Reading EDID data on new Apple M1 devices

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Created Nov ’20

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Can anyone provide an example (preferably in C++) of how to read the EDID data for the current display?

I can do it on an Intel based Mac, the same code does not work on the new Apple M1 devices. The Intel code looks something like:

Code Block CFMutableDictionaryRef matching = IOServiceMatching("IODisplayConnect");
io_iterator_t iter = 99;
kern_return_t err = IOServiceGetMatchingServices( kIOMasterPortDefault, matching, &iter );
io_service_t serv;
serv = IOIteratorNext( iter );
CFDictionaryRef displayInfo;
 displayInfo = IODisplayCreateInfoDictionary( serv, kIODisplayOnlyPreferredName );
( . . . )

It appears that the new Apple M1 devices have a new video architecture, so the IOServiceMatching / IOServiceGetMatchingServices on longer works.

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Answer 1

alanfromtewksbury OP

Nov ’20

So it turns out that IODisplayConnect is not supported on Apple's M1 systems.

Look for IODPDevice then iterate as needed.

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Answer 2

MaxLeb OP

Dec ’20

Did you just replace IODisplayConnect by IODPDevice and the iteration worked out of the box ?

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