[Bug 90609] Kernel crash when using DisplayPort MST on W740SU with Dell U2414H

Sat May 23 22:25:35 PDT 2015

https://bugs.freedesktop.org/show_bug.cgi?id=90609

--- Comment #4 from Ricardo Salveti de Araujo <rsalveti at gmail.com> ---
Kernel crashes while iterating the crtc_list (when setting the crtc_config).

(gdb) list *(drm_crtc_index+0x5)
0xfa5 is in drm_crtc_index
(/home/rsalveti/projects/kernel/linux-2.6/drivers/gpu/drm/drm_crtc.c:738).
733    unsigned int drm_crtc_index(struct drm_crtc *crtc)
734    {
735        unsigned int index = 0;
736        struct drm_crtc *tmp;
737    
738        list_for_each_entry(tmp, &crtc->dev->mode_config.crtc_list, head) {
739            if (tmp == crtc)
740                return index;
741    
742            index++;

One weird thing that I noticed is that the list of modes when using MST is
different, when using the same monitor.

With MST:
[   57.305582] [drm:drm_helper_probe_single_connector_modes_merge_bits]
[CONNECTOR:49:DP-2] probed modes :
[   57.305585] [drm:drm_mode_debug_printmodeline] Modeline 60:"1024x768" 60
65000 1024 1048 1184 1344 768 771 777 806 0x40 0xa
[   57.305588] [drm:drm_mode_debug_printmodeline] Modeline 58:"800x600" 60
40000 800 840 968 1056 600 601 605 628 0x40 0x5
[   57.305590] [drm:drm_mode_debug_printmodeline] Modeline 57:"800x600" 56
36000 800 824 896 1024 600 601 603 625 0x40 0x5
[   57.305592] [drm:drm_mode_debug_printmodeline] Modeline 59:"848x480" 60
33750 848 864 976 1088 480 486 494 517 0x40 0x5
[   57.305594] [drm:drm_mode_debug_printmodeline] Modeline 52:"640x480" 60
25175 640 656 752 800 480 490 492 525 0x40 0xa

Without MST (displayport 1.2 disabled):
[   45.793283] [drm:drm_helper_probe_single_connector_modes_merge_bits]
[CONNECTOR:41:DP-1] probed modes :
[   45.793285] [drm:drm_mode_debug_printmodeline] Modeline 51:"1920x1080" 60
148500 1920 2008 2052 2200 1080 1084 1089 1125 0x48 0x5
[   45.793287] [drm:drm_mode_debug_printmodeline] Modeline 80:"1920x1080" 60
148352 1920 2008 2052 2200 1080 1084 1089 1125 0x40 0x5
[   45.793288] [drm:drm_mode_debug_printmodeline] Modeline 53:"1920x1080i" 60
74250 1920 2008 2052 2200 1080 1084 1094 1125 0x40 0x15
[   45.793290] [drm:drm_mode_debug_printmodeline] Modeline 82:"1920x1080i" 60
74176 1920 2008 2052 2200 1080 1084 1094 1125 0x40 0x15
[   45.793291] [drm:drm_mode_debug_printmodeline] Modeline 77:"1920x1080" 50
148500 1920 2448 2492 2640 1080 1084 1089 1125 0x40 0x5
[   45.793292] [drm:drm_mode_debug_printmodeline] Modeline 76:"1920x1080i" 50
74250 1920 2448 2492 2640 1080 1084 1094 1125 0x40 0x15
[   45.793294] [drm:drm_mode_debug_printmodeline] Modeline 98:"1600x1200" 60
162000 1600 1664 1856 2160 1200 1201 1204 1250 0x40 0x5
[   45.793296] [drm:drm_mode_debug_printmodeline] Modeline 58:"1600x900" 60
108000 1600 1624 1704 1800 900 901 904 1000 0x40 0x5 
[   45.793297] [drm:drm_mode_debug_printmodeline] Modeline 64:"1280x1024" 75
135000 1280 1296 1440 1688 1024 1025 1028 1066 0x40 0x5
[   45.793299] [drm:drm_mode_debug_printmodeline] Modeline 57:"1280x1024" 60
108000 1280 1328 1440 1688 1024 1025 1028 1066 0x40 0x5
[   45.793300] [drm:drm_mode_debug_printmodeline] Modeline 56:"1152x864" 75
108000 1152 1216 1344 1600 864 865 868 900 0x40 0x5
[   45.793302] [drm:drm_mode_debug_printmodeline] Modeline 54:"1280x720" 60
74250 1280 1390 1430 1650 720 725 730 750 0x40 0x5
[   45.793303] [drm:drm_mode_debug_printmodeline] Modeline 83:"1280x720" 60
74176 1280 1390 1430 1650 720 725 730 750 0x40 0x5
[   45.793305] [drm:drm_mode_debug_printmodeline] Modeline 79:"1280x720" 50
74250 1280 1720 1760 1980 720 725 730 750 0x40 0x5
[   45.793306] [drm:drm_mode_debug_printmodeline] Modeline 65:"1024x768" 75
78800 1024 1040 1136 1312 768 769 772 800 0x40 0x5
[   45.793308] [drm:drm_mode_debug_printmodeline] Modeline 66:"1024x768" 60
65000 1024 1048 1184 1344 768 771 777 806 0x40 0xa
[   45.793309] [drm:drm_mode_debug_printmodeline] Modeline 67:"800x600" 75
49500 800 816 896 1056 600 601 604 625 0x40 0x5
[   45.793311] [drm:drm_mode_debug_printmodeline] Modeline 60:"800x600" 60
40000 800 840 968 1056 600 601 605 628 0x40 0x5
[   45.793312] [drm:drm_mode_debug_printmodeline] Modeline 78:"720x576" 50
27000 720 732 796 864 576 581 586 625 0x40 0xa
[   45.793313] [drm:drm_mode_debug_printmodeline] Modeline 84:"720x480" 60
27027 720 736 798 858 480 489 495 525 0x40 0xa
[   45.793315] [drm:drm_mode_debug_printmodeline] Modeline 55:"720x480" 60
27000 720 736 798 858 480 489 495 525 0x40 0xa
[   45.793316] [drm:drm_mode_debug_printmodeline] Modeline 61:"640x480" 75
31500 640 656 720 840 480 481 484 500 0x40 0xa
[   45.793318] [drm:drm_mode_debug_printmodeline] Modeline 62:"640x480" 60
25200 640 656 752 800 480 490 492 525 0x40 0xa
[   45.793319] [drm:drm_mode_debug_printmodeline] Modeline 75:"640x480" 60
25175 640 656 752 800 480 490 492 525 0x40 0xa
[   45.793320] [drm:drm_mode_debug_printmodeline] Modeline 63:"720x400" 70
28320 720 738 846 900 400 412 414 449 0x40 0x6

Monitor works fine when MST is enabled at the bios/boot loader screen (using
1920x1080). It only gets broken after linux boots.

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