Bug 98140

Summary:

External monitor connected via VGA is not recognized

Product:

DRI

Reporter:

philipp.reinkemeier

Component:

DRM/Intel

Assignee:

Intel GFX Bugs mailing list <intel-gfx-bugs>

Status:

CLOSED DUPLICATE

QA Contact:

Intel GFX Bugs mailing list <intel-gfx-bugs>

Severity:

normal

Priority:

medium

CC:

intel-gfx-bugs

Version:

unspecified

Hardware:

x86-64 (AMD64)

OS:

Linux (All)

Whiteboard:

i915 platform:

BDW

i915 features:

display/Other

Attachments:

Description	Flags
dmesg for kernel 4.6.5 with drm.debug=14	none
systemd journal for kernel 4.6.5 with drm.debug=14	none
dmesg for kernel 4.8 with drm.debug=14	none
systemd journal for kernel 4.8 with drm.debug=14	none

Description philipp.reinkemeier 2016-10-07 08:40:16 UTC

When connecting a beamer via VGA, this external monitor is not recognized. This seems to be a regression of the i915 kernel driver. I am using archlinux, if that matters. Using kernel 4.6.5 everything works as expected, but since kernel 4.7 things are broken. Also kernel version 4.8 does not work. The hardware is a lenovo laptop T450s model, which has a VGA connector and display port. Display resolution of the laptop panel is 1920x1080.

- Kernel 4.6.5, connecting via VGA to a beamer: Works and gives 1024x768 resolution.
- Kernel 4.7 or 4.8, connecting via VGA to a beamer: Does not work.
- Kernel 4.7 or 4.8, connecting via a VGA-to-display-port adapter to the beamer: Does not work.
- Kernel 4.7 or 4.8, connecting via a HDMI-to-display-port adapter to the beamer: Works and gives 1920x1080 resolution.

For the cases where the beamer is not recognized, the output of xrandr is as follows:

Screen 0: minimum 8 x 8, current 1920 x 1080, maximum 32767 x 32767
eDP1 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 310mm x 170mm
   1920x1080     60.05*+
   1400x1050     59.98  
   1600x900      60.00  
   1280x1024     60.02  
   1280x960      60.00  
   1368x768      60.00  
   1280x720      60.00  
   1024x768      60.00  
   1024x576      60.00  
   960x540       60.00  
   800x600       60.32    56.25  
   864x486       60.00  
   640x480       59.94  
   720x405       60.00  
   640x360       60.00  
DP1 disconnected (normal left inverted right x axis y axis)
DP2 disconnected (normal left inverted right x axis y axis)
HDMI1 disconnected (normal left inverted right x axis y axis)
HDMI2 disconnected (normal left inverted right x axis y axis)
VIRTUAL1 disconnected (normal left inverted right x axis y axis)

Interestingly, connecting to an ordinary monitor via the VGA port works and gives a resolution of 1680x1050.

Comment 1 philipp.reinkemeier 2016-10-07 08:41:39 UTC

Created attachment 127085 [details]
dmesg for kernel 4.6.5 with drm.debug=14

desmg with a working kernel version 4.6.5.

Comment 2 philipp.reinkemeier 2016-10-07 08:45:23 UTC

Created attachment 127086 [details]
systemd journal for kernel 4.6.5 with drm.debug=14

I booted the laptop with the VGA connector already plugged in. After booting i remove the VGA cable and plugged it in again.

Comment 3 philipp.reinkemeier 2016-10-07 08:46:51 UTC

Created attachment 127087 [details]
dmesg for kernel 4.8 with drm.debug=14

dmesg with a broken kernel version 4.8.

Comment 4 philipp.reinkemeier 2016-10-07 08:47:58 UTC

Created attachment 127088 [details]
systemd journal for kernel 4.8 with drm.debug=14

I booted the laptop with the VGA connector already plugged in. After booting i remove the VGA cable and plugged it in again.

Comment 5 Ville Syrjala 2016-10-07 08:55:21 UTC

Probably a duplicate of bug 83348.

The fix is in now, so please test
git://anongit.freedesktop.org/drm-intel drm-intel-nightly

Comment 6 philipp.reinkemeier 2016-10-07 09:48:17 UTC

Can i cherry-pick those two commits on top of kernel v4.8 release? Or are there any other commits in git://anongit.freedesktop.org/drm-intel drm-intel-nightly that those two commits depend on?

Comment 7 Ville Syrjala 2016-10-07 09:55:31 UTC

(In reply to philipp.reinkemeier from comment #6)
> Can i cherry-pick those two commits on top of kernel v4.8 release? Or are
> there any other commits in git://anongit.freedesktop.org/drm-intel
> drm-intel-nightly that those two commits depend on?

You can try :) Haven't really checked whether there were any significant changes in those areas since 4.8. Perhaps not.

Comment 8 philipp.reinkemeier 2016-11-03 05:31:33 UTC


*** This bug has been marked as a duplicate of bug 83348 ***

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