Ice Lake questions and problems.

[m0d16l14n1]

Hello!
I have an Ice Lake laptop, "supported" one - i7 with G7 graphics. I found out that -igfxmlr and -igfxblr are working strangely. With latest one - i am not sure if i really need that, because i previously have no problems with brightness (some guys with Ice Lake had issues with dimming screens on first boot before sleep). So, that -igfxblr is not the case for, so i will just ignore that and delete boot-arg.

So, i have two questions-issues related to Ice Lake.

But with MLR i find some strange stuff. On some ig-platform-ids it won't boot at all (reboots before Apple logo appears), on some of them it will boot to black screen (the screen is just off, because i was trying to see something using flashlight, but the screen seems to be totally off). And on some ids it will actually boot, but logs are strange.

Just an example from log.
[ 46.144240]: WhateverGreen igfx: @ (DBG) MLR: [COMM] wrapReadAUX() Maximum link rate 0x00 has been set in the DPCD buffer. [ 46.144253]: WhateverGreen igfx: @ (DBG) MLR: [ICL+] wrapReadAUX() Called with port at 0xffffff937e3ab000. [ 46.144257]: WhateverGreen igfx: @ (DBG) MLR: [COMM] orgReadAUX() Routed to ICL IMP with Address = 0x400; Length = 12. [ 46.145220]: WhateverGreen igfx: @ (DBG) MLR: [ICL+] wrapReadAUX() Called with port at 0xffffff937e3ab000. [ 46.145225]: WhateverGreen igfx: @ (DBG) MLR: [COMM] orgReadAUX() Routed to ICL IMP with Address = 0x0; Length = 6. [ 46.145462]: WhateverGreen igfx: @ (DBG) MLR: [COMM] GetFBIndex() Port at 0xffffff937e3ab000; Framebuffer at 0xffffffa03f1f1000. [ 46.145468]: WhateverGreen igfx: @ (DBG) MLR: [COMM] wrapReadAUX() Will probe the maximum link rate from the table. [ 46.145472]: WhateverGreen igfx: @ (DBG) MLR: [COMM] orgReadAUX() Routed to ICL IMP with Address = 0x700; Length = 1. [ 46.145709]: WhateverGreen igfx: @ MLR: [COMM] ProbeMaxLinkRate() eDP version is less than 1.4. Aborted. [ 46.145713]: WhateverGreen igfx: @ (DBG) MLR: [COMM] wrapReadAUX() Maximum link rate 0x00 has been set in the DPCD buffer.

I also see that in log:

[ 28.679430]: WhateverGreen igfx: @ FCM: Failed to route the function hwRegsNeedUpdate. [ 28.721381]: WhateverGreen igfx: @ BSF: Failed to route the function ComputeLaneCount.

I will attach logs of WEG and Lilu, in case it might help.
Also will attach gen_debug/darwin dumper logs.

DarwinDumper_3.1.1_2021.01.14_00.39.39_MacBookAir9,1_Opencore_4D1FDA02-38C7-4A6A-9CC6-4BCCA8B30102:opencore-version DBG-066-2021-01-09_Unknown_20D5029f_b0ltun.zip
debug_27340.zip
weg+lilu.zip

The second one is about that "boot screen" glitch (i have already opened issue about that). I was just playing around AppleIntelICLLPGraphicsFramebuffer.kext and was trying to capture logs to get that issue properly. So, on boot, while screen is black (or glitching), i can see that in logs:

2021-01-11 21:45:39.12 kernel[0]: (AppleIntelICLLPGraphicsFramebuffer) [IGFB][LOG ][DISPLAY ] hwEnableUnderrunInterrupts: Enabling underrun interrupts 2021-01-11 21:45:40.12 kernel[0]: (AppleIntelICLLPGraphicsFramebuffer) [IGFB][LOG ][DISPLAY ] hwEnableUnderrunInterrupts: Enabling underrun interrupts 2021-01-11 21:45:41.60 kernel[0]: (AppleIntelICLLPGraphicsFramebuffer) [IGFB][LOG ][DISPLAY ] hwEnableUnderrunInterrupts: Enabling underrun interrupts 2021-01-11 21:45:42.66 kernel[0]: (AppleIntelICLLPGraphicsFramebuffer) [IGFB][LOG ][DISPLAY ] hwEnableUnderrunInterrupts: Enabling underrun interrupts 2021-01-11 21:45:44.16 kernel[0]: (AppleIntelICLLPGraphicsFramebuffer) [IGFB][LOG ][DISPLAY ] hwEnableUnderrunInterrupts: Enabling underrun interrupts 2021-01-11 21:45:46.48 kernel[0]: (AppleIntelICLLPGraphicsFramebuffer) [IGFB][LOG ][DISPLAY ] hwEnableUnderrunInterrupts: Enabling underrun interrupts 2021-01-11 21:45:48.28 kernel[0]: (AppleIntelICLLPGraphicsFramebuffer) [IGFB][LOG ][DISPLAY ] hwEnableUnderrunInterrupts: Enabling underrun interrupts

Also i see something similar too when i enabled HiDPi and screen is blinking if i don't put laptop on sleep-wake cycle. After that it's working with HiDPi with no issues at all.

Display Pipe Underrun occurred on pipe

That's what i found in kext itself.

AppleIntelFramebufferController::hwEnableUnderrunInterrupts
AppleIntelFramebufferController::hwDisableUnderrunInterrupts
AppleIntelFramebufferController::checkForDisablingUnderrunInterrupt

Except that i also found this:

"[IGFB][LOG ][%-10s] Underrun boot flag is set . Underruns are enabled \n", "DISPLAY"

Is it correct, that there is some "boot flag" which can enable those underruns? I am just trying to find that boot flag for testing purposing, i didn't find it myself actually.
I am not a programmer, so sorry if it looked for you stupidly. I just took kext from system, "decompiled" it and just was looking for something similar in it from my logs.

[vit9696]

Is it correct, that there is some "boot flag" which can enable those underruns? I am just trying to find that boot flag for testing purposing, i didn't find it myself actually.

It is ig boot argument parsed in __ZN31AppleIntelFramebufferController5startEP9IOService. Needs to have any of the 0x30 bits set to enable underruns.

I assume this is rather a discussion, so closing. CC @0xFireWolf

[m0d16l14n1]

Is it correct, that there is some "boot flag" which can enable those underruns? I am just trying to find that boot flag for testing purposing, i didn't find it myself actually.

It is ig boot argument parsed in __ZN31AppleIntelFramebufferController5startEP9IOService. Needs to have any of the 0x30 bits set to enable underruns.

I assume this is rather a discussion, so closing. CC @0xFireWolf

So, it should be something like ig=48 or ig=0x30? Sorry for that stupid question

[vit9696]

Correct, but I don't know if that is going to help any of your issues.

[m0d16l14n1]

Correct, but I don't know if that is going to help any of your issues.

Yep. It seems not to wok, heh. After verbose Apple logo appears and laptop is rebooting

[m0d16l14n1]

Correct, but I don't know if that is going to help any of your issues.

Seems that i used wrong way. Now it's panicking on Display pipe underrun occurred
Still thanks for that boot-arg you found, at least i test that.

panic.zip

[m0d16l14n1]

Also i see something similar too when i enabled HiDPi and screen is blinking if i don't put laptop on sleep-wake cycle. After that it's working with HiDPi with no issues at all.

@vit9696 Sorry for pinging you. Just want to share that HiDPI issues are gone after injecting all that values in iGPU path >

Blank screen on boot is still not fixed with that :(

[m0d16l14n1]

Also i see something similar too when i enabled HiDPi and screen is blinking if i don't put laptop on sleep-wake cycle. After that it's working with HiDPi with no issues at all.

@vit9696 Sorry for pinging you. Just want to share that HiDPI issues are gone after injecting all that values in iGPU path >

Blank screen on boot is still not fixed with that :(

Only AAPL,GfxYTile needed to get HiDPI working properly