820-3476 & 820-3437 stuck on progress bar with AppleCamIN

Alan.L

Member
both boards will boot to macOS if disabled AppleCameraInterface.kext
both boards will boot to macOS if I removed Camera IC (U3900) and enable AppleCameraInterface.kext

I've replaced u3900 on both boards but still stuck on AppleCamIN.

maybe original u3900 was never bad.

any suggestions? bad communication to the PCH?


 

Alan.L

Member
its booted off an external USB drive. cam works fine on another known working board in the same chassis and screen.
its a new osx, I've even made two osx. one without cam.kext out and another one with camera.kext driver.

i don't think its ME region related. but have already tried new clean me region etc.
 
Last edited:

Alan.L

Member
asd nothing came up on both units

was liquid damaged and didn't power on. so i've fixed all that. just the camera problem now.
 

piernov

Moderator
Staff member
On the 3437 it was R2042.

Before replacement :
- SYSCLK_CLK25M_CAMERA = 0.3V
- PP3V3_S5RS3RS0_SYSCLKGEN = 1.6V
- R2042 = 8 Mohms
After replacement :
- SYSCLK_CLK25M_CAMERA = 0.56V
- PP3V3_S5RS3RS0_SYSCLKGEN = 3.3V
- R2042 = 0 ohm

Now for the stuff that doesn't make sense :
- Camera was working 100% fine under Linux.
- macOS was stalling during boot towards end of progress bar then suddenly rebooting. It was booting fine albeit with camera not working if communication between PCH and camera IC was disabled (removing R2030 or removing the caps on the PCIe bus for example).
- The clock did look fine on the oscilloscope, correct frequency and proper amplitude. Just a lower duty cycle than a known good board.

As a side note, removing camera RAM didn't change the symptoms, but once R2042 was replaced it booted fine without camera RAM. Obviously camera wasn't working, but after reballing camera RAM everything works.
Prior to finding the bad R2042, multiple camera IC were tried by Alan. I tried a known good clean ME EFI and clock generator, they didn't solve the problem in this case but they could cause similar symptoms anyway.

According to Alan, with verbose mode Sierra/Mojave were freezing on :
Code:
AppleCamIn::init
AppleCamIn::probe
AppleCamIn::start
I booted Big Sur in verbose and I didn't get these messages, it was freezing at :
Code:
IOG Flags 0x3
Generation from SMC report as 2
 
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