Bug 211807 - [drm:drm_dp_mst_dpcd_read] *ERROR* mstb 000000004e6288dd port 3: DPCD read on addr 0x60 for 1 bytes NAKed
Summary: [drm:drm_dp_mst_dpcd_read] *ERROR* mstb 000000004e6288dd port 3: DPCD read on...
Status: NEW
Alias: None
Product: Drivers
Classification: Unclassified
Component: Video(DRI - non Intel) (show other bugs)
Hardware: All Linux
: P1 low
Assignee: drivers_video-dri
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2021-02-16 20:53 UTC by Erik Quaeghebeur
Modified: 2022-04-14 06:40 UTC (History)
18 users (show)

See Also:
Kernel Version: 5.10.16
Tree: Mainline
Regression: No


Attachments
dmesg from 5.14.3 (130.32 KB, text/plain)
2021-09-16 21:49 UTC, Parker Reed
Details
dmesg 5.14.5 (130.00 KB, text/plain)
2021-09-17 19:09 UTC, Parker Reed
Details

Description Erik Quaeghebeur 2021-02-16 20:53:41 UTC
In my logs, I see the following error:


[drm:drm_dp_mst_dpcd_read] *ERROR* mstb 000000004e6288dd port 3: DPCD read on addr 0x60 for 1 bytes NAKed


It has not caused any detected issues, but I guess that if the kernel complains this loudy, it is good to report it.

This is on a laptop with a Ryzen Pro 4750U APU. I custom-build the kernel, so do not hesitate to request changing some config options to investigate.
Comment 1 naon 2021-04-25 02:50:22 UTC
I have just discovered after months of searching that I recieve this same error. I have a desktop computer than uses both a AMD WX3100 and a AMD RX570. When I turn off my monitor connected to either of my graphics cards (an effective hotplug), then turn my monitor back on, I recieve the error

[drm:drm_dp_mst_dpcd_read [drm_kms_helper]] *ERROR* mstb 000000008ff61da7 port 8: DPCD read on addr 0x60 for 1 bytes NAKed

xorg crashes, I recieve the message

[drm:drm_dp_check_act_status [drm_kms_helper]] *ERROR* Failed to get ACT after 3000ms, last status: 01

and it takes up to 40 seconds for display of the vt to resume. The longer the monitor remains off, the higher the chance that display of the vt will never resume after the monitor is turned on, needing a hard restart. This error has persisted for about 3 months, ever since i've first installed linux on this computer, on every kernel variation and build I have tried to date. Currently reproduceable on 5.11.16.
Comment 2 Paloha 2021-07-20 12:19:21 UTC
I am experiencing the aforementioned error as well.

[drm:drm_dp_mst_dpcd_read [drm_kms_helper]] *ERROR* mstb 00000000f00db6df port 0: DPCD read on addr 0x4b0 for 1 bytes NAKed

I have problems connecting my ThinkPad X1 Carbon 7gen to two external DP monitors via a ThinkPad USB-C gen2 docking station. Linux is not officially supported for this dock unfortunately. The problem is that the monitors work, but seemingly randomly they stop working, either I try to go to Ubuntu settings or try to open some program with a keyboard shortcut. The monitors flicker, then die and I have to reboot. Sometimes just reconnecting the cable works, but usually not. Sometimes when I connect my phone to the dock the monitors start working again, but most often not. There is a lot of people having these problems but I have not found any solution. In dmseg only this error appears. I am to the best of my knowledge up to date with everything, kernel, bios, firmware etc.
Comment 3 Nils Tonnätt 2021-08-27 22:02:24 UTC
Same with Radeon RX5500 and Dell P2815Q display.
Comment 4 Parker Reed 2021-09-16 21:48:50 UTC
I get full on driver "crashes" when trying two DisplayPort monitors with the aforementioned ThinkPad USB-C Gen 2 dock (T495 AMD)

I can use either or DisplaPort port but both causes the crashes.

Dmesg attached
Comment 5 Parker Reed 2021-09-16 21:49:26 UTC
Created attachment 298847 [details]
dmesg from 5.14.3
Comment 6 Parker Reed 2021-09-17 19:09:14 UTC
Created attachment 298867 [details]
dmesg 5.14.5

I can reliably get both 1440p monitors working now with pure DP but only at 60 Hz

If I try switching either one to 75 Hz it kills that monitor.

Attached new dmesg
Comment 8 Parker Reed 2021-09-17 20:55:44 UTC
Just built 5.15 rc1 (master) and I'm hung up right after bootloader. Maybe someone else can test that patch. I'll be unable to get back around to this until next week. 

Thanks for the prompt reply.
Comment 9 Nils Tonnätt 2021-09-18 11:59:05 UTC
I've tested 5.15.0-0.rc1.20210917gitbdb575f87217 from Fedora's mainline kernel repo where this is already applied. But this triggers a segfault in gnome-shell (even with DP 1.2 turned off):
[   23.621514] gnome-shell[2126]: segfault at 0 ip 0000000000000000 sp 00007ffdc1fa6af8 error 14

I'll try to patch 5.14 now.
Comment 10 Nils Tonnätt 2021-09-18 12:56:17 UTC
I patched 5.14.5. I see now difference in behavior. When the screen stays black it often works to switch to a tty or turn off and on the display. Dmesg seems to became a little more verbose about this:

[   64.800268] [drm] DM_MST: stopping TM on aconnector: 000000007957d743 [id: 97]
[   64.820206] amdgpu 0000:09:00.0: [drm] Cannot find any crtc or sizes
[   66.970887] [drm] DM_MST: starting TM on aconnector: 000000007957d743 [id: 97]
[   67.173165] amdgpu 0000:09:00.0: [drm] *ERROR* mstb 00000000ca721b5e port 8: DPCD read on addr 0x60 for 1 bytes NAKed
[   67.176906] [drm] fb mappable at 0x7C00502000
[   67.176907] [drm] vram apper at 0x7C00000000
[   67.176907] [drm] size 33177600
[   67.176908] [drm] fb depth is 24
[   67.176908] [drm]    pitch is 15360
[   67.176965] fbcon: amdgpu (fb0) is primary device
[   67.192813] amdgpu 0000:09:00.0: [drm] *ERROR* mstb 00000000ca721b5e port 8: DPCD read on addr 0x60 for 1 bytes NAKed
[   67.670123] Console: switching to colour frame buffer device 480x135
[   67.708683] amdgpu 0000:09:00.0: [drm] fb0: amdgpu frame buffer device
[   72.960002] rfkill: input handler disabled
[   73.139379] amdgpu 0000:09:00.0: [drm] *ERROR* mstb 00000000ca721b5e port 8: DPCD read on addr 0x60 for 1 bytes NAKed
[   80.216335] rfkill: input handler enabled
[   80.534571] amdgpu 0000:09:00.0: [drm] *ERROR* mstb 00000000ca721b5e port 8: DPCD read on addr 0x60 for 1 bytes NAKed
Comment 11 Matt Berry 2021-10-23 21:03:48 UTC
I'm seeing this when I use my work laptop (HP SKU 3YG73UC) with a Startech DP KVM (sv231dpu2) on Ubuntu 20.04 (5.11.0-37-generic). It doesn't happen every time, but when I switch the KVM over I'll hear the fan kick on and when I switch the KVM back I'll see the following in `dmesg`. Given that it's a work laptop, I'll have to follow their kernel release cycle, but will report back if I see it on newer kernels as they roll out.

```
sudo journalctl -b 0 | grep -i firmware | grep i915
Oct 12 14:44:59 u41fc3826021951.ant.amazon.com kernel: i915 0000:00:02.0: [drm] Finished loading DMC firmware i915/kbl_dmc_ver1_04.bin (v1.4)

sudo dmesg | egrep -vi 'audit|usb |hub |input: '
[941754.942373] [drm:drm_dp_mst_dpcd_read [drm_kms_helper]] *ERROR* mstb 000000003ba372b9 port 1: DPCD read on addr 0x4b0 for 1 bytes NAKed
[941754.964462] [drm:drm_dp_mst_dpcd_read [drm_kms_helper]] *ERROR* mstb 000000003ba372b9 port 3: DPCD read on addr 0x4b0 for 1 bytes NAKed
[941953.993504] [drm:drm_dp_mst_dpcd_read [drm_kms_helper]] *ERROR* mstb 000000003ba372b9 port 3: DPCD read on addr 0x4b0 for 1 bytes NAKed
[942109.330113] loop12: detected capacity change from 0 to 1232
[942125.974833] loop13: detected capacity change from 0 to 337424
[942146.986960] [drm:drm_dp_mst_dpcd_read [drm_kms_helper]] *ERROR* mstb 000000003ba372b9 port 3: DPCD read on addr 0x4b0 for 1 bytes NAKed
[942392.995237] [drm:drm_dp_mst_dpcd_read [drm_kms_helper]] *ERROR* mstb 000000003ba372b9 port 3: DPCD read on addr 0x4b0 for 1 bytes NAKed
[942967.950060] [drm:drm_dp_mst_dpcd_read [drm_kms_helper]] *ERROR* mstb 000000003ba372b9 port 1: DPCD read on addr 0x4b0 for 1 bytes NAKed
[942967.972573] [drm:drm_dp_mst_dpcd_read [drm_kms_helper]] *ERROR* mstb 000000003ba372b9 port 3: DPCD read on addr 0x4b0 for 1 bytes NAKed
[942990.984072] [drm:drm_dp_mst_dpcd_read [drm_kms_helper]] *ERROR* mstb 000000003ba372b9 port 3: DPCD read on addr 0x4b0 for 1 bytes NAKed
[943003.939382] [drm:drm_dp_mst_dpcd_read [drm_kms_helper]] *ERROR* mstb 000000003ba372b9 port 1: DPCD read on addr 0x4b0 for 1 bytes NAKed
[943003.962504] [drm:drm_dp_mst_dpcd_read [drm_kms_helper]] *ERROR* mstb 000000003ba372b9 port 3: DPCD read on addr 0x4b0 for 1 bytes NAKed
[943227.981538] [drm:drm_dp_mst_dpcd_read [drm_kms_helper]] *ERROR* mstb 000000003ba372b9 port 3: DPCD read on addr 0x4b0 for 1 bytes NAKed
[943765.979086] [drm:drm_dp_mst_dpcd_read [drm_kms_helper]] *ERROR* mstb 000000003ba372b9 port 3: DPCD read on addr 0x4b0 for 1 bytes NAKed
[943775.950453] [drm:drm_dp_mst_dpcd_read [drm_kms_helper]] *ERROR* mstb 000000003ba372b9 port 1: DPCD read on addr 0x4b0 for 1 bytes NAKed
[943775.981195] [drm:drm_dp_mst_dpcd_read [drm_kms_helper]] *ERROR* mstb 000000003ba372b9 port 3: DPCD read on addr 0x4b0 for 1 bytes NAKed
[944033.975975] [drm:drm_dp_mst_dpcd_read [drm_kms_helper]] *ERROR* mstb 000000003ba372b9 port 3: DPCD read on addr 0x4b0 for 1 bytes NAKed
[945830.946882] [drm:drm_dp_mst_dpcd_read [drm_kms_helper]] *ERROR* mstb 000000003ba372b9 port 1: DPCD read on addr 0x4b0 for 1 bytes NAKed
[945830.969342] [drm:drm_dp_mst_dpcd_read [drm_kms_helper]] *ERROR* mstb 000000003ba372b9 port 3: DPCD read on addr 0x4b0 for 1 bytes NAKed
[946098.985432] [drm:drm_dp_mst_dpcd_read [drm_kms_helper]] *ERROR* mstb 000000003ba372b9 port 3: DPCD read on addr 0x4b0 for 1 bytes NAKed
[947569.935525] [drm:drm_dp_mst_dpcd_read [drm_kms_helper]] *ERROR* mstb 000000003ba372b9 port 1: DPCD read on addr 0x4b0 for 1 bytes NAKed
[947569.957792] [drm:drm_dp_mst_dpcd_read [drm_kms_helper]] *ERROR* mstb 000000003ba372b9 port 3: DPCD read on addr 0x4b0 for 1 bytes NAKed
[947604.971146] [drm:drm_dp_mst_dpcd_read [drm_kms_helper]] *ERROR* mstb 000000003ba372b9 port 3: DPCD read on addr 0x4b0 for 1 bytes NAKed
```
Comment 12 zwerg12 2021-10-26 09:27:05 UTC
As mentioned before, I get the same error with a monitor connected with DP to a Lenovo ThinkPad USB-C Dock Gen2. My Laptop has an Intel i7 10510U no additional graphics card. I am using Debian testing with the provided kernel.

Furthermore sudo dmesg output says:
[  148.088024] wrong crc01 50 63 ff ff 00 00 00 00 50 63 ff ff 00 00 00
[  148.088028] wrong crc00 04 90 c0 01 00 00 00 00 00 00 00 00 00 00 00
[  148.088029] wrong crc00 00 00 00 95 00 00 00 00 00 00 00 00
[  148.152590] [drm:drm_dp_mst_dpcd_read [drm_kms_helper]] *ERROR* mstb 00000000deb5c7d4 port 1: DPCD read on addr 0x4b0 for 1 bytes NAKed
[  148.182726] [drm:drm_dp_mst_dpcd_read [drm_kms_helper]] *ERROR* mstb 00000000deb5c7d4 port 0: DPCD read on addr 0x4b0 for 1 bytes NAKed
[  148.202439] [drm:drm_dp_mst_dpcd_read [drm_kms_helper]] *ERROR* mstb 00000000deb5c7d4 port 3: DPCD read on addr 0x4b0 for 1 bytes NAKed
[  148.557719] [drm:drm_dp_mst_hpd_irq [drm_kms_helper]] *ERROR* Got unknown reply 0x00 (GET_MSG_TRANSACTION_VERSION)
[  148.812803] [drm:drm_dp_mst_dpcd_read [drm_kms_helper]] *ERROR* mstb 00000000e591bea5 port 1: DPCD read on addr 0x4b0 for 1 bytes NAKed
[  149.036253] wrong crc80 81 40 95 00 a9 40 b3 00 d1 00 e1 c0 37 38 51
[  149.036257] wrong crc56 0a 20 20 20 20 20 00 00 00 ff 00 4c 35 4c 4d
[  149.036259] wrong crc51 53 31 37 34 34 38 33 0a 01 05 02 00
[  149.119816] wrong crc80 81 40 95 00 a9 40 b3 00 d1 00 e1 c0 37 38 51
[  149.119819] wrong crc56 0a 20 20 20 20 20 00 00 00 ff 00 4c 35 4c 4d
[  149.119821] wrong crc51 53 31 37 34 34 38 33 0a 01 05 02 00
[  149.161970] wrong crc20 20 20 20 20 00 00 00 fc 00 50 41 32 37 38 51
[  149.161973] wrong crc56 0a 20 20 20 20 20 00 00 00 ff 00 4c 00 00 00
[  149.161975] wrong crc00 00 00 00 00 00 00 00 00 00 00 00
[  149.219517] wrong crc80 81 40 95 00 a9 40 b3 00 d1 00 e1 c0 37 38 51
[  149.219520] wrong crc56 0a 20 20 20 20 20 00 00 00 ff 00 4c 35 4c 4d
[  149.219522] wrong crc51 53 31 37 34 34 38 33 0a 01 05 02 00
[  149.248529] wrong crc22 02 80 00 ff ff ff ff ff ff 00 06 b3 56 5e 00
[  149.248532] wrong crca0 a0 a0 29 50 30 20 35 00 55 50 21 00 00 1a 00
[  149.248534] wrong crc00 00 fd 00 2e 4b 70 70 1e 01 0a 20 d3
[  149.357568] [drm:drm_dp_mst_dpcd_read [drm_kms_helper]] *ERROR* mstb 00000000e591bea5 port 3: DPCD read on addr 0x4b0 for 1 bytes NAKed
[  149.386520] wrong crc22 02 80 00 ff ff ff ff ff ff 00 06 b3 00 27 01
[  149.386523] wrong crc01 01 01 16 1e 01 04 a5 3c 22 78 3b ff 00 1a 00
[  149.386524] wrong crc00 00 fd 00 2e 4b 70 70 1e 01 0a 20 d3
[  149.433016] wrong crc80 81 40 95 00 a9 40 b3 00 d1 00 e1 c0 37 38 51
[  149.433019] wrong crc56 0a 20 20 20 20 20 00 00 00 ff 00 4c 35 4c 4d
[  149.433020] wrong crc51 53 31 37 34 34 38 33 0a 01 05 02 00
[  149.452176] wrong crc22 02 80 00 ff ff ff ff ff ff 00 06 b3 00 27 01
[  149.452179] wrong crc01 01 01 16 1e 01 04 a5 3c 22 78 3b ff 00 1a 00
[  149.452180] wrong crc00 00 fd 00 2e 4b 70 70 1e 01 0a 20 d3
[  149.465498] wrong crc80 81 40 95 00 a9 40 b3 00 d1 00 e1 c0 56 5e 00
[  149.465501] wrong crca0 a0 a0 29 50 30 20 35 00 55 50 21 00 35 4c 4d
[  149.465503] wrong crc51 53 31 37 34 34 38 33 0a 01 05 02 00
[  149.476472] i915 0000:00:02.0: [drm] DP-3: EDID is invalid:
[  149.476477] 	[00] BAD  00 ff ff ff ff ff ff 00 06 b3 00 27 01 01 01 01
[  149.476479] 	[00] BAD  16 1e 01 04 a5 3c 22 78 3b ff 00 1a 00 00 00 fd
[  149.476481] 	[00] BAD  00 2e 4b 70 70 1e 01 0a 20 80 81 40 95 00 a9 40
[  149.476483] 	[00] BAD  b3 00 d1 00 e1 c0 56 5e 00 a0 a0 a0 29 50 30 20
[  149.476484] 	[00] BAD  35 00 55 50 21 00 35 4c 4d 51 53 31 37 34 34 38
[  149.476486] 	[00] BAD  33 0a 01 05 02 20 20 20 20 20 00 00 00 fc 00 50
[  149.476487] 	[00] BAD  41 32 37 38 51 56 0a 20 20 20 20 20 00 00 00 ff
[  149.476489] 	[00] BAD  00 4c 35 4c 4d 51 53 31 37 34 34 38 33 0a 01 05
[  149.533039] wrong crc22 02 80 00 ff ff ff ff ff ff 00 06 b3 56 5e 00
[  149.533042] wrong crca0 a0 a0 29 50 30 20 35 00 55 50 21 00 00 1a 00
[  149.533044] wrong crc00 00 fd 00 2e 4b 70 70 1e 01 0a 20 d3
[  149.698698] wrong crc01 05 6c ff ff 00 00 00 00 05 6c ff ff 00 00 00
[  149.698702] wrong crc00 04 90 c0 01 00 00 00 00 00 00 00 00 00 00 00
[  149.698704] wrong crc00 00 00 00 95 00 00 00 00 00 00 00 00
[  149.732698] [drm:drm_dp_mst_dpcd_read [drm_kms_helper]] *ERROR* mstb 0000000076514e96 port 1: DPCD read on addr 0x4b0 for 1 bytes NAKed
[  149.750841] [drm:drm_dp_mst_dpcd_read [drm_kms_helper]] *ERROR* mstb 0000000076514e96 port 0: DPCD read on addr 0x4b0 for 1 bytes NAKed
[  149.772810] [drm:drm_dp_mst_dpcd_read [drm_kms_helper]] *ERROR* mstb 0000000076514e96 port 3: DPCD read on addr 0x4b0 for 1 bytes NAKed
[  150.080471] failed hdr00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[  154.083081] [drm:drm_dp_send_link_address [drm_kms_helper]] *ERROR* Sending link address failed with -5
[  156.605509] [drm:drm_dp_mst_dpcd_read [drm_kms_helper]] *ERROR* mstb 00000000f470192a port 1: DPCD read on addr 0x4b0 for 1 bytes NAKed
[  160.905655] wrong crc22 02 80 00 ff ff ff ff ff ff 00 06 b3 56 5e 00
[  160.905659] wrong crca0 a0 a0 29 50 30 20 35 00 55 50 21 00 00 1a 00
[  160.905661] wrong crc00 00 fd 00 2e 4b 70 70 1e 01 0a 20 d3
[  161.043938] wrong crc80 81 40 95 00 a9 40 b3 00 d1 00 e1 c0 56 5e 00
[  161.043941] wrong crca0 a0 a0 29 50 30 20 35 00 55 50 21 00 35 4c 4d
[  161.043942] wrong crc51 53 31 37 34 34 38 33 0a 01 05 02 00
[  161.355912] wrong crc22 02 80 00 ff ff ff ff ff ff 00 06 b3 00 27 01
[  161.355915] wrong crc01 01 01 16 1e 01 04 a5 3c 22 78 3b ff 00 1a 00
[  161.355916] wrong crc00 00 fd 00 2e 4b 70 70 1e 01 0a 20 d3

During this my notebook monitor is blinking.
This setup worked for around four weeks when suddenly these errors occurred.
Comment 13 Alex Deucher 2021-10-26 13:09:42 UTC
(In reply to zwerg12 from comment #12)
> As mentioned before, I get the same error with a monitor connected with DP
> to a Lenovo ThinkPad USB-C Dock Gen2. My Laptop has an Intel i7 10510U no
> additional graphics card. I am using Debian testing with the provided kernel.
> 
> 
> During this my notebook monitor is blinking.
> This setup worked for around four weeks when suddenly these errors occurred.


Can you bisect?
Comment 14 Daan 2021-11-19 12:25:30 UTC
I also had this in my logs yesterday, right before my system locked completely (had to do a hard reset).

I also have a Lenovo Thinkpad Thunderbolt Dock, which connects my Thinkpad T480 with two external monitors (one Hdmi, one Displayport). I didn't have this lockup before, in the past both monitors were hdmi so maybe Displayport is the culprit here?

Exact message:  i915 0000:00:02.0: [drm] *ERROR* mstb 00000000afedfd20 port 3: DPCD read on addr 0x4b0 for 1 bytes NAKed

Setup: 
Thinkpad T480, i7, UHD Graphics 620 + Nvidia Mx150
Fedora (5.14.16-201.fc34.x86_64)
Comment 15 Michel Dänzer 2021-11-19 14:35:19 UTC
(In reply to Daan from comment #14)
> I also had this in my logs yesterday, right before my system locked
> completely (had to do a hard reset).

That's probably coincidence. I get these messages on a regular basis, without any bad behaviour.
Comment 16 zwerg12 2021-11-23 15:48:38 UTC
(In reply to Alex Deucher from comment #13)
> (In reply to zwerg12 from comment #12)
> > As mentioned before, I get the same error with a monitor connected with DP
> > to a Lenovo ThinkPad USB-C Dock Gen2. My Laptop has an Intel i7 10510U no
> > additional graphics card. I am using Debian testing with the provided
> kernel.
> > 
> > 
> > During this my notebook monitor is blinking.
> > This setup worked for around four weeks when suddenly these errors
> occurred.
> 
> 
> Can you bisect?

I have never done it yet. But as soon as I am at home I can try.

(In reply to Michel Dänzer from comment #15)
> (In reply to Daan from comment #14)
> > I also had this in my logs yesterday, right before my system locked
> > completely (had to do a hard reset).
> 
> That's probably coincidence. I get these messages on a regular basis,
> without any bad behaviour.

Sometimes when I get this message there is no bad behavior but sometimes I also have to do a hard reset. Without the docking station I never had to make a hard reset.
Comment 17 Chatty 2021-11-24 13:22:07 UTC
My setup: MS Surface Book 2 + AOC U2879G6 via Surface Dock via DisplayPort
Tested kernels: 5.10.0 / 5.15.3 / 5.16.0-rc1

When connecting I get random results of:
* monitor remains black
* monitor exhibits 1080p@60 as max resolution
* monitor exhibits 1440p@60 as max resolution
* monitor exhibits 2160p@30 as max resolution
* monitor exhibits 2160p@30 as max resolution <== desired
 
On boot of 5.16.0-rc1 its initialized with:
> i915 0000:00:02.0: [drm] Finished loading DMC firmware
> i915/kbl_dmc_ver1_04.bin (v1.4)
> [drm] Initialized i915 1.6.0 20201103 for 0000:00:02.0 on minor 0
 
In the first case I see following dmesg output (black monitor):
> i915 0000:00:02.0: [drm] *ERROR* mstb 0000000009cd3ca6 port 1: DPCD read on
> addr 0x4b0 for 1 bytes NAKed
 
In the last case I see following dmesg output (despite monitor working):
> i915 0000:00:02.0: [drm] *ERROR* mstb 00000000f4b4c9f1 port 1: DPCD read on
> addr 0x4b0 for 1 bytes NAKed
> i915 0000:00:02.0: [drm] *ERROR* mstb 00000000f4b4c9f1 port 1: DPCD read on
> addr 0x4b0 for 1 bytes NAKed
> i915 0000:00:02.0: [drm] *ERROR* mstb 00000000f4b4c9f1 port 1: DPCD read on
> addr 0x4b0 for 1 bytes NAKed
> i915 0000:00:02.0: [drm] *ERROR* mstb 00000000f4b4c9f1 port 1: DPCD read on
> addr 0x4b0 for 1 bytes NAKed
> i915 0000:00:02.0: [drm] *ERROR* mstb 00000000f4b4c9f1 port 1: DPCD read on
> addr 0x4b0 for 1 bytes NAKed
Comment 18 Renaud R. 2021-12-13 11:22:15 UTC
My setup:
* Latitude E5570 via dock DisplayPort
* Kernel: https://bugzilla.kernel.org

I randomly have blackscreen and I see in my logs (dmesg):
* i915 0000:00:02.0: [drm] *ERROR* mstb 00000000adcef9b1 port 1: DPCD read on addr 0x4b0 for 1 bytes NAKed
* [38971.851918] i915 0000:00:02.0: [drm] *ERROR* mstb 00000000adcef9b1 port 1: DPCD read on addr 0x4b0 for 1 bytes NAKed

My laptop was reinstall from and old ubuntu 18.04 to 20.04. I can't remember the kernel used in Unbuntu 18.04 but I didn't have this issue.
Comment 19 Renaud R. 2021-12-13 11:23:31 UTC
(In reply to Renaud R. from comment #18)
> My setup:
> * Latitude E5570 via dock DisplayPort
> * Kernel: https://bugzilla.kernel.org


Kernel: 5.15.7-051507-generic #202112080459 SMP
Comment 20 notsyncing 2022-03-13 08:08:47 UTC
I also have this on my laptop, using a USB-C to 3xHDMI adapter with 3 monitors. When I unplug and replug it, sometimes the screen will freeze and I have to force reboot.

log shows:

i915 0000:00:02.0: [drm] *ERROR* mstb 00000000c152fe9e port 1: DPCD read on addr 0x4b0 for 1 bytes NAKed
i915 0000:00:02.0: [drm] *ERROR* mstb 00000000c152fe9e port 2: DPCD read on addr 0x4b0 for 1 bytes NAKed

The machine also dies when resuming from suspend with the adapter plugged in, but I could not get any log, just guessing it might be the same issue.

my setup:

HP Envy 13 ad110tu (i5-8250U, UHD 620)
Archlinux with kernel 5.16.13-arch1-1 x86_64, KDE Plasma 5.24.3 on Wayland
Comment 21 Fiona Buckner 2022-04-07 15:48:20 UTC
Seeing this on Ubuntu 22.04 pre-release. Ubuntu Kernel 5.15.0-23-generic.

> # dmesg | grep i915
> [    1.776895] i915 0000:00:02.0: [drm] VT-d active for gfx access
> [    1.776899] fb0: switching to i915 from EFI VGA
> [    1.776936] i915 0000:00:02.0: vgaarb: deactivate vga console
> [    1.780003] i915 0000:00:02.0: vgaarb: changed VGA decodes:
> olddecodes=io+mem,decodes=io+mem:owns=io+mem
> [    1.780279] i915 0000:00:02.0: [drm] Finished loading DMC firmware
> i915/kbl_dmc_ver1_04.bin (v1.4)
> [    2.675796] i915 0000:00:02.0: [drm] [ENCODER:113:DDI C/PHY C] is
> disabled/in DSI mode with an ungated DDI clock, gate it
> [    2.681117] i915 0000:00:02.0: [drm] [ENCODER:120:DDI D/PHY D] is
> disabled/in DSI mode with an ungated DDI clock, gate it
> [    3.015399] [drm] Initialized i915 1.6.0 20201103 for 0000:00:02.0 on
> minor 0
> [    3.068397] fbcon: i915drmfb (fb0) is primary device
> [    3.427857] i915 0000:00:02.0: [drm] fb0: i915drmfb frame buffer device
> [   25.814835] snd_hda_intel 0000:00:1f.3: bound 0000:00:02.0 (ops
> i915_audio_component_bind_ops [i915])
> [   26.218387] mei_hdcp 0000:00:16.0-b638ab7e-94e2-4ea2-a552-d1c54b627f04:
> bound 0000:00:02.0 (ops i915_hdcp_component_ops [i915])
> [   52.090727] mei_hdcp 0000:00:16.0-b638ab7e-94e2-4ea2-a552-d1c54b627f04:
> bound 0000:00:02.0 (ops i915_hdcp_component_ops [i915])
> [   84.800055] i915 0000:00:02.0: [drm] *ERROR* mstb 000000000a940675 port 2:
> DPCD read on addr 0x4b0 for 1 bytes NAKed
> [   84.811156] i915 0000:00:02.0: [drm] *ERROR* mstb 000000000a940675 port 3:
> DPCD read on addr 0x4b0 for 1 bytes NAKed
> [ 4814.933704] audit: type=1400 audit(1649342645.891:72): apparmor="DENIED"
> operation="open" profile="snap.chromium.chromium"
> name="/proc/sys/dev/i915/perf_stream_paranoid" pid=44648 comm="chrome"
> requested_mask="r" denied_mask="r" fsuid=1000 ouid=0
> [ 7139.378349] i915 0000:00:02.0: [drm] *ERROR* mstb 000000000a940675 port 2:
> DPCD read on addr 0x4b0 for 1 bytes NAKed
> [ 7139.388678] i915 0000:00:02.0: [drm] *ERROR* mstb 000000000a940675 port 3:
> DPCD read on addr 0x4b0 for 1 bytes NAKed

Dell 
CPU: Intel® Core™ i7-9750H CPU @ 2.60GHz × 12 
GPU: Quadro T1000/PCIe/SSE2 / Quadro T1000/PCIe/SSE2
(forcing the Nvidia gpu through Nvidia Optimus because the Intel igpu isn't enough for dual 4k monitors)
Dell WD19TB dock connected to the USBC Thunderbolt port.
2x HP z27 monitors. One connected to the USBC port on the dock, the other to the Display Port.

Researching this error, I found this thread: https://lists.freedesktop.org/archives/dri-devel/2022-February/342776.html

> This is normal (although not great TBH, I'm not sure we should be printing an
> error message for that), it's the result of fwupd trying to probe the MST hub
> to see if it's a specific Dell dock that can receive updates over DP aux, but
> it's not smart enough to know it doesn't need to poke the DP aux ranges of
> downstream branches or non-MST ports in general.
> Would definitely accept patches to make this a non-error, or at least make
> this a non-error when the read/writes come from userspace
- Lyude Paul

It might be good to speak with Lyude about it as she might be the expert on it.  I hope this helps.

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