[DP-MST] igt@kms_atomic_transition@.* - fail - Failed assertion: output->pending_pipe != b->pending_pipe

(kms_atomic_transition:1927) igt_kms-CRITICAL: Test assertion failure function igt_display_refresh, file ../lib/igt_kms.c:2265:
(kms_atomic_transition:1927) igt_kms-CRITICAL: Failed assertion: output->pending_pipe != b->pending_pipe
(kms_atomic_transition:1927) igt_kms-CRITICAL: DP-7 and eDP-1 are both trying to use pipe C
Dynamic subtest pipe-C failed.
**** DEBUG ****
(kms_atomic_transition:1927) igt_kmod-DEBUG: Unknown symbol in module sw_sync or unknown parameter
(kms_atomic_transition:1927) sw_sync-DEBUG: Test requirement passed: kernel_has_sw_sync()
(kms_atomic_transition:1927) igt_fb-DEBUG: igt_create_fb_with_bo_size(width=1024, height=768, format=XR24(0x34325258), modifier=0x0, size=0)
(kms_atomic_transition:1927) igt_fb-DEBUG: igt_create_fb_with_bo_size(handle=8, pitch=4096)
(kms_atomic_transition:1927) ioctl_wrappers-DEBUG: Test requirement passed: igt_has_fb_modifiers(fd)
(kms_atomic_transition:1927) igt_kms-DEBUG: display: DP-5: set_pipe(C)
(kms_atomic_transition:1927) igt_kms-DEBUG: display: DP-5: Selecting pipe C
(kms_atomic_transition:1927) igt_kms-DEBUG: display: commit {
(kms_atomic_transition:1927) igt_kms-CRITICAL: Test assertion failure function igt_display_refresh, file ../lib/igt_kms.c:2265:
(kms_atomic_transition:1927) igt_kms-CRITICAL: Failed assertion: output->pending_pipe != b->pending_pipe
(kms_atomic_transition:1927) igt_kms-CRITICAL: DP-7 and eDP-1 are both trying to use pipe C
(kms_atomic_transition:1927) igt_core-INFO: Stack trace:
(kms_atomic_transition:1927) igt_core-INFO: #0 ../lib/igt_core.c:1712 __igt_fail_assert()
(kms_atomic_transition:1927) igt_core-INFO: #1 [igt_display_refresh.isra.36+0x163]
(kms_atomic_transition:1927) igt_core-INFO: #2 ../lib/igt_kms.c:2892 do_display_commit()
(kms_atomic_transition:1927) igt_core-INFO: #3 ../lib/igt_kms.c:3537 igt_display_commit2()
(kms_atomic_transition:1927) igt_core-INFO: #4 ../tests/kms_atomic_transition.c:217 run_transition_test()
(kms_atomic_transition:1927) igt_core-INFO: #5 ../tests/kms_atomic_transition.c:936 __real_main905()
(kms_atomic_transition:1927) igt_core-INFO: #6 ../tests/kms_atomic_transition.c:905 main()
(kms_atomic_transition:1927) igt_core-INFO: #7 ../csu/libc-start.c:344 __libc_start_main()
(kms_atomic_transition:1927) igt_core-INFO: #8 [_start+0x2a]
**** END ****
Dynamic subtest pipe-C: FAIL (0.005s)