null_platform_test: Disable CRTCs first

Same as https://crrev.com/c/3271634 and https://crrev.com/c/3309960;
RK3399 systems have multiple possible CRTCs for a given connector, and
if we end up choosing a different one than Chrome was using, we might
try to attach 2 CRTCs to the same connector, and the DRM modeset code
doesn't like that.

Disable all CRTCs first, to avoid that.

BUG=b:205666848, b:205666891
TEST=`tast run ${HOST} graphics.DRM.null_platform_test \
                       graphics.NullPlatformFormat.*`
TEST=... `stop ui; null_platform_test -f XB24`

Fixed: b:205666848
Change-Id: Ia3588383730bae0f600817a6c67131a74bd942dc
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/drm-tests/+/3315478
Reviewed-by: Mark Yacoub <markyacoub@google.com>
Reviewed-by: Miguel Casas-Sanchez <mcasas@chromium.org>
Reviewed-by: Miguel Casas <mcasas@google.com>
Tested-by: Brian Norris <briannorris@chromium.org>
Commit-Queue: Brian Norris <briannorris@chromium.org>
1 file changed