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      <base href="https://bugs.freedesktop.org/">
    </head>
    <body>
      <p>
        <div>
            <b><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - WARNING: CPU: 11 PID: 1137 at drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm_mst_types.c:88 dm_dp_aux_transfer+0xa5/0xc0 [amdgpu]"
   href="https://bugs.freedesktop.org/show_bug.cgi?id=107456#c1">Comment # 1</a>
              on <a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - WARNING: CPU: 11 PID: 1137 at drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm_mst_types.c:88 dm_dp_aux_transfer+0xa5/0xc0 [amdgpu]"
   href="https://bugs.freedesktop.org/show_bug.cgi?id=107456">bug 107456</a>
              from <span class="vcard"><a class="email" href="mailto:marc@dragonfly.plus.com" title="Marc Thomas <marc@dragonfly.plus.com>"> <span class="fn">Marc Thomas</span></a>
</span></b>
        <pre>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 ]---</pre>
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