Display ports?

[Amethyst1]

I wonder if the EDID seen by the 2007 MacBook Pro matches the EDID seen by the iMac?

Yup. See attached files.

 

[joevt]

Yup. See attached files.

That EDID is from the override file
/System/Library/Displays/Contents/Resources/Overrides/DisplayVendorID-610/DisplayProductID-9cb5
I think we need AGDCDiagnose to get the real EDID (or the EDID that a PC would see).
It would be interesting to see why Apple decided on using an override.

 

[Amethyst1]

It would be interesting to see why Apple decided on using an override.

To add (scaled) resolutions lower than 2560×1440 perhaps?

I think we need AGDCDiagnose to get the real EDID (or the EDID that a PC would see).

I can hook up the 2010 iMac in Target Display Mode to the RX 460 and provide its output.

Its output on the 2010 iMac itself (HD 4850, High Sierra) is very brief. Would it still be of use?

 

[joevt]

To add (scaled) resolutions lower than 2560×1440 perhaps?

It does do that:
640x480 {00000002}
800x600 {00000002}
1024x768 {00000001}
1280x1024 {00000001}
1344x756 {00000002}
1600x900 {00000002}
1680x1050 {00000002}
1920x1080 {00000002}
1600x1200 {00000002}
1920x1200 {00000002}
but an EDID override is separate from the scaled modes. There's a lot of color and gamma stuff in the file. The file has a product name override "iMac".

Its output on the 2010 iMac itself (HD 4850, High Sierra) is very brief. Would it still be of use?

Only if it included an EDID section. If it doesn't include EDID, then I guess it's useful to know what it does include.

 

[Amethyst1]

@joevt

Attached is the 27" 2010 iMac's EDID in Target Display Mode from AGDCDiagnose via the RX 460, and the EDID as read by SwitchResX on the iMac itself after deleting the override file.

 

[joevt]

@joevt

Attached is the 27" 2010 iMac's EDID in Target Display Mode from AGDCDiagnose via the RX 460, and the EDID as read by SwitchResX on the iMac itself after deleting the override file.

Those two match (AGDiagnose and SwitchResX without override).
It seems the override in your previous post just removes a 1280x720 mode (a quarter of the native 2560x1440 mode).
1280x720@59.855Hz 44.772kHz 74.50MHz h(64 128 192 -) v(3 5 20 +)
Question: does the display support this timing? Does the display support any other timings?

I know for my Apple 30" Cinema Display, it only supports 2560x1600 (dual link DVI) and 1280x800 (single link DVI) and it doesn't use any interpolation for scaling up the 1280x800 - it just quadruples each pixel. So you can see a difference between the 1280x800 timing (scaled up by the display - it's blocky) and a 1280x800 scaled mode (scaled up by the GPU - it's smooth).

My Acer XV273K can take any timing (between 24Hz and 144Hz from 342x192 to 8K) and uses interpolation for scaling.

 

[Amethyst1]

1280x720@59.855Hz 44.772kHz 74.50MHz h(64 128 192 -) v(3 5 20 +)
Question: does the display support this timing?

Yep.

Does the display support any other timings?

I tried various 16:9 60 Hz CVT-RB timings from 1024×576 to 2304×1296 - all of them produce a black screen.
2560×1440 at 41 Hz works but displays "waves" of moving pixels throughout the screen. 2560×1440 at 48 Hz also displays anomalies.

I know for my Apple 30" Cinema Display, it only supports 2560x1600 (dual link DVI) and 1280x800 (single link DVI) and it doesn't use any interpolation for scaling up the 1280x800 - it just quadruples each pixel. So you can see a difference between the 1280x800 timing (scaled up by the display - it's blocky) and a 1280x800 scaled mode (scaled up by the GPU - it's smooth).

The iMac's display is the same - 1280×720 scaled up by itself is blocky, but if done by the GPU it's smooth.