Created attachment 117209 [details] Kernel boot params drm.debug=0xe After kernel commit 06ea66b6 the display goes into sleep after loading initramfs. I did a bisect ... Tested with the attached patch .. seems this is the case. I'm using an Intel NUC D54250WYKH which has an i5-4250U CPU. The monitor is an DELL P2415Q connected via DP cable. Both seem to support DP1.2 and 4k resolution.
Created attachment 117210 [details] Kernel boot params drm.debug=0x6
Created attachment 117211 [details] [review] Patch to disable DP_LINK_BW_5_4
Created attachment 117212 [details] Kernel bisect
Enabling MST on secondary port in the display settings ( I'm not sure what that does but I've read it has some link with multiple monitors on the same cable ) seems to make everything work at 4k but only at 30Hz ( probably that's because the mst limit ). Attaching a dmesg with it.
Created attachment 117213 [details] MST Enabled boot
In case it matters: The OS is Gentoo x86_64 The kernel is 4.1.1 with gentoo patches and aufs patches on top. The bisect I attached is of vanilla kernel straight from linus git. The attached patch works ( limiting the resolution to 2560x1440 ) on my 4.1.1+gentoo+aufs kernel. The monitor is a Dell P2415Q ( http://accessories.us.dell.com/sna/productdetail.aspx?c=us&l=en&s=dhs&cs=19&sku=860-BBFF ) connected via DP to an Intel NUC D54250WYKH ( https://www-ssl.intel.com/content/www/us/en/nuc/nuc-kit-d54250wykh.html ) miniDP. The CPU is an I5-4250U. The GPU is an Intel HD 5000 with 256 ram ( shared from the main RAM probably ) d3xbucharest ~ # lspci -v -s 00:02.0 00:02.0 VGA compatible controller: Intel Corporation Haswell-ULT Integrated Graphics Controller (rev 09) (prog-if 00 [VGA controller]) Subsystem: Intel Corporation Device 2054 Flags: bus master, fast devsel, latency 0, IRQ 40 Memory at f7800000 (64-bit, non-prefetchable) [size=4M] Memory at e0000000 (64-bit, prefetchable) [size=256M] I/O ports at f000 [size=64] Expansion ROM at <unassigned> [disabled] Capabilities: [90] MSI: Enable+ Count=1/1 Maskable- 64bit- Capabilities: [d0] Power Management version 2 Capabilities: [a4] PCI Advanced Features Kernel driver in use: i915
Does this still occur? I think we've fixed some issues with the 5.4Gb handling...
Sorry, can't test anymore. Sold the NUC.
(In reply to Adrian Sandu from comment #8) > Sorry, can't test anymore. Sold the NUC. Sorry we failed to help you, closing.
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