tree 06e0915972058023e863d3e3c9c98ab7f27c5abf
parent e83234d7ef237931148b4b17834dadf57eb46c12
author Lyude Paul <lyude@redhat.com> 1561572627 -0400
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1564904008 +0200

drm/nouveau/i2c: Enable i2c pads & busses during preinit

commit 7cb95eeea6706c790571042a06782e378b2561ea upstream.

It turns out that while disabling i2c bus access from software when the
GPU is suspended was a step in the right direction with:

commit 342406e4fbba ("drm/nouveau/i2c: Disable i2c bus access after
->fini()")

We also ended up accidentally breaking the vbios init scripts on some
older Tesla GPUs, as apparently said scripts can actually use the i2c
bus. Since these scripts are executed before initializing any
subdevices, we end up failing to acquire access to the i2c bus which has
left a number of cards with their fan controllers uninitialized. Luckily
this doesn't break hardware - it just means the fan gets stuck at 100%.

This also means that we've always been using our i2c busses before
initializing them during the init scripts for older GPUs, we just didn't
notice it until we started preventing them from being used until init.
It's pretty impressive this never caused us any issues before!

So, fix this by initializing our i2c pad and busses during subdev
pre-init. We skip initializing aux busses during pre-init, as those are
guaranteed to only ever be used by nouveau for DP aux transactions.

Signed-off-by: Lyude Paul <lyude@redhat.com>
Tested-by: Marc Meledandri <m.meledandri@gmail.com>
Fixes: 342406e4fbba ("drm/nouveau/i2c: Disable i2c bus access after ->fini()")
Cc: stable@vger.kernel.org
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>