[Bug 97600] New: [i915] DisplayPort connection not detected on desktop system with Q45 chipset

bugzilla-daemon at freedesktop.org bugzilla-daemon at freedesktop.org
Mon Sep 5 11:17:57 UTC 2016


https://bugs.freedesktop.org/show_bug.cgi?id=97600

            Bug ID: 97600
           Summary: [i915] DisplayPort connection not detected on desktop
                    system with Q45 chipset
           Product: DRI
           Version: unspecified
          Hardware: x86-64 (AMD64)
                OS: Linux (All)
            Status: NEW
          Severity: normal
          Priority: medium
         Component: DRM/Intel
          Assignee: intel-gfx-bugs at lists.freedesktop.org
          Reporter: michael-mayer at gmx.de
        QA Contact: intel-gfx-bugs at lists.freedesktop.org
                CC: intel-gfx-bugs at lists.freedesktop.org

Created attachment 126218
  --> https://bugs.freedesktop.org/attachment.cgi?id=126218&action=edit
output of dmesg with i915.debug=14

The displayport connection on my system works fine for the BIOS messages and
with grub, but KMS does not detect the (still existing) connection. A VGA
connection to the same display works perfectly at full resolution of 1920x1200.

Deactivating KMS with i915.modeset=0 results in a working displayport
connection at a mismatched resolution of 1600x1200 and using the vesa drivers
(confirmed by unplugging the VGA cable). So I am pretty sure this is not an
hardware issue.

dmesg with i915.debug=14 shows this (full dump is attached):
[    3.368039] [drm:drm_helper_probe_single_connector_modes_merge_bits]
[CONNECTOR:38:DP-1]
[    3.368042] [drm:intel_dp_detect] [CONNECTOR:38:DP-1]
[    3.387613] [drm:intel_dp_aux_ch] dp_aux_ch timeout status 0x501500c8
[    3.392029] [drm:drm_helper_probe_single_connector_modes_merge_bits]
[CONNECTOR:38:DP-1] status updated from 3 to 2
[    3.392032] [drm:drm_helper_probe_single_connector_modes_merge_bits]
[CONNECTOR:38:DP-1] disconnected
[    3.392036] [drm:drm_setup_crtcs] 
[    3.392067] [drm:drm_enable_connectors] connector 30 enabled? yes
[    3.392070] [drm:drm_enable_connectors] connector 33 enabled? no
[    3.392072] [drm:drm_enable_connectors] connector 38 enabled? no


some time later we see this:
[   24.824069] [drm:drm_helper_probe_single_connector_modes_merge_bits]
[CONNECTOR:38:DP-1]
[   24.824072] [drm:intel_dp_detect] [CONNECTOR:38:DP-1]
[   24.842179] [drm:intel_dp_get_dpcd] DPCD: 02 02 02 02 02 02 02 02 02 02 02
02 02 02 02
[   24.842182] [drm:intel_dp_get_dpcd] Display Port TPS3 support: source no,
sink no
[   24.842185] [drm:intel_dp_print_rates] source rates: 162000, 270000
[   24.842186] ------------[ cut here ]------------
[   24.842226] WARNING: CPU: 0 PID: 2309 at
/build/linux-a2WvEb/linux-4.4.0/drivers/gpu/drm/i915/intel_dp.c:150
intel_dp_max_link_bw.isra.7+0x2d/0x50 [i915]()
[   24.842227] invalid max DP link bw val 2, using 1.62Gbps

similar blocks are repeated a few times. The DPCD data is invalid, somehow the
communication failed again.

To me it looks like the aux channel reads give an invalid result. Strangely,
the BIOS and grub are both able to communicate with the display using the very
same connection only a few seconds earlier. Maybe the readout does not work if
the connection is already established? Maybe there are different data rates for
the aux channel?

Hardware: Lenovo ThinkCentre M58
DMI: LENOVO 7359W51/LENOVO, BIOS 5CKT49AUS 05/18/2009
Core(TM)2 Duo CPU     E7300  @ 2.66GHz (family: 0x6, model: 0x17, steppi
Chipset Q45, ICH10DO
Display HP LA2405wg


System: plain Ubuntu Mate 16.04, current kernel. The problem was exactly the
same with Ubuntu 14.04 before.

$ uname -a
Linux minibox 4.4.0-36-generic #55-Ubuntu SMP Thu Aug 11 18:01:55 UTC 2016
x86_64 x86_64 x86_64 GNU/Linux

$ xrandr --verbose
Screen 0: minimum 8 x 8, current 1920 x 1200, maximum 32767 x 32767
DP1 disconnected (normal left inverted right x axis y axis)
        Identifier: 0x42
        Timestamp:  44604
        Subpixel:   unknown
        Clones:    
        CRTCs:      0 1
        Transform:  1.000000 0.000000 0.000000
                    0.000000 1.000000 0.000000
                    0.000000 0.000000 1.000000
                   filter: 
        Broadcast RGB: Automatic 
                supported: Automatic, Full, Limited 16:235
        audio: auto 
                supported: force-dvi, off, auto, on
HDMI1 disconnected (normal left inverted right x axis y axis)
        Identifier: 0x43
        Timestamp:  44604
        Subpixel:   unknown
        Clones:     VGA1
        CRTCs:      0 1
        Transform:  1.000000 0.000000 0.000000
                    0.000000 1.000000 0.000000
                    0.000000 0.000000 1.000000
                   filter: 
        aspect ratio: Automatic 
                supported: Automatic, 4:3, 16:9
        Broadcast RGB: Automatic 
                supported: Automatic, Full, Limited 16:235
        audio: auto 
                supported: force-dvi, off, auto, on
VGA1 connected primary 1920x1200+0+0 (0x47) normal (normal left inverted right
x axis y axis) 518mm x 324mm
        Identifier: 0x44
        Timestamp:  44604
        Subpixel:   unknown
        Gamma:      0.97:1.0:0.98
        Brightness: 0.98
        Clones:     HDMI1
        CRTC:       0
        CRTCs:      0 1
        Transform:  1.000000 0.000000 0.000000
                    0.000000 1.000000 0.000000
                    0.000000 0.000000 1.000000
                   filter: 
        EDID: 
                00ffffffffffff0022f04a2801010101
                0e15010468342078ee9ec5a6564b9a25
                135054210800814081809500a940b300
                d1c0010101017d4b80a072b02d4088c8
                360006442100001c000000fd00323f18
                4c14000a202020202020000000fc004c
                41323430350a202020202020000000ff
                00434e34313134304336340a20200090
  1920x1200 (0x47) 193.250MHz -HSync +VSync *current +preferred
        h: width  1920 start 2056 end 2256 total 2592 skew    0 clock  74.56KHz
        v: height 1200 start 1203 end 1209 total 1245           clock  59.88Hz
  1920x1080 (0xa4) 148.500MHz -HSync -VSync
        h: width  1920 start 2008 end 2052 total 2200 skew    0 clock  67.50KHz
        v: height 1080 start 1084 end 1089 total 1125           clock  60.00Hz
  1600x1200 (0xa5) 162.000MHz +HSync +VSync
        h: width  1600 start 1664 end 1856 total 2160 skew    0 clock  75.00KHz
        v: height 1200 start 1201 end 1204 total 1250           clock  60.00Hz
  1680x1050 (0xa6) 146.250MHz -HSync +VSync
        h: width  1680 start 1784 end 1960 total 2240 skew    0 clock  65.29KHz
        v: height 1050 start 1053 end 1059 total 1089           clock  59.95Hz
  1280x1024 (0xa7) 108.000MHz +HSync +VSync
        h: width  1280 start 1328 end 1440 total 1688 skew    0 clock  63.98KHz
        v: height 1024 start 1025 end 1028 total 1066           clock  60.02Hz
  1440x900 (0xa8) 106.500MHz -HSync +VSync
        h: width  1440 start 1520 end 1672 total 1904 skew    0 clock  55.93KHz
        v: height  900 start  903 end  909 total  934           clock  59.89Hz
  1280x960 (0xa9) 108.000MHz +HSync +VSync
        h: width  1280 start 1376 end 1488 total 1800 skew    0 clock  60.00KHz
        v: height  960 start  961 end  964 total 1000           clock  60.00Hz
  1024x768 (0xaa) 65.000MHz -HSync -VSync
        h: width  1024 start 1048 end 1184 total 1344 skew    0 clock  48.36KHz
        v: height  768 start  771 end  777 total  806           clock  60.00Hz
  800x600 (0xab) 40.000MHz +HSync +VSync
        h: width   800 start  840 end  968 total 1056 skew    0 clock  37.88KHz
        v: height  600 start  601 end  605 total  628           clock  60.32Hz
  640x480 (0xac) 25.200MHz -HSync -VSync
        h: width   640 start  656 end  752 total  800 skew    0 clock  31.50KHz
        v: height  480 start  490 end  492 total  525           clock  60.00Hz
VIRTUAL1 disconnected (normal left inverted right x axis y axis)
        Identifier: 0x45
        Timestamp:  44604
        Subpixel:   no subpixels
        Clones:    
        CRTCs:      2
        Transform:  1.000000 0.000000 0.000000
                    0.000000 1.000000 0.000000
                    0.000000 0.000000 1.000000
                   filter:

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