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Dell XPS 15 (9530) - Intel HD 4600 Graphics on QHD+ built-in display - Need some help

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RehabMan said:
+1

Well done indeed.

Given that a BIOS patch/unlock was required... will make it difficult for some. For example, latest Lenovo machines require removal of the flash chip (de-solder) from the motherboard and program with hardware programmer.
Click to expand...

Well the Dell would also require a re-programmer normally, however there is an undocumented switch for the Aptio flashing which allows writing an unsigned bios (afuwinx64 bios_mod.rom /GAN)

Not all laptops will require the bios patch only the ones who are trying to drive a display of 3200x1800 which is outside of the normal Apple specifications. Maybe there is a frame buffer patch possible to make it work within the normal DVMT size setting on the Dell XPS (32 MB), however I was unable to get that working.

Even when I raised the size to 64MB (MacbookPro default) it still wasn't enough and led to very slight corruptions.

Also the bios unlock would only be needed for people who are unable to change the DVMT size / Graphics memory size in the bios by default.

However now that the reasons are known of why a QHD+ display does not work out of the box, we can maybe look into alternative (less intrusive) options.
 
RehabMan said:
+1

Well done indeed.

Given that a BIOS patch/unlock was required... will make it difficult for some. For example, latest Lenovo machines require removal of the flash chip (de-solder) from the motherboard and program with hardware programmer.
Click to expand...

Oh No, I have a Lenovo Yoga 2 13 already on order due to be delivered this Friday. Hopefully I will not need to do any major BIOS surgery on it :(
 
the-darkvoid said:
I hope we can extend the findings to other QHD laptops also.

Anyways none of this would have been possible without people like Rehabman, Pike R. Alpha & toleda though, I extensively went over their posts to understand how everything fits together.

I'll do a clean re-install of Mavericks 10.9.4 to detail all the patches required to make it work, or see if the patches can be done dynamically from Clover.
Click to expand...

Eager for the guide.
My Thinkpad New X1 Carbon with 2560x1440 met black screen after reboot, too. I'm wondering it is caused by the same problem you addressed. Hopefully the patch won't need reburn bios because I'm not skilled for that. In my bios there is a graphic option, "intel graphic memory selection", the optinal value is 256M or 512M. I asked the lenovo service what is that exactly. But they cannot reply and just told me to ignore it.
 
elfzweik said:
Eager for the guide.
My Thinkpad New X1 Carbon with 2560x1440 met black screen after reboot, too.
Click to expand...

From what I read HD4400 might not be able to do this.
In the bios I have two settings which are of importance:


  • DVMT pre-allocated size, this is the memory size the bios reserved on startup for use by the integrated graphics. My laptop has a default of 32MB which means any 32MB frame buffers work. For higher resolutions I had to change it to 64MB and now with the QHD+ even to 128MB. (Ideally 96MB would have been a possibility, but I am fine with assigning 128MB).
  • DVMT maximum size, this is the maximum memory size your integrated graphics can use.
    For me this is currently set to 256MB, which is the default setting. Changing it to "MAX" causes my display in OS X to no longer work, so I left it as-is.

If the display remains blank but your HD graphics is correctly detected, it might be that the pixel clock of the screen is too high. You can check this by getting the screen mode line with Ubuntu Live.
Anything 250+ Mhz needs a patch to work in OS X correctly.
 
elfzweik said:
Eager for the guide.
My Thinkpad New X1 Carbon with 2560x1440 met black screen after reboot, too. I'm wondering it is caused by the same problem you addressed. Hopefully the patch won't need reburn bios because I'm not skilled for that. In my bios there is a graphic option, "intel graphic memory selection", the optinal value is 256M or 512M. I asked the lenovo service what is that exactly. But they cannot reply and just told me to ignore it.
Click to expand...

2560x1440 should be supported, so you probably won't need all the patching, but will probably need a framebuffer patch to match the IGPU memory amount.

Read the information in this thread and apply it to your situation.
 
the-darkvoid said:
From what I read HD4400 might not be able to do this.
In the bios I have two settings which are of importance:


  • DVMT pre-allocated size, this is the memory size the bios reserved on startup for use by the integrated graphics. My laptop has a default of 32MB which means any 32MB frame buffers work. For higher resolutions I had to change it to 64MB and now with the QHD+ even to 128MB. (Ideally 96MB would have been a possibility, but I am fine with assigning 128MB).
  • DVMT maximum size, this is the maximum memory size your integrated graphics can use.
    For me this is currently set to 256MB, which is the default setting. Changing it to "MAX" causes my display in OS X to no longer work, so I left it as-is.

If the display remains blank but your HD graphics is correctly detected, it might be that the pixel clock of the screen is too high. You can check this by getting the screen mode line with Ubuntu Live.
Anything 250+ Mhz needs a patch to work in OS X correctly.
Click to expand...

Also congratulations to your excellent investigation on QHD+. You came so far so quickly and in a very structured and understandable way. My hope would be most of the threads would be like yours, apart from your pioneering result.

One point I didn't get, maybe because I am a graphics noob:
Why do Win8.1 / Ubuntu work flawlessly on QHD+ without any bios manipulation on my Yoga 2 Pro?
What's the painful difference with the apple drivers needing these bios parameters?
Is there still a chance to get it work by patching / DSDT-changes?
 
emueller said:
Also congratulations to your excellent investigation on QHD+. You came so far so quickly and in a very structured and understandable way. My hope would be most of the threads would be like yours, apart from your pioneering result.

One point I didn't get, maybe because I am a graphics noob:
Why do Win8.1 / Ubuntu work flawlessly on QHD+ without any bios manipulation on my Yoga 2 Pro?
What's the painful difference with the apple drivers needing these bios parameters?
Is there still a chance to get it work by patching / DSDT-changes?
Click to expand...

Apple's drivers are written for Apple's computers, not PCs.
 
Well done. Congratulations.
 
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