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  • Disable Color Dither method collection

JTL
for amdgpu driver, access to the dither property via xrandr has been removed in kernels newer than 4.13.xx, but ukuu (https://www.omgubuntu.co.uk/2017/02/ukuu-easy-way-to-install-mainline-kernel-ubuntu) makes it easy to run mutiple kernels. I have stopped looking into this very much because the combo of e-ink and xrandr have fixed the problem for me. for people new to linux they should be aware also that the dither property may be something slightly different on different cards like dithering instead of dither. this can be found by using xrandr --prop. also the dither property must be set for each display

(step 1 find your kernel)
uname -r
(if the kernel is newer than 4.13.xx then get the older version)

(step 2 find your driver)
sudo lshw -c video

(step 3 find your dither property name)
xrandr --prop
(get the name of the dithering property from output as well as the name of the displays like (DP-1 etc)

then
sudo xrandr --output HDMI-1 --set "dither" "off"
sudo xrandr --output DVI-D-1 --set "dither" "off"
sudo xrandr --output DP-1 --set "dither" "off"

    andc Not sure. My feeling is the colors are not flickering so heavily like using AMD driver. I will search more info and at the same time looking for a way to detect dithering.

      it would be great if we could get in touch with these two guys

      • Authors: Dave Airlie
      • Alex Deucher
        */
        #include <drm/drmP.h>
        #include <drm/drm_edid.h>
        #include <drm/drm_crtc_helper.h>
        #include <drm/drm_fb_helper.h>
        #include <drm/amdgpu_drm.h>
        #include "amdgpu.h"
        #include "atom.h"
        #include "atombios_encoders.h"
        #include "atombios_dp.h"
        #include "amdgpu_connectors.h"
        #include "amdgpu_i2c.h"

      #include <linux/pm_runtime.h>

      if (property == adev->mode_info.dither_property) {
	struct amdgpu_connector *amdgpu_connector = to_amdgpu_connector(connector);
	/* need to find digital encoder on connector */
	encoder = amdgpu_connector_find_encoder(connector, DRM_MODE_ENCODER_TMDS);
	if (!encoder)
		return 0;

	amdgpu_encoder = to_amdgpu_encoder(encoder);

	if (amdgpu_connector->dither != val) {
		amdgpu_connector->dither = val;
		amdgpu_connector_property_change_mode(&amdgpu_encoder->base);
	}
}

        ShivaWind You could probably git log to find their email address. Assuming your polite and not "OMG FIX DRIVER YOU WRECK MY EYES" the worst case is that they ignore you, the best case is that they try and help else given the possible time constraints of working on GPU drivers all day 😛

          8 months later
          5 months later

          I believe it is possible to disable Dithering on Mac Os for Intel Video card (I'm using MacBook pro 2018 with Intel UHD Graphic 630).

          I was researching driver's code via decompiler and found some interesting configuration parameters.

          At first, I recommend looking at what kexts are loaded. This can be done using kextstat | grep Intel command.
          Here is my output:
          https://ibb.co/tCDQKMY

          I believe that the underlying issue lays one of the *Framebuffer.kext files, decompiled code for mine com.apple.driver.AppleIntelCFLGraphicsFramebuffer looks like:
          https://ibb.co/8YGC1Wh

          AppleIntelFramebufferController::getFeatureControl method seems to load data from underlying Info.Plist

          All you need to do in order to disable dithering is simply add a new parameter to the section
          IOKitPersonalities->AppleIntelFramebufferController->FeatureControl
          in file /System/Library/Extensions/AppleIntelCFLGraphicsFramebuffer.kext/Contents/Info.plist

          Right-click on FeatureControl section in the xcode, and new Number parameter.
          name: DitherDisable
          value: 1

          Here are the contents of my Info.Plist file (with new parameter included):
          https://ibb.co/dgqK0MS

          Side note: in order to actually make changes to plist inside kext, you need to disable security protection
          https://apple.stackexchange.com/a/251559/320465

          In short, reboot mac, holding Command+R until recovery utility is loaded.
          Open terminal there (from top menu), and type:
          csrutil disable

          Restart your mac normally. Now you need to add more permissions to be able to edit that file:

          cd /System/Library/Extensions/AppleIntelCFLGraphicsFramebuffer.kext/
          sudo chown $USER Contents/
          cd Contents
          sudo chown $USER Info.plist

          Edit plist file as shown above in xcode.

          Then I'd like to return file ownership back to root user:
          sudo chown root Info.plist
          cd ..
          sudo chown root Contents/

          Let me know if your eyes are better now. For me it seems to help a lot, but need few days.

          Here is proof that colors are different after fix (banding appeared on intel):
          https://ibb.co/pR807tD
          https://ibb.co/PY4PZ71

          Note: this will only work for Intel as for now. To check active video card - use activity monitor->Energy tab
          I was trying to apply similar fix for integrated AMD video card, but stuck on apple logo screen.

            And now I stuck with AMD card dithering. Whenever graphic switches to High-perf (opening Photoshop, Sketch, or simply changing power saving option to Automatic graphics switching), I notice immediate nausea. It is not as bad as with intel, but still not comfortable.

            It is really hard to explain, it is a sensation that letters are jumping, even when screen image is static. Like visual noise.

            I wonder if someone can shed a light of what this could be, inside AMDFramebuffer.kext
            https://ibb.co/pPwDFhf

            I'm particularly interested in CFG_DEF_DITH. I tried to add this parameter in Info.plist, without success.

            It seems for me that AMD driver configuration is split and duplicated among several kext, and that is hard to glue together.

            Gleb,

            is it possible make same on LInux? Which tool can I use?

              Gleb I have an Intel HD4000 Mac Mini lying around which I can't use due to strain - I will definately give this a try today.

              Can I use this code with older versions of MacOS?

              Also I am interested to know your story; when did you notice symptoms yourself on Macs or other machines, and how did you find out this kext information?

                  Gleb Id like to try this, but am a bit afraid of ruining my macos and having to reinstall. Im getting treated for heterophoria (which you might also have, ever visited a good optometrist?), Its proven to be connected from my own experience with the treatment, but sometimes not 100% treatable so Id still welcome a technical solution.

                  1. Would there be a chance to write this into a simple app that can be used on the taskbar to switch dithering on/off? Id pay you money for it.
                  2. Wasnt there an app (gfx card) that could force using integrated intel graphics even when photoshop etc. is running?

                  You can also write me at mjanas555 {that at sign} googlemail {dot} com

                  diop Please let me know if it indeed helps with symptoms.

                  • Gleb replied to this.

                        diop

                        Can I use this code with older versions of MacOS?

                        I think yes. But the final answer depends on the Kext in use. You can list Intel kext's to see if we are using same version. If there are different framebuffers, you can send me framebuffer kext and I can take a look if it has this hidden parameter.

                        when did you notice symptoms

                        I got eye strain after 3-4 months of using MacBook pro. It became worse when I changed lights in my apartment to PWM led strips. Now I do not use LED lightings, just old lightbulb, and desk lamp. Also, I switched my primary screen from MacBook screen to external Displays (Dell UP2414q). Not starring all day into MacBook screen seems to give me relief.

                        Never had any problems with most screens for 20 years. Only some crappy glossy PWM displays made me uncomfortable, but I avoided them with success.

                        how did you find out this kext information?

                        You need some sort of decompiler. I Use IDA64 with hex-rays plugin.
                        Then I went into each suspicious Kext (Show content) and pulled binary into IDA64. You are interested to decompile Unix Executable in *.kext/Contents/MacOS/:
                        https://ibb.co/JCRx1TY

                        Then in IDA - View->Open Subview->Strings (Shift+F12)
                        And try to search for Dither there. x key on the string will show all code usages for this string. Go there and press F5 for hex-rays C-like decompiled code

                        • diop replied to this.

                            Gleb Are you running Catalina? I can upgrade this Mini to the latest MacOS (as it's a late 2012 machine) before attempting this.

                            • Gleb replied to this.

                                martin Yesterday I screw up with AMD driver modification (every time I set CFG_NO_DITH - I can't restart machine anymore, stuck on logo, about 70%)

                                The way to fix is to load in recovery mode (holding command+R) and copy unmodified kexts from recovery partiyion to your /System/Library/Extensions/

                                Here I did screenshot of commands I use for restoring original kext:
                                https://ibb.co/Gt0X1YH

                                    diop I'm still on Mojave 10.14.6 (18G95) - didn't upgrade for 32bit reasons.

                                    I believe after updating I would need to do config modifications again.

                                      Gleb I cant even get the first command in terminal running - kextstat | grep Intel

                                      Martin-MacBook-Pro:~ martinjanas$ kexstat | grep Intel
                                      -bash: kexstat: command not found

                                      You are probably very experienced and so certain things seem as given, is there more dumbed down version of how to do this?

                                      Also how about installing windows 10 via bootcamp and trying to disable all of it there to see if it indeed helps your eyes? Could you do that and share the process? Its good testing ground as its easy to wipe it if it goes wrong and still keep macos intact. If it works there, then its good motivation to figure it out for macos.

                                        kextstat | grep Intel

                                        That was a typo somewhere

                                        Windows

                                        I do not have much free space currently for it. But even in MacOS flipping integrated\discrete card switch makes a HUGE difference in how fonts and colors looks. Also now it is relaxing on eyes (my gf also see a difference with and without dithering)

                                        • diop replied to this.

                                          diop Unfortunately I do not see this hidden parameter for FramebufferCapri:

                                          https://ibb.co/5RtdNR8

                                          You may try to set Dither instead of mine DitherDisable

                                          number = 0 to disable it, if I understood Framebuffer code correctly

                                          But I can't promise results. Still worth trying.

                                          • diop replied to this.

                                              Gleb I am running Mojave 10.14.3 - would upgrading OS to Catalina change the drivers installed?

                                              • Gleb replied to this.

                                                  diop

                                                  In the meantime, I wonder if you install SwitchResX https://www.madrau.com/srx_download/download.html
                                                  And reduce colors to Millions of color, instead of billions https://ibb.co/44P4CDQ

                                                  AND, more important, in System Preferences -> Display -> Color, select Generic RGB Profile instead of Color LCD https://ibb.co/hXz3JmG

                                                  Then it seems to disable (or at least reduce) dithering effects.

                                                  You can verify it on gradient image http://www.lagom.nl/lcd-test/gradient.php
                                                  It should look banded, not linear gradient as here: https://ibb.co/PY4PZ71

                                                  Can you try it and share the experience?

                                                    dev