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.

Disable dithering on M1/M2 devices

NewDwarf

mirza BTW, what device you use?

I tried it on MacBook Pro M1 2020.

mirza

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

NewDwarf

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

mirza

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

NewDwarf

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.

mirza

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

mirza

Once again, maybe it's placebo, but I have feeling things did improve somewhat after this command in terminal. Would be nice if some other folks try this a give some feedback.

JesHD

Hello! I have MacBook Air 2022 M2 and have tried this command. Output is ok. After 30 min of testing it seems that I have feeling better. More testing is needed.

Thank you, NewDwarf!

mirza

I'm not sure anymore 😃 I hoped that it's at least better on my external display (closed MacBook) but I have burning eyes again, stiff neck etc. I guess I need whole day to test it properly.

NewDwarf

mirza MacBook Pro’s have PWM. So it can be side effect of PWM.

To get clean and reliable results, it would be nice to get MacBook Air 2022 user feedbacks as many as possible.

insta42014

mirza To get rid of PWM you need to use it above 50% brightness setting, you can use the Iris software to reduce brightness artificially (https://iristech.co) while keeping the real brightness setting above 50%

You can find the PWM test in this review: https://www.notebookcheck.net/Apple-MacBook-Air-2020-M1-Entry-Review-Apple-M1-CPU-humbles-Intel-and-AMD.508057.0.html

mirza

I have MacBook Air M1 2020

NewDwarf

mirza It uses PWM.

mirza

@insta42014 - I tried everything possible, nothing worked so far. Will try to return it to my local autorised resseler, if that doesn't work will try to sell it.

NewDwarf

mirza I will update the initial message of this thread. The command should be extended.

mirza

NewDwarf Thanks mate! I look forward. I wish there is a solution to this.

NewDwarf

mirza Just updated.

mirza

Sorry, but I didn't feel any difference, compared to my monitor which is plugged to pc, I get this immidiate pressure in my neck, sort of like this macbook display is shooting me 🙂 Maybe Apple doesn't allow this to change at all. I dunno.

NewDwarf

mirza It is interesting whether that part of the driver is executed at all…

Let's check it by the command

log show --process 0 | grep "applying boot-arg"

mirza

works something for a while, and then shows nothing, just goes to new line again

NewDwarf

mirza Thanks for the check. This means that the class IOMobileFramebufferLegacy (which contains the dithering control code) is not used.

Ok, then I have to look for the dithering control in other classes.

NewDwarf

mirza Could you please also grep for the keyword "IOMobileFramebuffer"?