How does xorg decide which resolutions to show from EDID? Newer versions stopped offering 4K 3840x2160
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Starting sometime last year, forcing the 2160p resolution manually became necessary, with reduced vertical blanking. Standard Haswell notebook setup.
So, this particular installation is regularly hooked up to various 4K Big screen TVs. Until the last kernel-update the user could select 3840x2160@30 from the GUI settings applet. (xrandr said iirc 29.98)
Currently, this machine runs a Debian 4.9.65-3 kernel, on an "Intel Haswell-ULT Integrated Graphics Controller" (8086:0a16), Display Server: X.Org 1.16.4, driver: intel.
Now, in order to display 4K, a mode with reduced vertical blanking is needed to be inserted manually via xrandr, bound to HDMI2, and activated.
Attempting to use a mode without reduced vertical blanking led to an error like Configure crtc 1 failed. This is on 3 different 40"ish screens.
I found this unanswered similar-sounding question from >4y ago, where his xrandr would output a bunch of totally bonkers resolutions for a 2560x1440 panel.
I also saw this question, and the great AA from @StephenKitt, which helped greatly for the workaround above.
So what is going on? Where is this change coming from? Why was it stopped being offered?
xorg xrandr monitors edid
asked Feb 1 at 20:32
Alex Stragies
3,1291436
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Starting sometime last year, forcing the 2160p resolution manually became necessary, with reduced vertical blanking. Standard Haswell notebook setup.
So, this particular installation is regularly hooked up to various 4K Big screen TVs. Until the last kernel-update the user could select 3840x2160@30 from the GUI settings applet. (xrandr said iirc 29.98)
Currently, this machine runs a Debian 4.9.65-3 kernel, on an "Intel Haswell-ULT Integrated Graphics Controller" (8086:0a16), Display Server: X.Org 1.16.4, driver: intel.
Now, in order to display 4K, a mode with reduced vertical blanking is needed to be inserted manually via xrandr, bound to HDMI2, and activated.
Attempting to use a mode without reduced vertical blanking led to an error like Configure crtc 1 failed. This is on 3 different 40"ish screens.
I found this unanswered similar-sounding question from >4y ago, where his xrandr would output a bunch of totally bonkers resolutions for a 2560x1440 panel.
I also saw this question, and the great AA from @StephenKitt, which helped greatly for the workaround above.
So what is going on? Where is this change coming from? Why was it stopped being offered?
xorg xrandr monitors edid
asked Feb 1 at 20:32
Alex Stragies
3,1291436
1
The X driver checks all modes and throws out modes that it thinks won't work. Looks like somebody had issues with the mode without reduced vertical blanking, so the developers made filtering more strict. If you really want to find out, identify the exact driver you are using, identify the versions before and after the change took place, and look it up in the source code. The commit message for the change will likely give the reason.
– dirkt
Feb 3 at 20:19
add a comment |Â
up vote
0
down vote
favorite
up vote
0
down vote
favorite
Starting sometime last year, forcing the 2160p resolution manually became necessary, with reduced vertical blanking. Standard Haswell notebook setup.
So, this particular installation is regularly hooked up to various 4K Big screen TVs. Until the last kernel-update the user could select 3840x2160@30 from the GUI settings applet. (xrandr said iirc 29.98)
Currently, this machine runs a Debian 4.9.65-3 kernel, on an "Intel Haswell-ULT Integrated Graphics Controller" (8086:0a16), Display Server: X.Org 1.16.4, driver: intel.
Now, in order to display 4K, a mode with reduced vertical blanking is needed to be inserted manually via xrandr, bound to HDMI2, and activated.
Attempting to use a mode without reduced vertical blanking led to an error like Configure crtc 1 failed. This is on 3 different 40"ish screens.
I found this unanswered similar-sounding question from >4y ago, where his xrandr would output a bunch of totally bonkers resolutions for a 2560x1440 panel.
I also saw this question, and the great AA from @StephenKitt, which helped greatly for the workaround above.
So what is going on? Where is this change coming from? Why was it stopped being offered?
xorg xrandr monitors edid
asked Feb 1 at 20:32
Alex Stragies
3,1291436
Starting sometime last year, forcing the 2160p resolution manually became necessary, with reduced vertical blanking. Standard Haswell notebook setup.
So, this particular installation is regularly hooked up to various 4K Big screen TVs. Until the last kernel-update the user could select 3840x2160@30 from the GUI settings applet. (xrandr said iirc 29.98)
Currently, this machine runs a Debian 4.9.65-3 kernel, on an "Intel Haswell-ULT Integrated Graphics Controller" (8086:0a16), Display Server: X.Org 1.16.4, driver: intel.
Now, in order to display 4K, a mode with reduced vertical blanking is needed to be inserted manually via xrandr, bound to HDMI2, and activated.
Attempting to use a mode without reduced vertical blanking led to an error like Configure crtc 1 failed. This is on 3 different 40"ish screens.
I found this unanswered similar-sounding question from >4y ago, where his xrandr would output a bunch of totally bonkers resolutions for a 2560x1440 panel.
I also saw this question, and the great AA from @StephenKitt, which helped greatly for the workaround above.
So what is going on? Where is this change coming from? Why was it stopped being offered?
xorg xrandr monitors edid
asked Feb 1 at 20:32
Alex Stragies
3,1291436
edited Feb 1 at 21:00
asked Feb 1 at 20:32
Alex Stragies
3,1291436
asked Feb 1 at 20:32
Alex Stragies
3,1291436
asked Feb 1 at 20:32
Alex Stragies
3,1291436
3,1291436
1
The X driver checks all modes and throws out modes that it thinks won't work. Looks like somebody had issues with the mode without reduced vertical blanking, so the developers made filtering more strict. If you really want to find out, identify the exact driver you are using, identify the versions before and after the change took place, and look it up in the source code. The commit message for the change will likely give the reason.
– dirkt
Feb 3 at 20:19
add a comment |Â
1
The X driver checks all modes and throws out modes that it thinks won't work. Looks like somebody had issues with the mode without reduced vertical blanking, so the developers made filtering more strict. If you really want to find out, identify the exact driver you are using, identify the versions before and after the change took place, and look it up in the source code. The commit message for the change will likely give the reason.
– dirkt
Feb 3 at 20:19
1
1
The X driver checks all modes and throws out modes that it thinks won't work. Looks like somebody had issues with the mode without reduced vertical blanking, so the developers made filtering more strict. If you really want to find out, identify the exact driver you are using, identify the versions before and after the change took place, and look it up in the source code. The commit message for the change will likely give the reason.
– dirkt
Feb 3 at 20:19
The X driver checks all modes and throws out modes that it thinks won't work. Looks like somebody had issues with the mode without reduced vertical blanking, so the developers made filtering more strict. If you really want to find out, identify the exact driver you are using, identify the versions before and after the change took place, and look it up in the source code. The commit message for the change will likely give the reason.
– dirkt
Feb 3 at 20:19
add a comment |Â
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1
The X driver checks all modes and throws out modes that it thinks won't work. Looks like somebody had issues with the mode without reduced vertical blanking, so the developers made filtering more strict. If you really want to find out, identify the exact driver you are using, identify the versions before and after the change took place, and look it up in the source code. The commit message for the change will likely give the reason.
– dirkt
Feb 3 at 20:19