Brightness problems after upgrading screen from TN to IPS: Brightness only works AFTER sleep

[rupps]

I have a HP 450G4 laptop. It originally came with a (horrible) TN screen. I have mojave 10.14.6 and brightness was working 100% on the TN panel.

So I changed the TN panel for a compatible IPS panel I just bought, an AUO B156HAN01.1.

Now, the display only works at maximum brightness level. Any other level causes the screen to go black, or to flicker like every 2 seconds (that is, black screen generally with occasional PWM flickers with the content every 2 seconds).

Interestingly, after a Sleep/Wake cycle brightness works !!

I have tried a lot of things:

* Follow the guide https://www.tonymacx86.com/threads/...ontrol-using-applebacklightfixup-kext.218222/ : Even though WhateverGreen deems AppleBacklightFixUp deprecated, I found SSDT-PNLF is different to Whatevergreen. I had to manually change IGPU to GFX0 on that version. Same result.

* Used legacy AppleBacklightInjector method after disabling WhatEverGreen backlight pathing. Same result.

* Patched and injected EDID with every method I found here: With the ruby script. with edidgen.sh, with the FixEdid application ... all of them generate slightly different patched EDIDs, but none solves the issue. With most patched EDIDs computer does not sleep (wakes up in a second). With others I get artifacts on second boot stage.

* Used WhateverGreeen parameter igfxcflbklt=1 to apply backlight patches for Coffee-Lake. With them, brightness is always 100% regardless of slider. I didn't expect this to work as this is a Kaby Lake laptop, just tried it out of desperation.

* Modified WEG´s SSDT-PNLF to initialise GRAN register as suggested by the post linked by @hut2016

So I find myself reading lots of contradicting information and guides, and don´t know how to continue.


Any suggestion? Thanks in advance !

 

[hut2016]

Try the solution at https://www.tonymacx86.com/threads/dell-inspiron-7559-graphic-problem.282230/#post-1995629

 

[rupps]

Try the solution at https://www.tonymacx86.com/threads/dell-inspiron-7559-graphic-problem.282230/#post-1995629

Thank you very much for your help, looks very related to my problem, but unfortunately nothing changes. I modified the SSDT-PNLF provided by WEG, and also tried another DSL in that thread that is slightly different.

 

[hut2016]

Hi,

Several things I've noticed from your debug files:
1. GFX0 not renamed to IGPU.
2. You have device RMCF defined in SSDT-4x0G4k.aml, so RMCF.BLKT in SSDT-4x0G4k.aml is where you should change the value. Just to be sure you've done it right.

 

[rupps]

@hut2016, Thanks for taking a look to my configuration.

1. GFX0 not renamed to IGPU.

I consciously removed the rename as instructed in WEG manual, https://github.com/acidanthera/WhateverGreen/blob/master/Manual/FAQ.IntelHD.en.md point 12, and also checked out that in the rest of files, SSDT-PLNF included, there are no references to IGPU but to GFX0. I also tried to keep the rename with the same result.

2. You have device RMCF defined in SSDT-4x0G4k.aml, so RMCF.BLKT in SSDT-4x0G4k.aml is where you should change the value. Just to be sure you've done it right.

You are right! Unfortunately after changing the byte to 0x05 so GRAN gets initialized, nothing changes.

BTW - I found this thread https://www.tonymacx86.com/threads/brightness-controls-works-only-after-sleep.256241/ where Rehabman and yourself help a user with exactly the same issue. I installed ACPIDEBUG and added traces to SSDT-PNLF but unfortunately I also run into the same problem where registers show 0xffff even after just storing a value to them. Is this approach interesting?

kernel: (ACPIDebug) ACPIDebug: { "_INI Local4:", 0x5, }
kernel: (ACPIDebug) ACPIDebug: { "_INI GDID:", 0x5916,
kernel: (ACPIDebug) ACPIDebug: { "INI1", 0x5, }
kernel: (ACPIDebug) ACPIDebug: { "INI1 STGRAN", 0x0, }
kernel: (ACPIDebug) ACPIDebug: { "INI1 GRAN STORED", 0xffffffff, } // WTF !! SHOULD BE 0 !!
kernel: (ACPIDebug) ACPIDebug: { "Local2:", 0x56c, }
kernel: (ACPIDebug) ACPIDebug: { "LEVX:", 0xffffffff, }
kernel: (ACPIDebug) ACPIDebug: { "LEVW:", 0xffffffff, }
kernel: (ACPIDebug) ACPIDebug: { "LEVL:", 0xffffffff, }
kernel: (ACPIDebug) ACPIDebug: { "LEV2:", 0xffffffff, }
kernel: (ACPIDebug) ACPIDebug: { "P0BL:", 0xffffffff, }
kernel: (ACPIDebug) ACPIDebug: { "PCHL:", 0xffffffff, }
kernel: (ACPIDebug) ACPIDebug: { "GRAN:", 0xffffffff, }

Also found https://www.tonymacx86.com/threads/...ra-high-sierra-mojave-install.201576/page-101 about this, and tried your SSDT-PNLF (same result)

So do you think is there any chance this can get fixed or I better trigger a script with a sleep-wake on computer boot, or disable brightness and forget about all this?