]> git.baikalelectronics.ru Git - kernel.git/commit
i915: temporary fix for DP MST docking station NULL pointer dereference
authorLinus Torvalds <torvalds@linux-foundation.org>
Thu, 30 Jul 2015 05:18:16 +0000 (22:18 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Sun, 2 Aug 2015 18:02:16 +0000 (11:02 -0700)
commit89fa4107e34055964277b3c04e3839690e9e8b28
tree6fa6838c61faa692c1512ae9932b337d6130db4a
parent6817c0cc833da5342df74b52f71e217b3ce3f58f
i915: temporary fix for DP MST docking station NULL pointer dereference

Ted Ts'o reports that his Lenovo T540p ThinkPad crashes at boot if
attached to the docking station.  This is a regression that he was able
to bisect to commit fac77fcc2b5c: "drm/i915: Use atomic helpers for
computing changed flags:"

The reason seems to be the new call to drm_atomic_helper_check_modeset()
added to intel_modeset_compute_config(), which in turn calls
update_connector_routing(), and somehow ends up picking a NULL crtc for
the connector state, causing the subsequent drm_crtc_index() to OOPS.

Daniel Vetter says that the fundamental issue seems to be confusion in
the encoder selection, and this isn't the right fix, but while he chases
down the proper fix, this at least avoids the NULL pointer dereference
and makes Ted's docking station work again.

Reported-bisected-and-tested-by: Theodore Ts'o <tytso@mit.edu>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: Mani Nikula <jani.nikula@linux.intel.com>
Cc: Dave Airlie <airlied@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
drivers/gpu/drm/drm_atomic_helper.c