[joevt]

I’m not sure how the difference between DisplayPort 1.2 and DisplayPort 1.4 affects HDR. The DisplayPort 1.2 spec can be found on the internet but doesn’t mention HDR. The DisplayPort 1.4 spec cannot be found.

Somehow, Apple enables HDR for connections made to Intel graphics (iGPU). I have a Mac mini 2018 with Intel UHD Graphics 630 which can do HDR from Thunderbolt (iGPU DisplayPort 1.2 connected -> Titan Ridge Thunderbolt controller) and HDMI (iGPU DisplayPort 1.2 -> MegaChips MCDP2920A4 DisplayPort 1.4 to HDMI 2.0b). I can’t say how well it appears since I’m not a HDR expert. I can only say if macOS makes the HDR option available and when my display indicates that it detects an HDR input.

I don’t know the difference between a static and dynamic HDR signal and an SDR signal. Maybe Apple is using static HDR signal. They could setup the GPU to output the necessary stuff for HDR even without DisplayPort 1.4 features (maybe the only thing missing from DisplayPort 1.4 is HBR3 and DSC and some other stuff not necessary for static HDR).

macOS can allow DisplayPort to HDMI adapters that support HDR to get HDR from iGPU.

Some adapters may require a firmware update to get HDR support in macOS (Club 3D CAC-1080, Club 3D CAC-1085, Cable Matters 201388).

Some adapters, such as the CAC-1080, can do HDR from iGPU at 4K60.

Some adapters, such as the CAC-1085 and Cable Matters 201388, may only work at 4K30 if DisplayPort 1.4 is not supported (maybe because DisplayPort 1.2 can’t do 4:2:0 and the adapter doesn’t do RGB/4:4:4 to 4:2:0 conversion or maybe they need another firmware update to enable that?).

I’m not sure what category the CAC-2504 is in since I don’t have one. I would guess it’s in the CAC-1080 category. It would be helpful if Club-3d listed what chip was used in each adapter (and their latest firmware version if they have an updater for it).

The CAC-1586 is probably similar to the CAC-1085?

The CAC-1504 is probably similar to the CAC-1070/CAC-2070?

Maybe Club-3d should group adapters by chip/capability instead of connector so I don’t get the USB-C version if I already have the DisplayPort version.

 

[joevt]

Forget what I said. The CAC-1510 has a real problem.

I have three of them. Two CAC-1510-A (HDCP OFF) and one CAC-1510 (HDCP ON). I don’t use them very often so I didn’t realize how bad the problem can be.

Of course, the CAC-1510 (HDCP ON) doesn’t produce an image with my Apple 30″ Cinema Display and macOS – the screen is black but it flickers the same as the black rectangle test image.

All the adapters appear to flicker. Connecting the adapters to a Thunderbolt dock doesn’t help.

I’m using the Intel GPU of a Intel Mac mini 2018. So it’s not a problem with M1 Macs. Normally, I use my Apple 30″ Cinema Display with a GTX 680 that has two Dual Link DVI ports – which have no problem with the display.

Only workaround is to not look at black screens… Black text on white background is ok but you may see some of the pixels in some of the black text flicker occasionally.

The flicker is not a loss of sync. It’s just outputting incorrect pixels every frame in varying locations. It mostly affects black pixels. It’s very noticeable with a black rectangle. The problem is greatly reduced when the black rectangle is changed to 5% brightness instead of 0% brightness.

Is the adapter doing something dumb like converting DisplayPort to analog and then converting that to Dual Link DVI?

I believe DisplayPort and DVI use 8b/10b encoding so there shouldn’t be a problem with a bunch of zero bits being transmitted.

Is it a problem having to do with limited range RGB (supporting 16-235 instead of 0-255)? If that were the case then colors would look off but they are not, and white pixels would be affected.

My firmwares are:
Club-3D CAC-1510-A HDCP OFF: HDCP_OFF_HD3_V1 2.33.102
Club-3D CAC-1510-A HDCP OFF (doesn’t have HDCP OFF on the label): same as above
Club-3D CAC-1510 HDCP ON: HDCP_ON_HD3_V1 2.33.102
(all of these use the Synaptics VMM2320)

I see Dell has an older firmware update for fixing flickering with a Dell U2417H display. I don’t know if it’s for the same kind of flickering.
https://www.dell.com/support/home/en-ca/drivers/driversdetails?driverid=tgjch

[joevt]

DisplayPort and Dual Link DVI are both digital signals.

On the DisplayPort side, the signal is four lanes of HBR which is only 2.7 Gbps.

On the Dual Link DVI side, the signal is only 6 lines of 1.65 Gbps (plus clock).

They have to be really noisy for flickering to happen (or the adapter is poorly designed). Maybe you have some devices nearby causing interference?

Maybe flickering can be removed by adding a USB or Thunderbolt dock between the adapter and Mac. The dock might be able to improve the DisplayPort side of the adapter.

[joevt]

Can you describe the solution? Which firmware version worked for you?

[joevt]

If the adapter doesn’t work, then you send a request to [email protected]

If they have a firmware update, then they will send you links for download and instructions. You will need Windows to apply the firmware update (BootCamp should also work). The firmware updater might have a function to save the old firmware in case you want to go back to the old firmware.

 

[joevt]

It looks like it should work. (I am looking at the specs – I don’t have experience with the CSV-1534)

The CSV-1534 dock supports 4 lanes of HBR2 and USB 2.0 and power delivery.

The Huawei P20 should be able to support the same.

[joevt]

M1 Macs don’t give any useful diagnostic info so I can’t say what’s going on. On an Intel Mac, I would use the AGDCDiagnose command to get some info.

M1 Macs don’t use display overrides so we can’t do workarounds for some problems.

The CAC-1510 requires four lanes of HBR to support 2560×1600 mode. The M1 Mac should be capable of that.

Maybe try connecting the adapter to a Thunderbolt 3 dock. The HP Thunderbolt Dock G2 has a USB-C port that is part of a MST Hub which might be useful because it can convert two lanes HBR2 or HBR3 to four lanes of HBR (in case some lanes aren’t working).

I you want to try adding a custom resolution, the timings for the supported modes are:
[code]
[email protected] 49.306kHz 71.00MHz h(48 32 80 +) v(3 6 14 -)
[email protected] 98.529kHz 268.00MHz h(48 32 80 +) v(3 6 37 -)
[/code]
but M1 Macs don’t use display overrides so it probably won’t help to create a custom timing.

What does the script at https://gist.github.com/joevt/e862b0088ef58b9144877d01401bcee8 show?

 

[joevt]

You are getting 1280×800? Is it 1280×800 HiDPI (smooth text) or 1280×800 scaled up to 2560×1600 (blocky, pixelated)?

See if the 2560×1600 option exists in SwitchResX?

[joevt]

[email protected] has sent me some firmware updates for the CAC-1080 and the CAC-1085 so now I can select High Dynamic Range in the Displays preferences panel of macOS Big Sur 11.5.2. I have not tested earlier macOS versions.

I’ve updated my list at   #21  with the new firmware versions.

[joevt]

Does the AGDCDiagnose command show information from the AMDD300? AMD D300 is old so it might not.

/System/Library/Extensions/AppleGraphicsControl.kext/Contents/MacOS/AGDCDiagnose -a > AGDCDiagnose_a.txt 2>&1

Run the command for each situation. Give each file a different name describing the situation. use the Finder to compress/zip the results and post somewhere.

Situations:
1) Connect the TV to the HDMI port.
2) Connect the TV to the adapter.
3) Connect an AOC monitor to the adapter.

Some of these situations can be done at the same time (#1 and #3).

Use SwitchResX to try different modes on the TV. Try 3840×2160 30Hz to start with.

[joevt]

Intel UHD might refer to the GPU that’s integrated in the CPU (iGPU for short).

Are the displays connected to Nvidia or Intel? See this in the Device Manager, change to View by Connection, then find the displays.

Displays sporadically turning off/on means a bad connection (if you feel that this is not a problem related to sleep – if you are always moving the mouse then it shouldn’t be falling asleep). Therefore try a shorter/different cable – but the dock comes with a short USB-C cable. Are you not using that cable?

Does the problem occur with only one display connected to DisplayPort?

Does the problem occur with only one display connected to HDMI?

A dock doesn’t have drivers. It will have drivers for its component parts. This dock consists of a USB 3.0 hub for the USB ports and built-in USB devices: a USB to Ethernet adapter for the Ethernet port, a USB to SD Card reader for the SD Card slots, a USB Audio device for the audio in/out port, and a DisplayPort 1.2 MST Hub for the display outputs. There may be a driver for the USB hub, a driver for the Ethernet adapter, a driver for the SD Card reader, a driver for the audio port, a driver for any USB devices connected (mouse/keyboard/storage device) and a display driver (Intel or Nvidia) for the MST Hub and any displays connected to the MST Hub. Most of the drivers should be built-in or come from the manufacturer of the individual devices. Connected to the MST Hub is a DisplayPort to VGA adapter and a DisplayPort to HDMI adapter (or they might be built into the hub). I don’t think this is a driver issue. Maybe a driver or firmware update could make it less susceptible to display connection issues by ignoring disconnections that last only a short period of time but probably not.

 

[joevt]

If there was a problem with the cable, then you wouldn’t get an image. I don’t think HDMI 2.0 does link training so it doesn’t detect bad cables and force lower link rate like DisplayPort or Thunderbolt or PCIe or HDMI 2.1 does.

For 4K 60Hz, you need to use 8bpc to use 444.

In macOS BigSur, for the CAC-1080, macOS chooses 420 for HDMI timing 594MHz but it will choose 444 when using CVT-RB timing 533 MHz. It’s annoying because macOS doesn’t let you change the bpc (except if you can choose HDR then you know you are using 10 bpc). One can create an EDID override (at least on Intel Macs) to remove the 420 option but then HDR wouldn’t be possible. I haven’t been able to use HDR with the CAC-1080 – but I can with a firmware updated CAC-1085 (my CAC-1080 already has the latest firmware update). I can use the AGDCDiagnose command on an Intel Mac to get output pixel format and timing info.

In Ubuntu, the xrandr --verbose command shows the current timing but I”m not sure how to see the output pixel format. It seems to me that Linux doesn’t normally support 10bpc so there’s no reason for it to choose 4:2:0. In my test, using 60Hz 133kHz 533MHz or 60Hz 135kHz 594MHz the chroma subsampling test image was clear. Which Linux are you using? What GPU?

In Windows, there’s an option to change the bpc and the pixel format. For 4K60Hz, I can choose:
4:4:4/RGB 8bpc
4:2:2 8, 10, 12 bpc
4:2:0 8, 10, 12 bpc
but sometimes the display goes black or shows static or has the wrong colors (I’m using AMD RX 580 with the CAC-1080 – Radeon Software is garbage – sometimes the Displays tab in Radeon Software Settings disappears). Windows has an HDR option but I can’t get it to work properly (Radeon Software problems?). With a CAC-1085, I can get HDR but only at 30Hz – the Radeon Software won’t let me choose 4K 60Hz 10bpc 4:2:0 HDR at the same time.

 

[joevt]

What MacBook Pro model do you have? What macOS are you using?

Every MacBook or MacBook Pro with a Thunderbolt or USB-C port supports USB-C DisplayPort Alt Mode.

The M1 MacBook Pro can only connect one display via Thunderbolt ports.

You may be limited to 8.64 Gbps if your MBP only supports DisplayPort 1.2.
You may be limited to 12.96 Gbps if your MBP supports DisplayPort 1.4 but not DSC.
Full HDMI 2.0b is 14.4 Gbps.
If your MBP supports DSC, it might not be enabled by default in Big Sur.

The CSV-1593 contains a DisplayPort MST hub to support multiple displays but macOS only supports one display from an MST hub. However, macOS can use the MST hub to convert fast/narrow DisplayPort (HBR3 x2) to slow/wide DisplayPort (HBR2x4 or HDMI in the case of the CSV-1593).

I suppose first thing you should do is to use a different display, USB-C port, OS, and/or  computer to verify that the CSV-1593 works at all.

[joevt]

DP 1.2 has more bandwidth than HDMI 2.0 but doesn’t support 4:2:0. Depending on the display and the adapter, DP 1.2 may be able to do the following 4K modes (assuming the display can do HDMI 2.1; assuming CVT-RB timing/not HDMI timing; assuming 3840×2160):

• 60Hz 10bpc 4:4:4
• 80Hz 8bpc 4:4:4
• 95Hz 10bpc 4:2:2
• 110Hz 8bpc 4:2:2

The Pascal series of Nvidia cards should be able to support DisplayPort 1.4 but they do not support DSC which the CAC-1085 uses to get some HDMI 2.1 modes. Without DSC, you should be able to get the following 4K timings (give or take a few Hz):

• 95Hz 10bpc 4:4:4
• 115Hz 8bpc 4:4:4
• 140Hz 10bpc 4:2:2
• 170Hz 8bpc 4:2:2
• 180Hz 10bpc 4:2:0
• 220Hz 8bpc 4:2:0

Notes:

• 10bpc is required for HDR.
• 4:4:4 uses same bandwidth as RGB.
• The adapter or display might not support some modes.

If Nvidia drivers are crashing then maybe that’s an issue for Nvidia to solve – after you make sure you have the latest drivers.

Try Linux to see if the adapter behaves better in a different OS.

[joevt]

Maybe it’s HDCP related? Having to do with playing protected content?

Use the utility in the zip attachment at
https://kb.cablematters.com/index.php?View=entry&EntryID=147
to see what the current firmware of the CAC-1010 is. It may also show if you have the HDCP ON or OFF version.

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