Intel confirmed no dithering on Intel arc a770

WhisperingWind Processor: i5-12450H, Graphics: Intel UHD 48EU (Xe arch), RAM: 2 × DDR4 3200 8 GB Lexar LD4S08G32C22ST

I currently use mini-PC: i7 13700h + DDR5 4800 mhz KVR48S40BD8K2-64 + Iris XE 96UE with benq bl2420z (via HDMI to DVI cable). When I switched memory to KF556S40IB-16, I got strain. I also got strain with mini-PC 8845hz + 780m even with KVR48S40BD8K2-64 modules, but a little lower level comparing to default 5600 mhz modules. After experiments with registers, we with SunnyCove switch off all dithering settings in AMD, but 780m still strain

My hope was, Intel 12..14 gen CPUs works better with DDR5 gen ram, but your config shows it can be perfectly with DDR4 3200 without issues.

To be honest, 13700h + IRIS XE good with 4800 mhz DDR5 which have standart, not OC JEDEC timings (CL40). Lowering 5600 to 4800 timings with two different RAMs, didnt helps (only RAM with 4800 CL40 max is good). Your DDR4 also seems to have standart 3200 mhz timings (CL22).

The joke is, I tested laptop with same IRIS XE (13900h) but with LPDDR4 with win11 preinstalled, I play with it in 30 min and after leaving shop, got strain. So I dont really know, does lpddr4 matters in this case, or only screen pixel inversion/FRC (keeping in mind, IRIS XE is safe)

@simplex

I have supplemented the previous answer with new information.

WhisperingWind Thank you, much appreciate it!

WhisperingWind how did you manage to switch to 6-bit output on Windows 11? I would be glad for such instruction

WhisperingWind Intel UHD730

Can you share the link for "Programmer's Reference Manual For the 2022 12th Generation …" ?

I got only 2021 (tiger lake) and registers works nice with IRIS Xe (13700h), I am wonder if UHD 12 gen has another settings

simplex

As I understand it, the purpose of bits 5-7 in the pipe misc registers has changed. I haven't looked into it deeply, so I'm not aware of any other changes (this might be the only change).

According to the comment in the i915 code, this change occurred starting with the 13th generation for desktop CPUs and starting with the 12th generation for laptop CPUs.

WhisperingWind

According to this link

https://github.com/torvalds/linux/blob/ab75170520d4964f3acf8bb1f91d34cbc650688e/drivers/gpu/drm/i915/i915_reg.h#L1717

To get pure 6-bit, I suppose you need to set

4 bit = 0 (disable dithering)

5-7 bit = 010 (6-bit pipe)

8 bit = 1 (truncate data)

Ivan_P

Also, could you share your method of checking output bit depth? (to test that changing registers truly made things)

Switching between 6 and 8+ bits is determined by this video: https://www.youtube.com/watch?v=suAR1PYFNYA. Once the player opens, you can pause it immediately at the 0-second mark. At the very beginning, there will be very contrasting waves on the gradient on 6 bits, while on 8+ bits, the gradient will be smooth without waves.

can you tell me what files and what lines in those files you changed?

Sorry, I don't know if you have any knowledge of programming. I'll describe it as it is. If it's difficult to understand, I can later upload everything to GitHub in a ready-to-build format.

This line https://github.com/skawamoto0/ditherig/blob/2fb5b3a3b8edc405c3427757e1213cc9fcafbc9f/ditherig/ditherig.cpp#L625C1-L626C1 is responsible for forming a new value that will be written to the register. We need to clear bits 4-7 and then set the 6th bit. Bits are counted from right to left starting at zero. This way, we will disable dithering if it was enabled by default (by clearing the 4th bit of the register) and set the color depth to 6 bits on output (bits 5-7 of the register are responsible for this; 010 - 6-bit output; 000 - 8-bit output). It should look something like this:

if(ReadPhysicalMemory(Address + RegisterAddress, &Old, RegisterSize))
{
	New = Old;
	New = (New & ~RegisterMask) | (RegisterData & RegisterMask);

       // { new code starts here

	New &= 0xFFFFFF0F;
        // enable 6-bit output mode; 
        // comment out the line bellow to switch to 8-bit output mode 
	New |= (1 << 6);

       // } new code ends here

	if (New == Old)
		bResult = TRUE;
	else
	{
		if(WritePhysicalMemory(Address + RegisterAddress, &New, RegisterSize))
			bResult = TRUE;

	}
}

I built it in Visual Studio 2022 (a conversion to the new project format is needed; MFC will also be needed here).

This line needs to be removed before building: https://github.com/skawamoto0/ditherig/blob/2fb5b3a3b8edc405c3427757e1213cc9fcafbc9f/ditherig/stdafx.h#L21. Additionally, you need to copy all the DLLs from the project folders (InpOut32, WinRing0) into the folder where the compiled binary will be.

I would like to experiment with my 8 to 11-generation Intel laptops.

I only have a 12th generation CPU for a laptop, so I can't test it on earlier versions. However, according to the comment in the i915 module code, this will only work starting from the 12th generation (ADLP+).

amd cards will generally do 6 bit with displayport fyi.

WhisperingWind Address + RegisterAddress, &New, RegisterSize

WhisperingWind, maybe you can help with my stuck?

I am tryied to hardcode this part to Address + 0x00070030, &Old, 0x4 it works, but when I set 0x3C000000 + 0x00070030, &Old, 0x4 it didnt.

Address = ((DWORD_PTR)BAR1 | ((DWORD_PTR)BAR2 << 32)) & ~((DWORD_PTR)0x10 - 1)keeping BAR1:0x3C000004 и BAR2:0x00000060

What part I am missing, why I cant hardcode address…?

So I wanted to come in here and say that I specifically bought an Intel Arc A750 Limited Edition in the hopes that it wouldn’t dither on Windows 11. Unfortunately? Even with Ditherig running, I’m still feeling that hazy fatigue feeling after 30 minutes of use as if some area behind my eyes is being pulverized. Other Windows 11 gpus/laptops or screens give me intense eye strain as if I can’t focus on the text at all but not this one. It’s a different feeling but it’s just as unusable. I’ve tried adjusting so many things and have had no luck with Windows 11 :/

simplex

The Address has been calculated incorrectly. If BAR1=0x3c000004 and BAR2=0x00000060, then the value of Address should be 0x000000603c000000.