On the HP Zbook I've got here with an AMD WX4150 GPU, DP MST is entirely nonfunctional. The only part of MST that works is the first modeset. Every single modeset afterwards fails while spamming this in dmesg: [ 77.797646] [drm:generic_reg_wait [amdgpu]] *ERROR* REG_WAIT timeout 10us * 3000 tries - dce110_stream_encoder_dp_blank line:927 [ 77.797698] WARNING: CPU: 7 PID: 55 at drivers/gpu/drm/amd/amdgpu/../display/dc/dc_helper.c:254 generic_reg_wait+0xe7/0x160 [amdgpu] [ 77.797698] Modules linked in: fuse vfat fat arc4 rtsx_pci_sdmmc mmc_core mei_wdt rtsx_pci_ms intel_rapl memstick iTCO_wdt iTCO_vendor_support hp_wmi intel_wmi_thunderbolt wmi_bmof sparse_keymap x86_pkg_temp_thermal intel_powerclamp coretemp iwlmvm kvm mac80211 snd_hda_codec_conexant snd_hda_codec_generic snd_hda_codec_hdmi irqbypass crct10dif_pclmul crc32_pclmul snd_hda_intel snd_usb_audio snd_hda_codec ghash_clmulni_intel intel_cstate btusb snd_hda_core btrtl snd_usbmidi_lib iwlwifi intel_uncore snd_rawmidi snd_hwdep snd_seq btbcm intel_rapl_perf btintel snd_seq_device snd_pcm uvcvideo bluetooth cfg80211 videobuf2_vmalloc videobuf2_memops videobuf2_v4l2 videobuf2_common joydev videodev thunderbolt snd_timer snd media mei_me ecdh_generic i2c_i801 rtsx_pci rfkill mei soundcore intel_pch_thermal wmi [ 77.797719] acpi_pad hp_accel lis3lv02d input_polldev hp_wireless pcc_cpufreq amdgpu i915 chash gpu_sched i2c_algo_bit drm_kms_helper tg3 ttm drm serio_raw libphy e1000e crc32c_intel video [ 77.797727] CPU: 7 PID: 55 Comm: kworker/7:0 Tainted: G W 4.18.8-200.fc28.x86_64 #1 [ 77.797728] Hardware name: HP HP ZBook 15 G4/8275, BIOS P70 Ver. 01.22 05/17/2018 [ 77.797738] Workqueue: events drm_mode_rmfb_work_fn [drm] [ 77.797766] RIP: 0010:generic_reg_wait+0xe7/0x160 [amdgpu] [ 77.797766] Code: 44 24 58 8b 54 24 48 89 de 44 89 4c 24 08 48 8b 4c 24 50 48 c7 c7 80 72 a3 c0 e8 64 5f b5 ff 83 7d 20 01 44 8b 4c 24 08 74 02 <0f> 0b 48 83 c4 10 44 89 c8 5b 5d 41 5c 41 5d 41 5e 41 5f c3 41 0f [ 77.797782] RSP: 0018:ffff9c4f81aeba10 EFLAGS: 00010297 [ 77.797783] RAX: 0000000000000000 RBX: 000000000000000a RCX: 0000000000000000 [ 77.797783] RDX: 0000000000000000 RSI: ffff8ddf2f5d6938 RDI: ffff8ddf2f5d6938 [ 77.797784] RBP: ffff8ddf14c09b80 R08: 0000000000000005 R09: 0000000000010200 [ 77.797784] R10: 0000000000000000 R11: ffffffff969a11ed R12: 0000000000000bb9 [ 77.797785] R13: 0000000000004ea4 R14: 0000000000010000 R15: 0000000000000000 [ 77.797786] FS: 0000000000000000(0000) GS:ffff8ddf2f5c0000(0000) knlGS:0000000000000000 [ 77.797786] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 77.797787] CR2: 00007f2ec5105020 CR3: 000000044820a003 CR4: 00000000003606e0 [ 77.797787] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 77.797788] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 77.797788] Call Trace: [ 77.797820] dce110_stream_encoder_dp_blank+0x12c/0x1a0 [amdgpu] [ 77.797848] core_link_disable_stream+0x54/0x220 [amdgpu] [ 77.797875] dce110_reset_hw_ctx_wrap+0xc1/0x1e0 [amdgpu] [ 77.797902] dce110_apply_ctx_to_hw+0x52/0xa30 [amdgpu] [ 77.797931] ? dce_pipe_control_lock+0x1da/0x1f0 [amdgpu] [ 77.797976] dc_commit_state+0x2e7/0x580 [amdgpu] [ 77.798020] amdgpu_dm_atomic_commit_tail+0x37c/0xd70 [amdgpu] [ 77.798023] ? _cond_resched+0x15/0x30 [ 77.798024] ? wait_for_completion_timeout+0x3a/0x190 [ 77.798025] ? wait_for_completion_interruptible+0x35/0x1d0 [ 77.798053] ? dm_plane_helper_cleanup_fb+0x120/0x120 [amdgpu] [ 77.798058] commit_tail+0x3d/0x70 [drm_kms_helper] [ 77.798062] drm_atomic_helper_commit+0x103/0x110 [drm_kms_helper] [ 77.798069] drm_framebuffer_remove+0x2cc/0x3e0 [drm] [ 77.798076] drm_mode_rmfb_work_fn+0x4f/0x60 [drm] [ 77.798079] process_one_work+0x1a1/0x350 [ 77.798080] worker_thread+0x30/0x380 [ 77.798082] ? pwq_unbound_release_workfn+0xd0/0xd0 [ 77.798083] kthread+0x112/0x130 [ 77.798084] ? kthread_create_worker_on_cpu+0x70/0x70 [ 77.798086] ret_from_fork+0x35/0x40 [ 77.798087] ---[ end trace db8425ba857d73a8 ]--- [ 77.922892] [drm:generic_reg_wait [amdgpu]] *ERROR* REG_WAIT timeout 10us * 3000 tries - dce110_stream_encoder_dp_blank line:927 [ 77.922946] WARNING: CPU: 5 PID: 76 at drivers/gpu/drm/amd/amdgpu/../display/dc/dc_helper.c:254 generic_reg_wait+0xe7/0x160 [amdgpu] [ 77.922947] Modules linked in: fuse vfat fat arc4 rtsx_pci_sdmmc mmc_core mei_wdt rtsx_pci_ms intel_rapl memstick iTCO_wdt iTCO_vendor_support hp_wmi intel_wmi_thunderbolt wmi_bmof sparse_keymap x86_pkg_temp_thermal intel_powerclamp coretemp iwlmvm kvm mac80211 snd_hda_codec_conexant snd_hda_codec_generic snd_hda_codec_hdmi irqbypass crct10dif_pclmul crc32_pclmul snd_hda_intel snd_usb_audio snd_hda_codec ghash_clmulni_intel intel_cstate btusb snd_hda_core btrtl snd_usbmidi_lib iwlwifi intel_uncore snd_rawmidi snd_hwdep snd_seq btbcm intel_rapl_perf btintel snd_seq_device snd_pcm uvcvideo bluetooth cfg80211 videobuf2_vmalloc videobuf2_memops videobuf2_v4l2 videobuf2_common joydev videodev thunderbolt snd_timer snd media mei_me ecdh_generic i2c_i801 rtsx_pci rfkill mei soundcore intel_pch_thermal wmi [ 77.922969] acpi_pad hp_accel lis3lv02d input_polldev hp_wireless pcc_cpufreq amdgpu i915 chash gpu_sched i2c_algo_bit drm_kms_helper tg3 ttm drm serio_raw libphy e1000e crc32c_intel video [ 77.922977] CPU: 5 PID: 76 Comm: kworker/5:1 Tainted: G W 4.18.8-200.fc28.x86_64 #1 [ 77.922978] Hardware name: HP HP ZBook 15 G4/8275, BIOS P70 Ver. 01.22 05/17/2018 [ 77.922988] Workqueue: events drm_mode_rmfb_work_fn [drm] [ 77.923016] RIP: 0010:generic_reg_wait+0xe7/0x160 [amdgpu] [ 77.923016] Code: 44 24 58 8b 54 24 48 89 de 44 89 4c 24 08 48 8b 4c 24 50 48 c7 c7 80 72 a3 c0 e8 64 5f b5 ff 83 7d 20 01 44 8b 4c 24 08 74 02 <0f> 0b 48 83 c4 10 44 89 c8 5b 5d 41 5c 41 5d 41 5e 41 5f c3 41 0f [ 77.923033] RSP: 0018:ffff9c4f81bb3a10 EFLAGS: 00010297 [ 77.923034] RAX: 0000000000000000 RBX: 000000000000000a RCX: 0000000000000000 [ 77.923035] RDX: 0000000000000000 RSI: ffff8ddf2f556938 RDI: ffff8ddf2f556938 [ 77.923035] RBP: ffff8ddf14c09b80 R08: 0000000000000005 R09: 0000000000010200 [ 77.923036] R10: 0000000000000000 R11: ffffffff969a11ed R12: 0000000000000bb9 [ 77.923037] R13: 0000000000004ba4 R14: 0000000000010000 R15: 0000000000000000 [ 77.923038] FS: 0000000000000000(0000) GS:ffff8ddf2f540000(0000) knlGS:0000000000000000 [ 77.923039] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 77.923060] CR2: 00007f4b440d2398 CR3: 000000044820a004 CR4: 00000000003606e0 [ 77.923061] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 77.923061] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 77.923062] Call Trace: [ 77.923120] dce110_stream_encoder_dp_blank+0x12c/0x1a0 [amdgpu] [ 77.923165] core_link_disable_stream+0x54/0x220 [amdgpu] [ 77.923224] dce110_reset_hw_ctx_wrap+0xc1/0x1e0 [amdgpu] [ 77.923282] dce110_apply_ctx_to_hw+0x52/0xa30 [amdgpu] [ 77.923340] ? hwmgr_handle_task+0x6b/0xc0 [amdgpu] [ 77.923342] ? _cond_resched+0x15/0x30 [ 77.923383] ? pp_dpm_dispatch_tasks+0x41/0x60 [amdgpu] [ 77.923410] ? amdgpu_pm_compute_clocks.part.9+0xb7/0x530 [amdgpu] [ 77.923438] dc_commit_state+0x2e7/0x580 [amdgpu] [ 77.923466] amdgpu_dm_atomic_commit_tail+0x37c/0xd70 [amdgpu] [ 77.923486] ? amdgpu_bo_pin_restricted+0xd6/0x300 [amdgpu] [ 77.923488] ? _cond_resched+0x15/0x30 [ 77.923489] ? wait_for_completion_timeout+0x3a/0x190 [ 77.923489] ? wait_for_completion_interruptible+0x35/0x1d0 [ 77.923495] commit_tail+0x3d/0x70 [drm_kms_helper] [ 77.923499] drm_atomic_helper_commit+0x103/0x110 [drm_kms_helper] [ 77.923506] drm_framebuffer_remove+0x2cc/0x3e0 [drm] [ 77.923514] drm_mode_rmfb_work_fn+0x4f/0x60 [drm] [ 77.923516] process_one_work+0x1a1/0x350 [ 77.923518] worker_thread+0x30/0x380 [ 77.923519] ? pwq_unbound_release_workfn+0xd0/0xd0 [ 77.923520] kthread+0x112/0x130 [ 77.923522] ? kthread_create_worker_on_cpu+0x70/0x70 [ 77.923523] ret_from_fork+0x35/0x40 [ 77.923542] ---[ end trace db8425ba857d73a9 ]--- [ 80.360279] [drm:generic_reg_wait [amdgpu]] *ERROR* REG_WAIT timeout 10us * 3000 tries - dce110_stream_encoder_dp_blank line:927 [ 80.360333] WARNING: CPU: 4 PID: 77 at drivers/gpu/drm/amd/amdgpu/../display/dc/dc_helper.c:254 generic_reg_wait+0xe7/0x160 [amdgpu] [ 80.360334] Modules linked in: fuse vfat fat arc4 rtsx_pci_sdmmc mmc_core mei_wdt rtsx_pci_ms intel_rapl memstick iTCO_wdt iTCO_vendor_support hp_wmi intel_wmi_thunderbolt wmi_bmof sparse_keymap x86_pkg_temp_thermal intel_powerclamp coretemp iwlmvm kvm mac80211 snd_hda_codec_conexant snd_hda_codec_generic snd_hda_codec_hdmi irqbypass crct10dif_pclmul crc32_pclmul snd_hda_intel snd_usb_audio snd_hda_codec ghash_clmulni_intel intel_cstate btusb snd_hda_core btrtl snd_usbmidi_lib iwlwifi intel_uncore snd_rawmidi snd_hwdep snd_seq btbcm intel_rapl_perf btintel snd_seq_device snd_pcm uvcvideo bluetooth cfg80211 videobuf2_vmalloc videobuf2_memops videobuf2_v4l2 videobuf2_common joydev videodev thunderbolt snd_timer snd media mei_me ecdh_generic i2c_i801 rtsx_pci rfkill mei soundcore intel_pch_thermal wmi [ 80.360358] acpi_pad hp_accel lis3lv02d input_polldev hp_wireless pcc_cpufreq amdgpu i915 chash gpu_sched i2c_algo_bit drm_kms_helper tg3 ttm drm serio_raw libphy e1000e crc32c_intel video [ 80.360367] CPU: 4 PID: 77 Comm: kworker/4:1 Tainted: G W 4.18.8-200.fc28.x86_64 #1 [ 80.360368] Hardware name: HP HP ZBook 15 G4/8275, BIOS P70 Ver. 01.22 05/17/2018 [ 80.360378] Workqueue: events drm_mode_rmfb_work_fn [drm] [ 80.360408] RIP: 0010:generic_reg_wait+0xe7/0x160 [amdgpu] [ 80.360409] Code: 44 24 58 8b 54 24 48 89 de 44 89 4c 24 08 48 8b 4c 24 50 48 c7 c7 80 72 a3 c0 e8 64 5f b5 ff 83 7d 20 01 44 8b 4c 24 08 74 02 <0f> 0b 48 83 c4 10 44 89 c8 5b 5d 41 5c 41 5d 41 5e 41 5f c3 41 0f [ 80.360427] RSP: 0018:ffff9c4f81bbba10 EFLAGS: 00010297 [ 80.360428] RAX: 0000000000000000 RBX: 000000000000000a RCX: 0000000000000000 [ 80.360429] RDX: 0000000000000000 RSI: ffff8ddf2f516938 RDI: ffff8ddf2f516938 [ 80.360429] RBP: ffff8ddf14c09b80 R08: 0000000000000005 R09: 0000000000010200 [ 80.360430] R10: 0000000000000000 R11: ffffffff969a11ed R12: 0000000000000bb9 [ 80.360431] R13: 0000000000004ba4 R14: 0000000000010000 R15: 0000000000000000 [ 80.360432] FS: 0000000000000000(0000) GS:ffff8ddf2f500000(0000) knlGS:0000000000000000 [ 80.360432] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 80.360433] CR2: 0000001a66fbfd03 CR3: 000000044820a004 CR4: 00000000003606e0 [ 80.360434] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 80.360434] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 80.360435] Call Trace: [ 80.360470] dce110_stream_encoder_dp_blank+0x12c/0x1a0 [amdgpu] [ 80.360501] core_link_disable_stream+0x54/0x220 [amdgpu] [ 80.360531] dce110_reset_hw_ctx_wrap+0xc1/0x1e0 [amdgpu] [ 80.360560] dce110_apply_ctx_to_hw+0x52/0xa30 [amdgpu] [ 80.360593] ? dce_pipe_control_lock+0x1da/0x1f0 [amdgpu] [ 80.360622] dc_commit_state+0x2e7/0x580 [amdgpu] [ 80.360654] amdgpu_dm_atomic_commit_tail+0x37c/0xd70 [amdgpu] [ 80.360676] ? amdgpu_bo_pin_restricted+0xd6/0x300 [amdgpu] [ 80.360679] ? _cond_resched+0x15/0x30 [ 80.360680] ? wait_for_completion_timeout+0x3a/0x190 [ 80.360681] ? wait_for_completion_interruptible+0x35/0x1d0 [ 80.360687] commit_tail+0x3d/0x70 [drm_kms_helper] [ 80.360691] drm_atomic_helper_commit+0x103/0x110 [drm_kms_helper] [ 80.360700] drm_framebuffer_remove+0x2cc/0x3e0 [drm] [ 80.360708] drm_mode_rmfb_work_fn+0x4f/0x60 [drm] [ 80.360710] process_one_work+0x1a1/0x350 [ 80.360713] worker_thread+0x30/0x380 [ 80.360714] ? pwq_unbound_release_workfn+0xd0/0xd0 [ 80.360716] kthread+0x112/0x130 [ 80.360717] ? kthread_create_worker_on_cpu+0x70/0x70 [ 80.360719] ret_from_fork+0x35/0x40 [ 80.360720] ---[ end trace db8425ba857d73aa ]--- [ 80.436758] [drm:generic_reg_wait [amdgpu]] *ERROR* REG_WAIT timeout 10us * 3000 tries - dce110_stream_encoder_dp_blank line:927 [ 80.436795] WARNING: CPU: 5 PID: 76 at drivers/gpu/drm/amd/amdgpu/../display/dc/dc_helper.c:254 generic_reg_wait+0xe7/0x160 [amdgpu] [ 80.436795] Modules linked in: fuse vfat fat arc4 rtsx_pci_sdmmc mmc_core mei_wdt rtsx_pci_ms intel_rapl memstick iTCO_wdt iTCO_vendor_support hp_wmi intel_wmi_thunderbolt wmi_bmof sparse_keymap x86_pkg_temp_thermal intel_powerclamp coretemp iwlmvm kvm mac80211 snd_hda_codec_conexant snd_hda_codec_generic snd_hda_codec_hdmi irqbypass crct10dif_pclmul crc32_pclmul snd_hda_intel snd_usb_audio snd_hda_codec ghash_clmulni_intel intel_cstate btusb snd_hda_core btrtl snd_usbmidi_lib iwlwifi intel_uncore snd_rawmidi snd_hwdep snd_seq btbcm intel_rapl_perf btintel snd_seq_device snd_pcm uvcvideo bluetooth cfg80211 videobuf2_vmalloc videobuf2_memops videobuf2_v4l2 videobuf2_common joydev videodev thunderbolt snd_timer snd media mei_me ecdh_generic i2c_i801 rtsx_pci rfkill mei soundcore intel_pch_thermal wmi [ 80.436811] acpi_pad hp_accel lis3lv02d input_polldev hp_wireless pcc_cpufreq amdgpu i915 chash gpu_sched i2c_algo_bit drm_kms_helper tg3 ttm drm serio_raw libphy e1000e crc32c_intel video [ 80.436817] CPU: 5 PID: 76 Comm: kworker/5:1 Tainted: G W 4.18.8-200.fc28.x86_64 #1 [ 80.436818] Hardware name: HP HP ZBook 15 G4/8275, BIOS P70 Ver. 01.22 05/17/2018 [ 80.436825] Workqueue: events drm_mode_rmfb_work_fn [drm] [ 80.436850] RIP: 0010:generic_reg_wait+0xe7/0x160 [amdgpu] [ 80.436850] Code: 44 24 58 8b 54 24 48 89 de 44 89 4c 24 08 48 8b 4c 24 50 48 c7 c7 80 72 a3 c0 e8 64 5f b5 ff 83 7d 20 01 44 8b 4c 24 08 74 02 <0f> 0b 48 83 c4 10 44 89 c8 5b 5d 41 5c 41 5d 41 5e 41 5f c3 41 0f [ 80.436866] RSP: 0018:ffff9c4f81bb3a10 EFLAGS: 00010297 [ 80.436867] RAX: 0000000000000000 RBX: 000000000000000a RCX: 0000000000000000 [ 80.436868] RDX: 0000000000000000 RSI: ffff8ddf2f556938 RDI: ffff8ddf2f556938 [ 80.436868] RBP: ffff8ddf14c09b80 R08: 0000000000000005 R09: 0000000000010200 [ 80.436869] R10: 0000000000000000 R11: ffffffff969a11ed R12: 0000000000000bb9 [ 80.436869] R13: 0000000000004ea4 R14: 0000000000010000 R15: 0000000000000000 [ 80.436870] FS: 0000000000000000(0000) GS:ffff8ddf2f540000(0000) knlGS:0000000000000000 [ 80.436871] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 80.436871] CR2: 00007f3ffb9f7070 CR3: 000000044820a001 CR4: 00000000003606e0 [ 80.436872] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 80.436872] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 80.436873] Call Trace: [ 80.436902] dce110_stream_encoder_dp_blank+0x12c/0x1a0 [amdgpu] [ 80.436928] core_link_disable_stream+0x54/0x220 [amdgpu] [ 80.436953] dce110_reset_hw_ctx_wrap+0xc1/0x1e0 [amdgpu] [ 80.436996] dce110_apply_ctx_to_hw+0x52/0xa30 [amdgpu] [ 80.437034] ? hwmgr_handle_task+0x6b/0xc0 [amdgpu] [ 80.437036] ? _cond_resched+0x15/0x30 [ 80.437063] ? pp_dpm_dispatch_tasks+0x41/0x60 [amdgpu] [ 80.437083] ? amdgpu_pm_compute_clocks.part.9+0xb7/0x530 [amdgpu] [ 80.437107] dc_commit_state+0x2e7/0x580 [amdgpu] [ 80.437135] amdgpu_dm_atomic_commit_tail+0x37c/0xd70 [amdgpu] [ 80.437137] ? _cond_resched+0x15/0x30 [ 80.437137] ? wait_for_completion_timeout+0x3a/0x190 [ 80.437138] ? wait_for_completion_interruptible+0x35/0x1d0 [ 80.437139] ? _cond_resched+0x15/0x30 [ 80.437166] ? dm_plane_helper_cleanup_fb+0x120/0x120 [amdgpu] [ 80.437170] commit_tail+0x3d/0x70 [drm_kms_helper] [ 80.437173] drm_atomic_helper_commit+0x103/0x110 [drm_kms_helper] [ 80.437180] drm_framebuffer_remove+0x2cc/0x3e0 [drm] [ 80.437187] drm_mode_rmfb_work_fn+0x4f/0x60 [drm] [ 80.437189] process_one_work+0x1a1/0x350 [ 80.437190] worker_thread+0x1c9/0x380 [ 80.437192] ? pwq_unbound_release_workfn+0xd0/0xd0 [ 80.437193] kthread+0x112/0x130 [ 80.437194] ? kthread_create_worker_on_cpu+0x70/0x70 [ 80.437195] ret_from_fork+0x35/0x40 [ 80.437196] ---[ end trace db8425ba857d73ab ]--- [ 84.562602] [drm:generic_reg_wait [amdgpu]] *ERROR* REG_WAIT timeout 10us * 3000 tries - dce110_stream_encoder_dp_blank line:927 [ 84.562653] WARNING: CPU: 6 PID: 155 at drivers/gpu/drm/amd/amdgpu/../display/dc/dc_helper.c:254 generic_reg_wait+0xe7/0x160 [amdgpu] [ 84.562654] Modules linked in: fuse vfat fat arc4 rtsx_pci_sdmmc mmc_core mei_wdt rtsx_pci_ms intel_rapl memstick iTCO_wdt iTCO_vendor_support hp_wmi intel_wmi_thunderbolt wmi_bmof sparse_keymap x86_pkg_temp_thermal intel_powerclamp coretemp iwlmvm kvm mac80211 snd_hda_codec_conexant snd_hda_codec_generic snd_hda_codec_hdmi irqbypass crct10dif_pclmul crc32_pclmul snd_hda_intel snd_usb_audio snd_hda_codec ghash_clmulni_intel intel_cstate btusb snd_hda_core btrtl snd_usbmidi_lib iwlwifi intel_uncore snd_rawmidi snd_hwdep snd_seq btbcm intel_rapl_perf btintel snd_seq_device snd_pcm uvcvideo bluetooth cfg80211 videobuf2_vmalloc videobuf2_memops videobuf2_v4l2 videobuf2_common joydev videodev thunderbolt snd_timer snd media mei_me ecdh_generic i2c_i801 rtsx_pci rfkill mei soundcore intel_pch_thermal wmi [ 84.562675] acpi_pad hp_accel lis3lv02d input_polldev hp_wireless pcc_cpufreq amdgpu i915 chash gpu_sched i2c_algo_bit drm_kms_helper tg3 ttm drm serio_raw libphy e1000e crc32c_intel video [ 84.562683] CPU: 6 PID: 155 Comm: kworker/6:2 Tainted: G W 4.18.8-200.fc28.x86_64 #1 [ 84.562683] Hardware name: HP HP ZBook 15 G4/8275, BIOS P70 Ver. 01.22 05/17/2018 [ 84.562693] Workqueue: events drm_mode_rmfb_work_fn [drm] [ 84.562718] RIP: 0010:generic_reg_wait+0xe7/0x160 [amdgpu] [ 84.562719] Code: 44 24 58 8b 54 24 48 89 de 44 89 4c 24 08 48 8b 4c 24 50 48 c7 c7 80 72 a3 c0 e8 64 5f b5 ff 83 7d 20 01 44 8b 4c 24 08 74 02 <0f> 0b 48 83 c4 10 44 89 c8 5b 5d 41 5c 41 5d 41 5e 41 5f c3 41 0f [ 84.562734] RSP: 0018:ffff9c4f81ecfa10 EFLAGS: 00010297 [ 84.562735] RAX: 0000000000000000 RBX: 000000000000000a RCX: 0000000000000000 [ 84.562736] RDX: 0000000000000000 RSI: ffff8ddf2f596938 RDI: ffff8ddf2f596938 [ 84.562736] RBP: ffff8ddf14c09b80 R08: 0000000000000005 R09: 0000000000010200 [ 84.562737] R10: 0000000000000000 R11: ffffffff969a11ed R12: 0000000000000bb9 [ 84.562737] R13: 0000000000004ba4 R14: 0000000000010000 R15: 0000000000000000 [ 84.562738] FS: 0000000000000000(0000) GS:ffff8ddf2f580000(0000) knlGS:0000000000000000 [ 84.562739] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 84.562739] CR2: 0000558ee35a9408 CR3: 000000044820a006 CR4: 00000000003606e0 [ 84.562740] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 84.562740] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 84.562741] Call Trace: [ 84.562771] dce110_stream_encoder_dp_blank+0x12c/0x1a0 [amdgpu] [ 84.562797] core_link_disable_stream+0x54/0x220 [amdgpu] [ 84.562864] dce110_reset_hw_ctx_wrap+0xc1/0x1e0 [amdgpu] [ 84.562904] dce110_apply_ctx_to_hw+0x52/0xa30 [amdgpu] [ 84.562942] ? hwmgr_handle_task+0x6b/0xc0 [amdgpu] [ 84.562945] ? _cond_resched+0x15/0x30 [ 84.562972] ? pp_dpm_dispatch_tasks+0x41/0x60 [amdgpu] [ 84.562991] ? amdgpu_pm_compute_clocks.part.9+0xb7/0x530 [amdgpu] [ 84.563016] dc_commit_state+0x2e7/0x580 [amdgpu] [ 84.563043] amdgpu_dm_atomic_commit_tail+0x37c/0xd70 [amdgpu] [ 84.563062] ? amdgpu_bo_pin_restricted+0xd6/0x300 [amdgpu] [ 84.563063] ? _cond_resched+0x15/0x30 [ 84.563064] ? wait_for_completion_timeout+0x3a/0x190 [ 84.563065] ? wait_for_completion_interruptible+0x35/0x1d0 [ 84.563070] commit_tail+0x3d/0x70 [drm_kms_helper] [ 84.563074] drm_atomic_helper_commit+0x103/0x110 [drm_kms_helper] [ 84.563081] drm_framebuffer_remove+0x2cc/0x3e0 [drm] [ 84.563088] drm_mode_rmfb_work_fn+0x4f/0x60 [drm] [ 84.563090] process_one_work+0x1a1/0x350 [ 84.563092] worker_thread+0x30/0x380 [ 84.563093] ? pwq_unbound_release_workfn+0xd0/0xd0 [ 84.563095] kthread+0x112/0x130 [ 84.563096] ? kthread_create_worker_on_cpu+0x70/0x70 [ 84.563097] ret_from_fork+0x35/0x40 [ 84.563098] ---[ end trace db8425ba857d73ac ]--- [ 84.633249] [drm:generic_reg_wait [amdgpu]] *ERROR* REG_WAIT timeout 10us * 3000 tries - dce110_stream_encoder_dp_blank line:927 [ 84.633296] WARNING: CPU: 6 PID: 155 at drivers/gpu/drm/amd/amdgpu/../display/dc/dc_helper.c:254 generic_reg_wait+0xe7/0x160 [amdgpu] [ 84.633296] Modules linked in: fuse vfat fat arc4 rtsx_pci_sdmmc mmc_core mei_wdt rtsx_pci_ms intel_rapl memstick iTCO_wdt iTCO_vendor_support hp_wmi intel_wmi_thunderbolt wmi_bmof sparse_keymap x86_pkg_temp_thermal intel_powerclamp coretemp iwlmvm kvm mac80211 snd_hda_codec_conexant snd_hda_codec_generic snd_hda_codec_hdmi irqbypass crct10dif_pclmul crc32_pclmul snd_hda_intel snd_usb_audio snd_hda_codec ghash_clmulni_intel intel_cstate btusb snd_hda_core btrtl snd_usbmidi_lib iwlwifi intel_uncore snd_rawmidi snd_hwdep snd_seq btbcm intel_rapl_perf btintel snd_seq_device snd_pcm uvcvideo bluetooth cfg80211 videobuf2_vmalloc videobuf2_memops videobuf2_v4l2 videobuf2_common joydev videodev thunderbolt snd_timer snd media mei_me ecdh_generic i2c_i801 rtsx_pci rfkill mei soundcore intel_pch_thermal wmi [ 84.633317] acpi_pad hp_accel lis3lv02d input_polldev hp_wireless pcc_cpufreq amdgpu i915 chash gpu_sched i2c_algo_bit drm_kms_helper tg3 ttm drm serio_raw libphy e1000e crc32c_intel video [ 84.633325] CPU: 6 PID: 155 Comm: kworker/6:2 Tainted: G W 4.18.8-200.fc28.x86_64 #1 [ 84.633326] Hardware name: HP HP ZBook 15 G4/8275, BIOS P70 Ver. 01.22 05/17/2018 [ 84.633335] Workqueue: events drm_mode_rmfb_work_fn [drm] [ 84.633360] RIP: 0010:generic_reg_wait+0xe7/0x160 [amdgpu] [ 84.633360] Code: 44 24 58 8b 54 24 48 89 de 44 89 4c 24 08 48 8b 4c 24 50 48 c7 c7 80 72 a3 c0 e8 64 5f b5 ff 83 7d 20 01 44 8b 4c 24 08 74 02 <0f> 0b 48 83 c4 10 44 89 c8 5b 5d 41 5c 41 5d 41 5e 41 5f c3 41 0f [ 84.633376] RSP: 0018:ffff9c4f81ecfa10 EFLAGS: 00010297 [ 84.633377] RAX: 0000000000000000 RBX: 000000000000000a RCX: 0000000000000000 [ 84.633378] RDX: 0000000000000000 RSI: ffff8ddf2f596938 RDI: ffff8ddf2f596938 [ 84.633378] RBP: ffff8ddf14c09b80 R08: 0000000000000005 R09: 0000000000010200 [ 84.633379] R10: 0000000000000000 R11: ffffffff969a11ed R12: 0000000000000bb9 [ 84.633379] R13: 0000000000004ea4 R14: 0000000000010000 R15: 0000000000000000 [ 84.633380] FS: 0000000000000000(0000) GS:ffff8ddf2f580000(0000) knlGS:0000000000000000 [ 84.633381] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 84.633381] CR2: 0000558ee35a9408 CR3: 000000044820a006 CR4: 00000000003606e0 [ 84.633382] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 84.633382] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 84.633383] Call Trace: [ 84.633413] dce110_stream_encoder_dp_blank+0x12c/0x1a0 [amdgpu] [ 84.633439] core_link_disable_stream+0x54/0x220 [amdgpu] [ 84.633464] dce110_reset_hw_ctx_wrap+0xc1/0x1e0 [amdgpu] [ 84.633490] dce110_apply_ctx_to_hw+0x52/0xa30 [amdgpu] [ 84.633515] ? hwmgr_handle_task+0x6b/0xc0 [amdgpu] [ 84.633518] ? _cond_resched+0x15/0x30 [ 84.633544] ? pp_dpm_dispatch_tasks+0x41/0x60 [amdgpu] [ 84.633564] ? amdgpu_pm_compute_clocks.part.9+0xb7/0x530 [amdgpu] [ 84.633589] dc_commit_state+0x2e7/0x580 [amdgpu] [ 84.633616] amdgpu_dm_atomic_commit_tail+0x37c/0xd70 [amdgpu] [ 84.633635] ? amdgpu_bo_pin_restricted+0xd6/0x300 [amdgpu] [ 84.633636] ? _cond_resched+0x15/0x30 [ 84.633637] ? wait_for_completion_timeout+0x3a/0x190 [ 84.633638] ? wait_for_completion_interruptible+0x35/0x1d0 [ 84.633643] commit_tail+0x3d/0x70 [drm_kms_helper] [ 84.633647] drm_atomic_helper_commit+0x103/0x110 [drm_kms_helper] [ 84.633654] drm_framebuffer_remove+0x2cc/0x3e0 [drm] [ 84.633661] drm_mode_rmfb_work_fn+0x4f/0x60 [drm] [ 84.633663] process_one_work+0x1a1/0x350 [ 84.633665] worker_thread+0x30/0x380 [ 84.633666] ? pwq_unbound_release_workfn+0xd0/0xd0 [ 84.633668] kthread+0x112/0x130 [ 84.633669] ? kthread_create_worker_on_cpu+0x70/0x70 [ 84.633670] ret_from_fork+0x35/0x40 [ 84.633671] ---[ end trace db8425ba857d73ad ]--- I've observed this with both 4.18.8 and the latest upstream kernel.
The MST is working in the first modeset, and afterwards it stops working. Does it mean that each mode change after first modeset doesn't work?
(In reply to Jerry Zuo from comment #1) > The MST is working in the first modeset, and afterwards it stops working. > Does it mean that each mode change after first modeset doesn't work? Correct
Just a note: I definitely don't have the time to take a closer look at this. If someone from AMD could take a look that would be /REALLY/ appreciated.
Created attachment 141903 [details] [review] MST patch
.
(In reply to Lyude Paul from comment #3) > Just a note: I definitely don't have the time to take a closer look at this. > If someone from AMD could take a look that would be /REALLY/ appreciated. We are currently working on a MST downstream issue. The payload bw is failed to get removed for the unplugged MST monitor that exhausts payload bw. You may have a quick try to see if that helps.
I am retesting on HP Zbook.
(In reply to Jerry Zuo from comment #4) > Created attachment 141903 [details] [review] [review] > MST patch First off sorry for this taking so long. I had been prepared to test this pretty quickly originally, but there was a mixup in the office and the laptop I needed to reproduce this got sent to another office until today. So this might not get done in the time I was hoping for, but that's ok as that isn't AMD's fault. Additionally, the problem is less severe then I originally thought anyway. So, after testing a couple of kernels mst seems to work now that I'm back from XDC. I think what must have happened is I didn't get enough time to look at it closely, and got confused by two things: - The external monitors on the MST hub not coming on were most likely caused by the keypress spam from the ACPI hotplug events and I just didn't notice at the time. I have a fix for this by the way which still needs reviews! https://patchwork.freedesktop.org/patch/251897/ - I /thought/ I was actually testing hotplugging by removing the entire topology instead of just downstream sinks, as downstream sink hotplugging isn't nearly as important as the former and I kind of expected downstream sink hotplugging to be broken anyway. But, I guess not? Weird. All of that being said, that means this is a lot more severe then I thought! :), phew. ---- Now onto the actual patch that you sent: what exactly is this supposed to be doing? Are we dereferencing an mstb's port too early somewhere in the DRM MST core?
> All of that being said, that means this is a lot more severe then I thought! > :), phew. Do you mean less severe? > > ---- > Now onto the actual patch that you sent: what exactly is this supposed to be > doing? Are we dereferencing an mstb's port too early somewhere in the DRM > MST core? Imagine this daisy-chain configuration: GPU > MST display 1 > MST display 2 When unplugging MST display 2 we fail to deallocate the payload allocation for the link between the two MST displays. It looks like the MST connector destroy code tries to do so but fails to do so because it can no longer get a validate_port_ref for the 2nd MST display's port. Jerry's done a ton of debugging here and give more info. My thoughts are that it seems like Dave designed the drm_dp_mst_* code to deal with it quite well but it got broken at some point, maybe with the introduction of the validated_port_ref, or something else. But even then, all the new changes are good. I've been trying to think how this could be solved but haven't found a solution I'm happy with yet.
-- GitLab Migration Automatic Message -- This bug has been migrated to freedesktop.org's GitLab instance and has been closed from further activity. You can subscribe and participate further through the new bug through this link to our GitLab instance: https://gitlab.freedesktop.org/drm/amd/issues/534.
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