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Precision M6800: loss of brightness control after Big Sur update to 11.3


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Hello. I have found a solution to your mentioned issue. My Precision 7530, which also has a compatible dGPU, has non-working brightness after the 11.3+ upgrade. And yes, you are right -- the cause of the problem is because 11.3+ Apple decided to change its driver stack somehow to default the brightness control to the dGPU, which does not have internal screens. So either we use solely iGPU, or we route the internal display to the dGPU and turn off the iGPU which is power consuming. Someone on reddit, however, was smart enough to find a solution right here. In this solution, the dGPU brightness control were given back to the iGPU via a smart patch. Hope that helps!

 

https://www.reddit.com/r/hackintosh/comments/nzsyqo/inspiron_15_r_se_7520_big_sur_115_beta_2_success/?ref=share&ref_source=embed&utm_content=title&utm_medium=post_embed&utm_name=d2f878a2486d45fa91e92a051f573f6b&utm_source=embedly&utm_term=nzsyqo

 

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Thanks man I appreciate it a lot for your effort to help me. Due to lost brightness back then I have decided to go back to 11.2.3.

 

Probably today I will update my machine and give a shot with a mentioned patch. I will report back how things went in my case.

 

Thanks again for all the help.

 

Regards,

Milan


 

 

 

 

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I updated to 11.4 and off course right away I lost brightness control but after I enter above mentioned patch brightness control apears🥳. Only down side is that it is not completely functional (there is always something no matter what😅). When moving slider from right to the left screen doesn't dim until the slider passes halfway. Can this be fixed?

 

Thank you in advance!

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Screenshot 2021-07-20 at 22.44.30.png

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You need to find your dGPU PCI address and add the dGPU patch to disable the dGPU brightness control that 11.3+ defaults to.

 

From what I understand, the iGPU patch is meant to force enable backlight via iGPU, and you also need to disable the default-enabled dGPU backlight.

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iirc the M6800 has a MUX which is causing this problem on 11.3+ but the MUX also works to disable the iGPU which is why these laptops are especially good for hackintoshes due to how badly macos handles most dual gpu laptops hehe. still suggest OP to check the dGPU addresses as different chip vendors might cause differences in addresses -- at least being the case for me.

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