[Intel-gfx] [PATCH v1 0/2] drm/i915/tc: Prevent system hang when modesetting disconnected Type-C ports

[Vivek Kasireddy]

The following two patches try to prevent a system hang when a modeset
is forced by userspace (Weston) on legacy Type-C ports that are
disconnected. This issue was accidentally discovered while trying
to modeset one of the HDMI ports on the TGL based Gigabyte system
(https://www.gigabyte.com/Mini-PcBarebone/GB-BSi3-1115G4-rev-10#ov)
using the following Weston settings (configured via weston.ini):

[output]
name=HDMI-A-3
mode=173.00 1920 2048 2248 2576  1080 1083 1088 1120 -hsync +vsync
force-on=true

Entering the name of the HDMI connector incorrectly above (for example
HDMI-A-3 (disconnected) instead of HDMI-A-2 (connected)) lead to 
warnings in the log followed by a system hang. To fix this issue,
the first patch prevents the selection of TBT PLL for legacy Type-C
ports and the second one rejects any attempts to modeset disconnected
Type-C ports.

Cc: Imre Deak <imre.deak at intel.com>
Cc: José Roberto de Souza <jose.souza at intel.com>
Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>

Vivek Kasireddy (2):
  drm/i915/tc: Don't default disconnected legacy Type-C ports to TBT
    mode
  drm/i915: Reject the atomic modeset if an associated Type-C port is
    disconnected

 drivers/gpu/drm/i915/display/intel_atomic.c | 20 ++++++++++++++++++++
 drivers/gpu/drm/i915/display/intel_tc.c     |  3 ++-
 2 files changed, 22 insertions(+), 1 deletion(-)

-- 
2.35.1