I have a Philips Brilliance 288P monitor, which should support 3840x2160 @ 60Hz through DisplayPort. My computer is a Lenovo ThinkPad T550 with Intel HD Graphics 5500, which also should support this resolution and refresh rate. However, only 30Hz mode works - If I switch the display to 60hz (or when it tries this setting automatically during login) I just see weird grey lines on half of the screen, other half is black (Screenshot - https://www.dropbox.com/s/1toa4v4clxg71jf/2015-04-13%2012.04.04.jpg?dl=0 ) xrandr reports both refresh rates: DP1 connected 3840x2160+2880+0 (normal left inverted right x axis y axis) 621mm x 341mm 3840x2160 60.00 + 30.00* I'm running kernel 4.0.0-rc7-drm_intel_nightly_20150411 (on 3.19 or mainline 4.0-rc7 kernel the system locks up on entering this refresh rate) with parameter i915.enable_ips=0 Monitor DisplayPort mode is set to 1.2.
Your monitor is not a true 3840x2160 @ 60Hz but is a composite of a pair of panels (or sometimes more). In order to drive that high frequency mode you need to use MST.
I think there is still some kind of a bug, because when I try to enable monitor in displayport 1.2 mode I don't get two DP devices, it just goes blank, and I get [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe B FIFO underrun errors. This must be not xf86-video-intel related, but where should I report it?
@Marat, have you managed to solve this problem? I'm having a similar issue with a Lenovo ThinkPad X240 (Intel HD Graphics 4400) connected via DisplayPort to a Dell P2415Q monitor. The 3840x2160 30MHz and 35MHz modes work fine, but 60MHz gives a blank screen (so it's a little bit different than yours) and dmesg reports: [ 3235.577003] [drm:intel_set_cpu_fifo_underrun_reporting [i915]] *ERROR* uncleared fifo underrun on pipe B [ 3235.577018] [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe B FIFO underrun Running Kernel 4.0.4-2-ARCH #1 x86_64 (Arch Linux), but can try some version from the Intel branch if that helps.
(In reply to Tiago Madeira from comment #3) > @Marat, have you managed to solve this problem? > No, more details in this bug https://bugs.freedesktop.org/show_bug.cgi?id=90043
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