drm/atomic-helpers: Make encoder picking more robust
authorDaniel Vetter <daniel.vetter@ffwll.ch>
Mon, 3 Aug 2015 15:24:11 +0000 (17:24 +0200)
committerDaniel Vetter <daniel.vetter@ffwll.ch>
Tue, 4 Aug 2015 09:10:41 +0000 (11:10 +0200)
commit6ea76f3cade4734e73e3da842005820558b8b828
treee6b5c9c487f5134e63b981308079e9614b7bdd6a
parent42639ba554655c280ae6cb72df0522b1201f2961
drm/atomic-helpers: Make encoder picking more robust

We've had a few issues with atomic where subtle bugs in the encoder
picking logic lead to accidental self-stealing of the encoder,
resulting in a NULL connector_state->crtc in update_connector_routing
and subsequent.

Linus applied some duct-tape for an mst regression in

commit 27667f4744fc5a0f3e50910e78740bac5670d18b
Author: Linus Torvalds <torvalds@linux-foundation.org>
Date:   Wed Jul 29 22:18:16 2015 -0700

    i915: temporary fix for DP MST docking station NULL pointer dereference

But that was incomplete (the code will still oops when debuggin is
enabled) and mangled the state even further. So instead WARN and bail
out as the more future-proof option.

Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Thierry Reding <treding@nvidia.com>
Reviewed-by: Ander Conselvan de Oliveira <conselvan2@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
drivers/gpu/drm/drm_atomic_helper.c