos

Thanks form the A17 INFO Christopher.
After BIOS update the
carlos@carlosLT:~$ sudo dmidecode -s bios-version && sudo dmidecode -s bios-release-date
A17
08/19/2015

A restart, and, I still have the same issue: No improvement.

carlos@carlosLT:~$ dmesg | grep drm:intel
[ 1.595212] [drm:intel_set_pch_fifo_underrun_reporting [i915]] *ERROR* uncleared pch fifo underrun on pch transcoder A
[ 1.595250] [drm:intel_pch_fifo_underrun_irq_handler [i915]] *ERROR* PCH transcoder A FIFO underrun

Carlos

carlos palma, in order to allow additional upstream developers to examine the issue, at your earliest convenience, could you please test the latest upstream kernel available from http://kernel.ubuntu.com/~kernel-ppa/mainline/?C=N;O=D ? Please keep in mind the following:
1) The one to test is at the very top line at the top of the page (not the daily folder).
2) The release names are irrelevant.
3) The folder time stamps aren't indicative of when the kernel actually was released upstream.
4) Install instructions are available at https://wiki.ubuntu.com/Kernel/MainlineBuilds .

If testing on your main install would be inconvenient, one may:
1) Install Ubuntu to a different partition and then test this there.
2) Backup, or clone the primary install.

If the latest kernel did not allow you to test to the issue (ex. you couldn't boot into the OS) please make a comment in your report about this, and continue to test the next most recent kernel version until you can test to the issue. Once you've tested the upstream kernel, please comment on which kernel version specifically you tested. If this issue is fixed in the mainline kernel, please add the following tags by clicking on the yellow circle with a black pencil icon, next to the word Tags, located at the bottom of the report description:
kernel-fixed-upstream
kernel-fixed-upstream-X.Y-rcZ

Where X, and Y are the first two numbers of the kernel version, and Z is the release candidate number if it exists.

If the mainline kernel does not fix the issue, please add the following tags:
kernel-bug-exists-upstream
kernel-bug-exists-upstream-X.Y-rcZ

Please note, an error to install the kernel does not fit the criteria of kernel-bug-exists-upstream.

Once testing of the latest upstream kernel is complete, please mark this report's Status as Confirmed. Please let us know your results.

Thank you for your understanding.

OK. I'll do that now ...

Great. With upstream version below,
carlos@carlosLT:~$ uname -a
Linux carlosLT 4.5.0-040500rc1-generic #201601241731 SMP Sun Jan 24 22:33:12 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux

and I have three errors now:

carlos@carlosLT:~$ dmesg | grep ERROR
[ 39.837796] [drm:intel_set_cpu_fifo_underrun_reporting [i915]] *ERROR* uncleared fifo underrun on pipe A
[ 39.837809] [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe A FIFO underrun
[ 39.837834] [drm:intel_set_pch_fifo_underrun_reporting [i915]] *ERROR* uncleared pch fifo underrun on pch transcoder A
[ 39.837843] [drm:intel_pch_fifo_underrun_irq_handler [i915]] *ERROR* PCH transcoder A FIFO underrun

I will continue testing upstream and inform ...
Thanks,
Carlos