[Help] Dell Broadwell HD5500 4K can't get full resolution

[PacMan]

Hi, I have this 4K buit-in display and I'm not being able to reach the 3840x2160 resolution nor 1920x1080 HiDPI. The display works up to 3360x1890 (non HiDPI), and scaled to 1680x945 (HiDPI), but any resolution higher than that gives me a black screen with backlight.

I've changed the BIOS to 128MB (also tried 64 and 96 with no change), and patched the framebuffer to 48/48 (as for the XPS 9350) with no luck.
Also tried different ig-platform values such as:

• 0x16060002
• 0x16160002
• 0x16220002
• 0x16260002
• 0x16260004
• 0x16260005
• 0x16260006
• 0x162B0002
• 0x162B0004

Did anyone get the 4K display working at full resolution with this graphic card? Don't know what else to try, if anyone has patched the framebuffer somehow on Broadwell to get 4K working please help me.

Thanks in advance, any tip is appreciated.

PS: I patched brightness, battery status, USB, PM, but I don't seem to figure this one out. Also, I followed RehabMan's guide so WhateverGreen and Lilu are installed with -cdfon as boot argument.

 

[RehabMan]

Hi, I have this 4K buit-in display and I'm not being able to reach the 3840x2160 resolution nor 1920x1080 HiDPI. The display works up to 3360x1890 (non HiDPI), and scaled to 1680x945 (HiDPI), but any resolution higher than that gives me a black screen with backlight.

I've changed the BIOS to 128MB (also tried 64 and 96 with no change), and patched the framebuffer to 48/48 (as for the XPS 9350) with no luck.
Also tried different ig-platform values such as:

• 0x16060002
• 0x16160002
• 0x16220002
• 0x16260002
• 0x16260004
• 0x16260005
• 0x16260006
• 0x162B0002
• 0x162B0004

Did anyone get the 4K display working at full resolution with this graphic card? Don't know what else to try, if anyone has patched the framebuffer somehow on Broadwell to get 4K working please help me.

Thanks in advance, any tip is appreciated.

PS: I patched brightness, battery status, USB, PM, but I don't seem to figure this one out. Also, I followed RehabMan's guide so WhateverGreen and Lilu are installed with -cdfon as boot argument.

No ioreg in the attached debug zip. Please check your files carefully before upload.

 

[PacMan]

No ioreg in the attached debug zip. Please check your files carefully before upload.

My bad, complete debug files attached.

 

[PacMan]

I tried injecting different EDID but didn't fix the problem. Still can't figure it out.
Any ides out there?

 

[RehabMan]

My bad, complete debug files attached.

Did you try a lower refresh rate (than 60Hz)?

 

[PacMan]

Did you try a lower refresh rate (than 60Hz)?

I tried 48 Hz (with SwitchRes) with no change at all.
I checked if there was any change on the refresh rate on terminal with

system_profiler SPDisplaysDataType

and shows 48Hz, but screen still not working.

 

[RehabMan]

I tried 48 Hz (with SwitchRes) with no change at all.
I checked if there was any change on the refresh rate on terminal with

system_profiler SPDisplaysDataType

and shows 48Hz, but screen still not working.

Try different ig-platform-id values.

 

[PacMan]

Try different ig-platform-id values.

I tried with all this platform-id values (they are all the Broadwell mobile ones) with no change

• 0x16060002
• 0x16160002
• 0x16220002
• 0x16260002
• 0x16260004
• 0x16260005
• 0x16260006
• 0x162B0002
• 0x162B0004

 

[RehabMan]

I tried with all this platform-id values (they are all the Broadwell mobile ones) with no change

No other ideas for you.

 

[PacMan]

No other ideas for you.

Thanks for your time @RehabMan, one last question, on About this Mac it says the display is 15,5 inch but it's actually a 15,6 inch screen, this could be the actual problem or its not related?
If it is, don't know how to make macOS to read proper screen size.



Note: it happened also with the external monitor, it showed 54,5 inch when is a 55 inch TV.