https://bugs.freedesktop.org/show_bug.cgi?id=107456

--- Comment #1 from Marc Thomas marc@dragonfly.plus.com --- I still see this in 4.18.9.

I found that udevd is running "/usr/bin/xcmddc --i2c /dev/i2c-7 --identify" during boot and it causes these warnings to be displayed.

Latest from 4.18.9, caused by manually running "xcmddc -lv" :

[ 72.162951] WARNING: CPU: 15 PID: 1886 at drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm_mst_types.c:88 dm_dp_aux_transfer+0xa5/0xb0 [amdgpu] [ 72.162952] Modules linked in: nct6775 hwmon_vid jc42 amd64_edac_mod edac_mce_amd pci_stub vboxpci(O) vboxnetadp(O) vboxnetflt(O) vboxdrv(O) ipv6 cmac bnep nls_iso8859_1 nls_cp437 vfat fat fuse rc_pinnacle_pctv_hd em28xx_rc rc_core si2157 si2168 i2c_mux em28xx_dvb dvb_core btusb em28xx btrtl btbcm tveeprom btintel v4l2_common videodev bluetooth ecdh_generic rfkill amdkfd amd_iommu_v2 amdgpu snd_hda_codec_realtek chash i2c_dev snd_hda_codec_generic mxm_wmi wmi_bmof snd_hda_codec_hdmi gpu_sched kvm_amd ttm snd_hda_intel snd_hda_codec drm_kms_helper igb kvm snd_hda_core drm snd_hwdep ptp snd_pcm evdev psmouse irqbypass pps_core snd_timer agpgart crct10dif_pclmul crc32_pclmul fb_sys_fops crc32c_intel dca efi_pstore syscopyarea sysfillrect k10temp i2c_piix4 i2c_algo_bit serio_raw ghash_clmulni_intel snd [ 72.162985] sysimgblt efivars soundcore hwmon i2c_core ccp xhci_pci xhci_hcd wmi pcc_cpufreq button acpi_cpufreq loop dm_snapshot dm_bufio ext4 mbcache jbd2 [ 72.162995] CPU: 15 PID: 1886 Comm: xcmddc Tainted: G W O 4.18.9 #1 [ 72.162996] Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./X370 Taichi, BIOS P4.70 04/17/2018 [ 72.163053] RIP: 0010:dm_dp_aux_transfer+0xa5/0xb0 [amdgpu] [ 72.163053] Code: be 01 00 00 00 48 8b bf 50 04 00 00 5b e9 a3 99 07 00 4c 8b 46 08 8b 0e 31 d2 31 f6 48 8b bf 50 04 00 00 e8 2d 9a 07 00 eb c6 <0f> 0b 48 c7 c0 f9 ff ff ff 5b c3 0f 1f 44 00 00 41 57 41 56 41 55 [ 72.163076] RSP: 0018:ffffbe2380d9bcc8 EFLAGS: 00010286 [ 72.163077] RAX: 0000000000000005 RBX: 0000000000000007 RCX: 0000000000000238 [ 72.163078] RDX: 0000000000000001 RSI: ffffbe2380d9bd48 RDI: ffff9756f60c48a0 [ 72.163079] RBP: ffff9756f60c48a0 R08: 00000000000240c0 R09: fffffffffffffffb [ 72.163080] R10: ffffe748dfe98f40 R11: ffffbe2380d9baa8 R12: ffffbe2380d9bd48 [ 72.163081] R13: 0000000000000000 R14: 0000000000000000 R15: ffffffffc1285cd4 [ 72.163083] FS: 00007f2adf318bc0(0000) GS:ffff97571efc0000(0000) knlGS:0000000000000000 [ 72.163084] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 72.163085] CR2: 00007f2ae07d9ff0 CR3: 00000007e9802000 CR4: 00000000003406e0 [ 72.163085] Call Trace: [ 72.163094] drm_dp_i2c_do_msg+0x90/0x290 [drm_kms_helper] [ 72.163098] ? __switch_to_asm+0x34/0x70 [ 72.163104] drm_dp_i2c_xfer+0x155/0x250 [drm_kms_helper] [ 72.163110] __i2c_transfer+0x123/0x410 [i2c_core] [ 72.163112] ? __switch_to_asm+0x40/0x70 [ 72.163116] i2c_transfer+0x55/0xa0 [i2c_core] [ 72.163120] i2c_transfer_buffer_flags+0x4c/0x70 [i2c_core] [ 72.163123] i2cdev_read+0x5f/0xd0 [i2c_dev] [ 72.163125] __vfs_read+0x36/0x180 [ 72.163128] vfs_read+0x8a/0x140 [ 72.163130] ksys_read+0x4f/0xb0 [ 72.163133] do_syscall_64+0x55/0x100 [ 72.163136] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 72.163137] RIP: 0033:0x7f2ae08605e1 [ 72.163138] Code: fe ff ff 50 48 8d 3d 2e 27 0a 00 e8 49 21 02 00 66 0f 1f 84 00 00 00 00 00 48 8d 05 19 c1 0d 00 8b 00 85 c0 75 13 31 c0 0f 05 <48> 3d 00 f0 ff ff 77 57 c3 66 0f 1f 44 00 00 41 54 49 89 d4 55 48 [ 72.163159] RSP: 002b:00007ffe53d875c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 [ 72.163161] RAX: ffffffffffffffda RBX: 000000000000000a RCX: 00007f2ae08605e1 [ 72.163162] RDX: 0000000000000080 RSI: 0000000001db9d20 RDI: 000000000000000a [ 72.163162] RBP: 00007f2ae0cd1258 R08: 0000000001db9d20 R09: 0000000000000000 [ 72.163163] R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffe53d875d0 [ 72.163164] R13: 00007ffe53d876b0 R14: 00007ffe53d876b8 R15: 0000000001db1603 [ 72.163166] ---[ end trace 5078b35dfa1666e0 ]--- [ 72.413950] WARNING: CPU: 15 PID: 1886 at drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm_mst_types.c:88 dm_dp_aux_transfer+0xa5/0xb0 [amdgpu] [ 72.413951] Modules linked in: nct6775 hwmon_vid jc42 amd64_edac_mod edac_mce_amd pci_stub vboxpci(O) vboxnetadp(O) vboxnetflt(O) vboxdrv(O) ipv6 cmac bnep nls_iso8859_1 nls_cp437 vfat fat fuse rc_pinnacle_pctv_hd em28xx_rc rc_core si2157 si2168 i2c_mux em28xx_dvb dvb_core btusb em28xx btrtl btbcm tveeprom btintel v4l2_common videodev bluetooth ecdh_generic rfkill amdkfd amd_iommu_v2 amdgpu snd_hda_codec_realtek chash i2c_dev snd_hda_codec_generic mxm_wmi wmi_bmof snd_hda_codec_hdmi gpu_sched kvm_amd ttm snd_hda_intel snd_hda_codec drm_kms_helper igb kvm snd_hda_core drm snd_hwdep ptp snd_pcm evdev psmouse irqbypass pps_core snd_timer agpgart crct10dif_pclmul crc32_pclmul fb_sys_fops crc32c_intel dca efi_pstore syscopyarea sysfillrect k10temp i2c_piix4 i2c_algo_bit serio_raw ghash_clmulni_intel snd [ 72.413980] sysimgblt efivars soundcore hwmon i2c_core ccp xhci_pci xhci_hcd wmi pcc_cpufreq button acpi_cpufreq loop dm_snapshot dm_bufio ext4 mbcache jbd2 [ 72.413989] CPU: 15 PID: 1886 Comm: xcmddc Tainted: G W O 4.18.9 #1 [ 72.413989] Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./X370 Taichi, BIOS P4.70 04/17/2018 [ 72.414046] RIP: 0010:dm_dp_aux_transfer+0xa5/0xb0 [amdgpu] [ 72.414046] Code: be 01 00 00 00 48 8b bf 50 04 00 00 5b e9 a3 99 07 00 4c 8b 46 08 8b 0e 31 d2 31 f6 48 8b bf 50 04 00 00 e8 2d 9a 07 00 eb c6 <0f> 0b 48 c7 c0 f9 ff ff ff 5b c3 0f 1f 44 00 00 41 57 41 56 41 55 [ 72.414068] RSP: 0018:ffffbe2380d9bcc8 EFLAGS: 00010286 [ 72.414069] RAX: 0000000000000005 RBX: 0000000000000007 RCX: 0000000000000238 [ 72.414070] RDX: 0000000000000001 RSI: ffffbe2380d9bd48 RDI: ffff9756f60c78a0 [ 72.414071] RBP: ffff9756f60c78a0 R08: 00000000000240c0 R09: fffffffffffffffb [ 72.414072] R10: ffffe748dfe98f40 R11: ffffbe2380d9baa8 R12: ffffbe2380d9bd48 [ 72.414073] R13: 0000000000000000 R14: 0000000000000000 R15: ffffffffc1285cd4 [ 72.414074] FS: 00007f2adf318bc0(0000) GS:ffff97571efc0000(0000) knlGS:0000000000000000 [ 72.414075] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 72.414076] CR2: 00007f2ae07d9ff0 CR3: 00000007e9802000 CR4: 00000000003406e0 [ 72.414076] Call Trace: [ 72.414084] drm_dp_i2c_do_msg+0x90/0x290 [drm_kms_helper] [ 72.414086] ? __switch_to_asm+0x34/0x70 [ 72.414093] drm_dp_i2c_xfer+0x155/0x250 [drm_kms_helper] [ 72.414097] __i2c_transfer+0x123/0x410 [i2c_core] [ 72.414100] ? __switch_to_asm+0x40/0x70 [ 72.414103] i2c_transfer+0x55/0xa0 [i2c_core] [ 72.414107] i2c_transfer_buffer_flags+0x4c/0x70 [i2c_core] [ 72.414109] i2cdev_read+0x5f/0xd0 [i2c_dev] [ 72.414112] __vfs_read+0x36/0x180 [ 72.414114] vfs_read+0x8a/0x140 [ 72.414116] ksys_read+0x4f/0xb0 [ 72.414118] do_syscall_64+0x55/0x100 [ 72.414121] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 72.414122] RIP: 0033:0x7f2ae08605e1 [ 72.414122] Code: fe ff ff 50 48 8d 3d 2e 27 0a 00 e8 49 21 02 00 66 0f 1f 84 00 00 00 00 00 48 8d 05 19 c1 0d 00 8b 00 85 c0 75 13 31 c0 0f 05 <48> 3d 00 f0 ff ff 77 57 c3 66 0f 1f 44 00 00 41 54 49 89 d4 55 48 [ 72.414144] RSP: 002b:00007ffe53d875c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 [ 72.414145] RAX: ffffffffffffffda RBX: 000000000000000c RCX: 00007f2ae08605e1 [ 72.414146] RDX: 0000000000000080 RSI: 0000000001db9e50 RDI: 000000000000000c [ 72.414147] RBP: 00007f2ae0cd1258 R08: 0000000001db9e50 R09: 0000000000000000 [ 72.414147] R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffe53d875d0 [ 72.414148] R13: 00007ffe53d876b0 R14: 00007ffe53d876b8 R15: 0000000001db1663 [ 72.414150] ---[ end trace 5078b35dfa1666e1 ]---