[Intel-gfx] UHD 620: How to debug a screen resolution that does not work reliably

Ricardo Ribalda Delgado ricardo.ribalda at gmail.com
Mon Apr 23 21:56:00 UTC 2018 

Hi

I have a secondary monitor connected via USB-C adapter to  HDMI. It
can manage resolutions up to 2560x1440.

Most of the time, when the system is booted the resolution is detected
ok, but If I suspend the machine, or replug the screen, or alternate
to the text console, the resolution is "downgraded" to Full HD.

I have added the paramter drm.debug=0x06  to my kernel option and I
have managed to catch this error when the resolution is not detected
properly:

[    4.941022] [drm:drm_mode_debug_printmodeline [drm]] Modeline
77:"2560x1440" 60 241500 2560 2608 2640 2720 1440 1443 1448 1481 0x48
0x5
[    4.941046] [drm:drm_mode_prune_invalid [drm]] Not using 2560x1440
mode: CLOCK_HIGH


On the other hand, when it works fine:

[   95.361838] [drm:drm_mode_debug_printmodeline [drm]] Modeline
85:"2560x1440" 60 241500 2560 2608 2640 2720 1440 1443 1448 1481 0x48
0x5
[   95.928536] [drm:intel_dump_pipe_config [i915]] crtc timings:
241500 2560 2608 2640 2720 1440 1443 1448 1481, type: 0x48 flags: 0x5
[   95.928546] [drm:intel_dump_pipe_config [i915]] port clock: 540000,
pipe src size: 2560x1440, pixel rate 241500


The adapter is brand new (Xiaomi) and the cable should be of good
quality (ethernet capable).


Any ideas about how to debug this? The EDID seems fine, it seems
related to hock clock_high is calculated.


My kernel version is Linux piling 4.15.0-2-amd64 #1 SMP Debian
4.15.11-1 (2018-03-20) x86_64 GNU/Linux

When it works:
[  853.586182] [drm:drm_detect_monitor_audio [drm]] Monitor has basic
audio support
[  853.586850] [drm:intel_power_well_disable [i915]] disabling power well 2
[  853.586862] [drm:drm_add_display_info [drm]] non_desktop set to 0
[  853.586868] [drm:drm_add_display_info [drm]] HDMI: DVI dual 0, max
TMDS clock 300000 kHz
[  853.586874] [drm:drm_add_display_info [drm]] non_desktop set to 0
[  853.586879] [drm:drm_add_display_info [drm]] HDMI: DVI dual 0, max
TMDS clock 300000 kHz
[  853.586956] [drm:drm_edid_to_eld [drm]] ELD monitor Q2775
[  853.586961] [drm:drm_edid_to_eld [drm]] HDMI: latency present 0 0,
video latency 0 0, audio latency 0 0
[  853.586974] [drm:intel_connector_update_modes [i915]] ELD size 28,
SAD count 1
[  853.587047] [drm:drm_helper_probe_single_connector_modes
[drm_kms_helper]] [CONNECTOR:69:DP-1] probed modes :
[  853.587054] [drm:drm_mode_debug_printmodeline [drm]] Modeline
84:"2560x1440" 60 241500 2560 2608 2640 2720 1440 1443 1448 1481 0x48
0x5
[  853.587059] [drm:drm_mode_debug_printmodeline [drm]] Modeline
87:"1920x1080" 60 148500 1920 2008 2052 2200 1080 1084 1089 1125 0x40
0x5
[  853.587064] [drm:drm_mode_debug_printmodeline [drm]] Modeline
123:"1920x1080" 60 148352 1920 2008 2052 2200 1080 1084 1089 1125 0x40
0x5
[  853.587069] [drm:drm_mode_debug_printmodeline [drm]] Modeline
114:"1920x1080i" 60 74250 1920 2008 2052 2200 1080 1084 1094 1125 0x40
0x15
[  853.587073] [drm:drm_mode_debug_printmodeline [drm]] Modeline
128:"1920x1080i" 60 74176 1920 2008 2052 2200 1080 1084 1094 1125 0x40
0x15
[  853.587078] [drm:drm_mode_debug_printmodeline [drm]] Modeline
113:"1920x1080" 50 148500 1920 2448 2492 2640 1080 1084 1089 1125 0x40
0x5
[  853.587082] [drm:drm_mode_debug_printmodeline [drm]] Modeline
115:"1920x1080i" 50 74250 1920 2448 2492 2640 1080 1084 1094 1125 0x40
0x15
[  853.587087] [drm:drm_mode_debug_printmodeline [drm]] Modeline
91:"1280x1440" 60 156000 1280 1376 1512 1744 1440 1443 1453 1493 0x40
0x6
[  853.587091] [drm:drm_mode_debug_printmodeline [drm]] Modeline
92:"1680x1050" 60 119000 1680 1728 1760 1840 1050 1053 1059 1080 0x40
0x9
[  853.587095] [drm:drm_mode_debug_printmodeline [drm]] Modeline
103:"1280x1024" 75 135000 1280 1296 1440 1688 1024 1025 1028 1066 0x40
0x5
[  853.587099] [drm:drm_mode_debug_printmodeline [drm]] Modeline
94:"1280x1024" 60 108000 1280 1328 1440 1688 1024 1025 1028 1066 0x40
0x5
[  853.587104] [drm:drm_mode_debug_printmodeline [drm]] Modeline
93:"1440x900" 60 88750 1440 1488 1520 1600 900 903 909 926 0x40 0x9
[  853.587108] [drm:drm_mode_debug_printmodeline [drm]] Modeline
95:"1280x960" 60 108000 1280 1376 1488 1800 960 961 964 1000 0x40 0x5
[  853.587112] [drm:drm_mode_debug_printmodeline [drm]] Modeline
88:"1280x720" 60 74250 1280 1390 1430 1650 720 725 730 750 0x40 0x5
[  853.587116] [drm:drm_mode_debug_printmodeline [drm]] Modeline
124:"1280x720" 60 74176 1280 1390 1430 1650 720 725 730 750 0x40 0x5
[  853.587121] [drm:drm_mode_debug_printmodeline [drm]] Modeline
117:"1280x720" 50 74250 1280 1720 1760 1980 720 725 730 750 0x40 0x5
[  853.587125] [drm:drm_mode_debug_printmodeline [drm]] Modeline
104:"1024x768" 75 78750 1024 1040 1136 1312 768 769 772 800 0x40 0x5
[  853.587129] [drm:drm_mode_debug_printmodeline [drm]] Modeline
105:"1024x768" 70 75000 1024 1048 1184 1328 768 771 777 806 0x40 0xa
[  853.587133] [drm:drm_mode_debug_printmodeline [drm]] Modeline
106:"1024x768" 60 65000 1024 1048 1184 1344 768 771 777 806 0x40 0xa
[  853.587137] [drm:drm_mode_debug_printmodeline [drm]] Modeline
107:"832x624" 75 57284 832 864 928 1152 624 625 628 667 0x40 0xa
[  853.587142] [drm:drm_mode_debug_printmodeline [drm]] Modeline
108:"800x600" 75 49500 800 816 896 1056 600 601 604 625 0x40 0x5
[  853.587146] [drm:drm_mode_debug_printmodeline [drm]] Modeline
110:"800x600" 72 50000 800 856 976 1040 600 637 643 666 0x40 0x5
[  853.587150] [drm:drm_mode_debug_printmodeline [drm]] Modeline
96:"800x600" 60 40000 800 840 968 1056 600 601 605 628 0x40 0x5
[  853.587154] [drm:drm_mode_debug_printmodeline [drm]] Modeline
97:"800x600" 56 36000 800 824 896 1024 600 601 603 625 0x40 0x5
[  853.587158] [drm:drm_mode_debug_printmodeline [drm]] Modeline
90:"720x576" 50 27000 720 732 796 864 576 581 586 625 0x40 0xa
[  853.587163] [drm:drm_mode_debug_printmodeline [drm]] Modeline
125:"720x480" 60 27027 720 736 798 858 480 489 495 525 0x40 0xa
[  853.587167] [drm:drm_mode_debug_printmodeline [drm]] Modeline
89:"720x480" 60 27000 720 736 798 858 480 489 495 525 0x40 0xa
[  853.587171] [drm:drm_mode_debug_printmodeline [drm]] Modeline
98:"640x480" 75 31500 640 656 720 840 480 481 484 500 0x40 0xa
[  853.587175] [drm:drm_mode_debug_printmodeline [drm]] Modeline
99:"640x480" 73 31500 640 664 704 832 480 489 492 520 0x40 0xa
[  853.587180] [drm:drm_mode_debug_printmodeline [drm]] Modeline
100:"640x480" 67 30240 640 704 768 864 480 483 486 525 0x40 0xa
[  853.587184] [drm:drm_mode_debug_printmodeline [drm]] Modeline
126:"640x480" 60 25200 640 656 752 800 480 490 492 525 0x40 0xa
[  853.587188] [drm:drm_mode_debug_printmodeline [drm]] Modeline
101:"640x480" 60 25175 640 656 752 800 480 490 492 525 0x40 0xa
[  853.587192] [drm:drm_mode_debug_printmodeline [drm]] Modeline
102:"720x400" 70 28320 720 738 846 900 400 412 414 449 0x40 0x6
[  853.587206] [drm:drm_helper_probe_single_connector_modes
[drm_kms_helper]] [CONNECTOR:73:HDMI-A-1]



When it fails:
[   11.118971] [drm:drm_detect_monitor_audio [drm]] Monitor has basic
audio support
[   11.119633] [drm:drm_add_display_info [drm]] non_desktop set to 0
[   11.119640] [drm:drm_add_display_info [drm]] HDMI: DVI dual 0, max
TMDS clock 300000 kHz
[   11.119648] [drm:drm_add_display_info [drm]] non_desktop set to 0
[   11.119653] [drm:drm_add_display_info [drm]] HDMI: DVI dual 0, max
TMDS clock 300000 kHz
[   11.119747] [drm:drm_edid_to_eld [drm]] ELD monitor Q2775
[   11.119753] [drm:drm_edid_to_eld [drm]] HDMI: latency present 0 0,
video latency 0 0, audio latency 0 0
[   11.119782] [drm:intel_connector_update_modes [i915]] ELD size 28,
SAD count 1
[   11.119873] [drm:drm_mode_debug_printmodeline [drm]] Modeline
107:"2560x1440" 60 241500 2560 2608 2640 2720 1440 1443 1448 1481 0x48
0x5
[   11.119879] [drm:drm_mode_prune_invalid [drm]] Not using 2560x1440
mode: CLOCK_HIGH
[   11.119886] [drm:drm_helper_probe_single_connector_modes
[drm_kms_helper]] [CONNECTOR:69:DP-1] probed modes :
[   11.119892] [drm:drm_mode_debug_printmodeline [drm]] Modeline
80:"1920x1080" 60 148500 1920 2008 2052 2200 1080 1084 1089 1125 0x40
0x5
[   11.119898] [drm:drm_mode_debug_printmodeline [drm]] Modeline
114:"1920x1080" 60 148352 1920 2008 2052 2200 1080 1084 1089 1125 0x40
0x5
[   11.119903] [drm:drm_mode_debug_printmodeline [drm]] Modeline
105:"1920x1080i" 60 74250 1920 2008 2052 2200 1080 1084 1094 1125 0x40
0x15
[   11.119909] [drm:drm_mode_debug_printmodeline [drm]] Modeline
119:"1920x1080i" 60 74176 1920 2008 2052 2200 1080 1084 1094 1125 0x40
0x15
[   11.119914] [drm:drm_mode_debug_printmodeline [drm]] Modeline
104:"1920x1080" 50 148500 1920 2448 2492 2640 1080 1084 1089 1125 0x40
0x5
[   11.119919] [drm:drm_mode_debug_printmodeline [drm]] Modeline
106:"1920x1080i" 50 74250 1920 2448 2492 2640 1080 1084 1094 1125 0x40
0x15
[   11.119924] [drm:drm_mode_debug_printmodeline [drm]] Modeline
84:"1280x1440" 60 156000 1280 1376 1512 1744 1440 1443 1453 1493 0x40
0x6
[   11.119929] [drm:drm_mode_debug_printmodeline [drm]] Modeline
85:"1680x1050" 60 119000 1680 1728 1760 1840 1050 1053 1059 1080 0x40
0x9
[   11.119934] [drm:drm_mode_debug_printmodeline [drm]] Modeline
96:"1280x1024" 75 135000 1280 1296 1440 1688 1024 1025 1028 1066 0x40
0x5
[   11.119939] [drm:drm_mode_debug_printmodeline [drm]] Modeline
87:"1280x1024" 60 108000 1280 1328 1440 1688 1024 1025 1028 1066 0x40
0x5
[   11.119945] [drm:drm_mode_debug_printmodeline [drm]] Modeline
86:"1440x900" 60 88750 1440 1488 1520 1600 900 903 909 926 0x40 0x9
[   11.119950] [drm:drm_mode_debug_printmodeline [drm]] Modeline
88:"1280x960" 60 108000 1280 1376 1488 1800 960 961 964 1000 0x40 0x5
[   11.119955] [drm:drm_mode_debug_printmodeline [drm]] Modeline
81:"1280x720" 60 74250 1280 1390 1430 1650 720 725 730 750 0x40 0x5
[   11.119960] [drm:drm_mode_debug_printmodeline [drm]] Modeline
115:"1280x720" 60 74176 1280 1390 1430 1650 720 725 730 750 0x40 0x5
[   11.119965] [drm:drm_mode_debug_printmodeline [drm]] Modeline
108:"1280x720" 50 74250 1280 1720 1760 1980 720 725 730 750 0x40 0x5
[   11.119970] [drm:drm_mode_debug_printmodeline [drm]] Modeline
97:"1024x768" 75 78750 1024 1040 1136 1312 768 769 772 800 0x40 0x5
[   11.119975] [drm:drm_mode_debug_printmodeline [drm]] Modeline
98:"1024x768" 70 75000 1024 1048 1184 1328 768 771 777 806 0x40 0xa
[   11.119980] [drm:drm_mode_debug_printmodeline [drm]] Modeline
99:"1024x768" 60 65000 1024 1048 1184 1344 768 771 777 806 0x40 0xa
[   11.119985] [drm:drm_mode_debug_printmodeline [drm]] Modeline
100:"832x624" 75 57284 832 864 928 1152 624 625 628 667 0x40 0xa
[   11.119990] [drm:drm_mode_debug_printmodeline [drm]] Modeline
101:"800x600" 75 49500 800 816 896 1056 600 601 604 625 0x40 0x5
[   11.119995] [drm:drm_mode_debug_printmodeline [drm]] Modeline
102:"800x600" 72 50000 800 856 976 1040 600 637 643 666 0x40 0x5
[   11.120000] [drm:drm_mode_debug_printmodeline [drm]] Modeline
89:"800x600" 60 40000 800 840 968 1056 600 601 605 628 0x40 0x5
[   11.120018] [drm:drm_mode_debug_printmodeline [drm]] Modeline
90:"800x600" 56 36000 800 824 896 1024 600 601 603 625 0x40 0x5
[   11.120023] [drm:drm_mode_debug_printmodeline [drm]] Modeline
83:"720x576" 50 27000 720 732 796 864 576 581 586 625 0x40 0xa
[   11.120028] [drm:drm_mode_debug_printmodeline [drm]] Modeline
116:"720x480" 60 27027 720 736 798 858 480 489 495 525 0x40 0xa
[   11.120033] [drm:drm_mode_debug_printmodeline [drm]] Modeline
82:"720x480" 60 27000 720 736 798 858 480 489 495 525 0x40 0xa
[   11.120038] [drm:drm_mode_debug_printmodeline [drm]] Modeline
91:"640x480" 75 31500 640 656 720 840 480 481 484 500 0x40 0xa
[   11.120043] [drm:drm_mode_debug_printmodeline [drm]] Modeline
92:"640x480" 73 31500 640 664 704 832 480 489 492 520 0x40 0xa
[   11.120048] [drm:drm_mode_debug_printmodeline [drm]] Modeline
93:"640x480" 67 30240 640 704 768 864 480 483 486 525 0x40 0xa
[   11.120053] [drm:drm_mode_debug_printmodeline [drm]] Modeline
117:"640x480" 60 25200 640 656 752 800 480 490 492 525 0x40 0xa
[   11.120058] [drm:drm_mode_debug_printmodeline [drm]] Modeline
94:"640x480" 60 25175 640 656 752 800 480 490 492 525 0x40 0xa
[   11.120064] [drm:drm_mode_debug_printmodeline [drm]] Modeline
95:"720x400" 70 28320 720 738 846 900 400 412 414 449 0x40 0x6
[   11.120089] [drm:drm_helper_probe_single_connector_modes
[drm_kms_helper]] [CONNECTOR:73:HDMI-A-1]


Thanks!

-- 
Ricardo Ribalda

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