Hey guys. I just had a chance to take a look quickly at the M1 GPU driver. At the first glance, dithering can also be controlled by the NVRAM variable. In the case of M1 chipset and its driver, this parameter is "enableDither". So, to disable dithering on M1 devices, open the terminal in normal mode (NVRAM variables are controlled from the normal mode on M1 devices) and enter the command sudo nvram boot-args="enableDither=0 PE_i_can_has_debugger=1 iomfb_RuntimeProperty_enableDither=0" and type your password. To verify the command was accepted, use the command: log show --process 0 | grep "Dither" The expected output is: xxxx-xx-xx xx:xx:xx 0x180b Default 0x0 0 0 kernel: (Sandbox) System Policy: nvram(831) allow boot-arg-set enableDither I am not sure this will help as most of M1 devices have pretty low frequency PWM. But some devices, like MacBook AIR 2022 has no PWM. It would be nice to get your feedback. Just type what exactly device you use and your feeling… Update1: the command was extended to sudo nvram boot-args="enableDither=0 PE_i_can_has_debugger=1 iomfb_RuntimeProperty_enableDither=0" Update2: macOS Ventura has redesigned approach of using kernel extensions. More likely, this solution doesn’t work there. So try it on all earlier macOS versions.

I get Error setting variable - 'boot-args': (iokit/common) not permitted.

mirza Did you try in normal or recovery mode?

Both I get same error, in normal and recovery mode…

mirza and you used it with sudo? If yes, please enter in recovery mode, open the terminal there and disable the SIP by the command “csrutil disable” Then enter the normal mode and try again to set the nvram parameter.

mirza BTW, what device you use? I tried it on MacBook Pro M1 2020.

NewDwarf Yes, MacBook Air M1 2020 here too. I think I managed to do it now, here is when I tap log show command: 2022-11-18 20:26:09.371933+0100 0x1f7ba Error 0x0 0 0 kernel: (Sandbox) System Policy: nvram(3532) deny(1) boot-arg-set enableDither 2022-11-18 20:28:15.041513+0100 0x1fba6 Error 0x0 0 0 kernel: (Sandbox) System Policy: nvram(3561) deny(1) boot-arg-set enableDither 2022-11-18 20:30:26.325331+0100 0x1ff72 Error 0x0 0 0 kernel: (Sandbox) System Policy: nvram(3592) deny(1) boot-arg-set enableDither 2022-11-18 20:35:55.447516+0100 0x1797 Error 0x0 0 0 kernel: (Sandbox) System Policy: nvram(791) deny(1) boot-arg-set enableDither 2022-11-18 20:37:44.060383+0100 0x1678 Error 0x0 0 0 kernel: (Sandbox) System Policy: nvram(703) deny(1) boot-arg-set enableDither 2022-11-18 21:43:40.607977+0100 0x250e Default 0x0 0 0 kernel: (Sandbox) System Policy: nvram(1290) allow boot-arg-set enableDither 2022-11-18 21:43:40.607984+0100 0x250e Default 0x0 0 0 kernel: [System Event] [9361451525] [INFO] [Subsystem: nvram] [Event: write] boot-args to enableDither=0 2022-11-18 21:48:05.225821+0100 0x3bd9 Default 0x0 0 0 kernel: (Sandbox) System Policy: nvram(1672) allow boot-arg-set enableDither 2022-11-18 21:48:05.225835+0100 0x3bd9 Default 0x0 0 0 kernel: [System Event] [15712279907] [INFO] [Subsystem: nvram] [Event: write] boot-args to enableDither=0

mirza thanks. Do you feel any effect of this command?

NewDwarf Difficult to say right away, I will test it and let you know. Thanks a lot.. Do you feel any difference?

mirza I sit about 10 minutes after entering this command. Currently, I don't have this laptop on the hand and I can check only on Monday. As my laptop has PWM, I can still have side effect of PWM. It would be nice if one who have MacBook Air 2022 check this command as according to reports it is PWM free.

It's probably placebo, but I have a feeling it's better. We'll see.

Disable dithering on M1/M2 devices

NewDwarf

dirtydenim Thanks. If the log command returns nothing, this means this part of the driver is not used and the boot parameters we passed by the nvram command don’t work.

…it is sad, but it requires more effort by digging in other directions.

mirza

@NewDwarf - Make an app that disables this, and set price whatever you want, you have hundreds of customers who will buy it 100% 😃

NewDwarf

mirza BTW, I can see the output of log show --process 0 | grep "IOMobileFramebufferLegacy"

2022-11-21 0xbb Default 0x0 0 0 kernel: (IOMobileGraphicsFamily) virtual bool IOMobileFramebufferLegacy::start(IOService *)

mirza

NewDwarf I get nothing..

NewDwarf

mirza Hmm…

It's interesting you got nothing. This is important string in the log which gives a hope to disable dithering.

I use macOS Monterey (12.4).

Also, it is unclear why there is no feedback from others.

mirza

NewDwarf

https://www.dropbox.com/s/5117eizi36fc6pp/kext.zip?dl=0

Reminder, now I'm on macOS Monterey

JesHD

NewDwarf after last update command my output log is:

2022-11-19 19:09:32.853323+0300 0x3497 Default 0x0 0 0 kernel: (Sandbox) System Policy: nvram(2318) allow boot-arg-set enableDither

2022-11-19 19:09:32.853327+0300 0x3497 Default 0x0 0 0 kernel: (Sandbox) System Policy: nvram(2318) allow boot-arg-set iomfb_RuntimeProperty_enableDither

MacBook Air M2 2022 macOS Monterey (12.6)

mirza

NewDwarf My OS is 12.6.1, is there a way to downgrade to 12.4

ryans

Curious how the folks trying this, have you had success?

mirza

Doesn't help for me. The problem is we don't know whether this disables temporal dithering or not. I didn't use MBA for 3-4 days, and now I tried to use it, instant vertigo and neck pain, so, yeah… I hope someone else has some solution. Tried to take my MBA to the store where I bought it (authorised reseller), they said nothing is wrong with the laptop so they cannot return my money. So, before selling it, I hope someone comes with some good news…

JesHD

mirza For me the same - eye strain after entering command.

I'm currently using the temporary solution. I mirrored the internal screen using the utility BetterDisplay. And after that, I do not feel any eye strain.

I think this is because the virtual mirror monitor is 8 bit.

I also recommend disabling True Tone and Night Shift while using mirroring.

Can anyone also try and test this?

mirza

JesHD I downloaded it, I will try it. Can you tell me where you set bit depth in this app?

edit: ok got it. I mirrored the display… So you're saying when it's mirrored from MB that it's lowering bit depth?

DHSF

JesHD Thank you, thank you, thank you! This is exactly why I love this website and the exchange with other people that have similar issues. Your workaround helped me to finally use a MacBook (Air) again - still not perfect but already feeling much better. Here's what I've done:

Created a dummy with before-mentioned app.
Scaled my screen to 1256x785, 60 Hz HiDPI 16:10 (that's about 55% in the app)
Color Profile: Adobe RGB 1998 and colors are at millions iso billions of colors.

Again, it's not perfect and I'll have to test it out a bit more but plugging my MBA M2 into my monitor finally feels much better too. I don't want to jinx it and I'm hoping this could be a long-term solution.

Sentiny

JesHD thank you very much! It really helped me, I just made dummy display, mirrored it to my original display of a Macbook Pro m1 and set sRGB preset, then optimized display for dummy display and here it is - no issues.

I also tried Asahi linux for my mbp m1 and it also helped alot with eye strain symptoms. I found out that the main issue was temporal dithering or macos scaling/antialiasing issues and not PWM for me.

dadler

JesHD This also worked for me! Instant relief, much appreciated!

JesHD

mirza Yes, this is my guess.

You can check bit depth in utility SwitchResX.

For internal display it shows «Billions of colors» (10 bit), and for virtual mirror - «Millions of colors» (8 bit).

bkdo

Sentiny

I'm unable to set a dummy display as my main display without using an external monitor, would you mind sharing how you were able to set a dummy display as main while on the MacBook display itself?

Lauda89

It seems that we already have 3 success stories.

But what are the negative effects of using this method? Increased latency?

However if others have your success, we should contact the developers of that software to see what our problem may be.

Sentiny

Lauda89 As i felt it, yep. Latency is increased slightly, but you don't even notice it. And also downside is that I cant use notch area of macbook pro m1 14’ display. That’s it for now.

Imo the problem can be in temporal dithering (8-bit vs 10-bit) or in OS scaling because I played with some scale settings in Asahi Linux and also felt eye strain with some of them (those who has Asahi can try to change Scale Method from “Accurate” to “Smooth”).

JesHD

Lauda89 I noticed such a negative effect. Possible video playback issues in some apps, such as AppleTV+. Thus, in this case, it is need to disable mirroring.

DHSF

Lauda89 Well I guess I cheered too soon… woke up with a minor migraine after I already noticed a bit of the usual symptoms last night. I will have to play around with it again and test it out more, hoping it wasn’t just a placebo effect 😔