Problem with NAT/ip_forward

Banana Pi Router design
78

Other issue - when we try to build the bridge interface from lan ports. When we setup bridge interface without connected cable to one of lan ports everything is OK, but when we connect cable to one of lan ports on console we receive:

slackarm login: [   38.611644] 8<--- cut here ---
[   38.620228] Unable to handle kernel NULL pointer dereference at virtual address 00000000
[   38.633919] pgd = 9c2602ba
[   38.644235] [00000000] *pgd=00000000
[   38.655360] Internal error: Oops: 80000007 [#1] SMP ARM
[   38.665019] Modules linked in: spi_mt65xx pwm_mediatek mtk_thermal mt6577_auxadc nvmem_mtk_efuse
[   38.678313] CPU: 3 PID: 317 Comm: kworker/3:2 Not tainted 5.3.0-rc1-bpi-r2-hdmi-phylink #2
[   38.691038] Hardware name: Mediatek Cortex-A7 (Device Tree)
[   38.701008] Workqueue: events switchdev_deferred_process_work
[   38.711108] PC is at 0x0
[   38.717951] LR is at dsa_switch_event+0x5e0/0x6c8
[   38.726973] pc : [<00000000>]    lr : [<c09fc6c8>]    psr: 800f0013
[   38.737616] sp : d8571cb0  ip : 00000000  fp : d8571cf4
[   38.747211] r10: 0000000c  r9 : da9ae088  r8 : d830ef90
[   38.756768] r7 : 00000006  r6 : da9ae040  r5 : c1104c48  r4 : da9ae04c
[   38.767598] r3 : 00000000  r2 : d830ef90  r1 : 00000006  r0 : da9ae040
[   38.778377] Flags: Nzcv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment none
[   38.789788] Control: 10c5387d  Table: 9872006a  DAC: 00000051
[   38.799803] Process kworker/3:2 (pid: 317, stack limit = 0xb77dd235)
[   38.810400] Stack: (0xd8571cb0 to 0xd8572000)
[   38.818943] 1ca0:                                     a1f50000 daec8040 0000001f c1104c48
[   38.831390] 1cc0: d8571cec 917bd366 c06db2c8 ffffffff d8571d3c 00000005 00000000 00000000
[   38.843885] 1ce0: c1104c48 c09fb5dc d8571d1c d8571cf8 c014d448 c09fc0f4 c1104c48 d8571e38
[   38.856429] 1d00: d9fa4800 00000000 c09f9efc c1104c48 d8571d34 d8571d20 c014d5a8 c014d400
[   38.869001] 1d20: 00000000 0f093a97 d8571d64 d8571d38 c09f9618 c014d58c c94d5892 d830ef90
[   38.881600] 1d40: d8571e73 00000000 00000006 917bd366 d8571db4 00000000 d8571d74 d8571d68
[   38.894258] 1d60: c09fb638 c09f95cc d8571dac d8571d78 c0b51850 c09fb5e8 d83938c0 917bd366
[   38.906948] 1d80: 000003a4 ffffffff d8571e38 00000006 00000000 00000000 c11c51f0 db5b9205
[   38.919651] 1da0: d8571dbc d8571db0 c0b51878 c0b51784 d8571dcc d8571dc0 c09fb464 c0b5186c
[   38.932358] 1dc0: d8571df4 d8571dd0 c014d448 c09fb420 00000006 c11bc920 d8571e38 ffffffff
[   38.945060] 1de0: 00000000 c11c51f0 d8571e1c d8571df8 c014d8b4 c014d400 00000000 00000009
[   38.957779] 1e00: c1104c48 d8571e73 d9fa4800 d830ef90 d8571e34 d8571e20 c014d8f4 c014d868
[   38.970514] 1e20: 00000000 c0164e60 d8571e64 d8571e38 c0b514fc c014d8d8 d9fa4800 00000000
[   38.983286] 1e40: d830ef90 d8571e73 00000001 917bd366 c1104c48 d8571e73 d8571e9c d8571e68
[   38.996091] 1e60: c0b51604 c0b514b4 00000000 c014d448 00571ea4 917bd366 c014d448 d830ef80
[   39.008922] 1e80: d830ef90 d9fa4800 00000100 00000000 d8571ebc d8571ea0 c0b516a4 c0b5156c
[   39.021786] 1ea0: d830ef80 c11bc918 c123516c 00000100 d8571ee4 d8571ec0 c0b512f0 c0b5168c
[   39.034651] 1ec0: 6f504bff c08a1c54 c11bc93c daa5dd80 db5b6100 db5b9200 d8571ef4 d8571ee8
[   39.047563] 1ee0: c0b513a0 c0b51278 d8571f34 d8571ef8 c0145364 c0b51390 d8570000 d8393840
[   39.060502] 1f00: d8571f1c 00000000 c0146ea8 daa5dd80 db5b6100 daa5dd94 00000008 c1103d00
[   39.073478] 1f20: db5b6118 d8570000 d8571f74 d8571f38 c01456ec c01451f4 d8393840 c0e597d4
[   39.086519] 1f40: c11c4a39 db5b6100 c014b48c d98e4c80 d8308b80 00000000 d8570000 daa5dd80
[   39.099594] 1f60: d98e4c9c da963e74 d8571fac d8571f78 c014b984 c01456a0 ffffe000 c0145694
[   39.112707] 1f80: d8571fac d8308b80 c014b848 00000000 00000000 00000000 00000000 00000000
[   39.125868] 1fa0: 00000000 d8571fb0 c01010e8 c014b854 00000000 00000000 00000000 00000000
[   39.139037] 1fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[   39.152199] 1fe0: 00000000 00000000 00000000 00000000 00000013 00000000 00000000 00000000
[   39.165324] Backtrace: 
[   39.172713] [<c09fc0e8>] (dsa_switch_event) from [<c014d448>] (notifier_call_chain+0x54/0x94)
[   39.186320]  r10:c09fb5dc r9:c1104c48 r8:00000000 r7:00000000 r6:00000005 r5:d8571d3c
[   39.199211]  r4:ffffffff
[   39.206729] [<c014d3f4>] (notifier_call_chain) from [<c014d5a8>] (raw_notifier_call_chain+0x28/0x30)
[   39.220999]  r9:c1104c48 r8:c09f9efc r7:00000000 r6:d9fa4800 r5:d8571e38 r4:c1104c48
[   39.233915] [<c014d580>] (raw_notifier_call_chain) from [<c09f9618>] (dsa_port_mdb_add+0x58/0x84)
[   39.248025] [<c09f95c0>] (dsa_port_mdb_add) from [<c09fb638>] (dsa_slave_port_obj_add+0x5c/0x78)
[   39.262079]  r4:00000000
[   39.269844] [<c09fb5dc>] (dsa_slave_port_obj_add) from [<c0b51850>] (__switchdev_handle_port_obj_add+0xd8/0xe8)
[   39.285332] [<c0b51778>] (__switchdev_handle_port_obj_add) from [<c0b51878>] (switchdev_handle_port_obj_add+0x18/0x24)
[   39.301563]  r10:db5b9205 r9:c11c51f0 r8:00000000 r7:00000000 r6:00000006 r5:d8571e38
[   39.314952]  r4:ffffffff
[   39.322993] [<c0b51860>] (switchdev_handle_port_obj_add) from [<c09fb464>] (dsa_slave_switchdev_blocking_event+0x50/0xb0)
[   39.339693] [<c09fb414>] (dsa_slave_switchdev_blocking_event) from [<c014d448>] (notifier_call_chain+0x54/0x94)
[   39.355625] [<c014d3f4>] (notifier_call_chain) from [<c014d8b4>] (__blocking_notifier_call_chain+0x58/0x70)
[   39.371295]  r9:c11c51f0 r8:00000000 r7:ffffffff r6:d8571e38 r5:c11bc920 r4:00000006
[   39.385008] [<c014d85c>] (__blocking_notifier_call_chain) from [<c014d8f4>] (blocking_notifier_call_chain+0x28/0x30)
[   39.401558]  r7:d830ef90 r6:d9fa4800 r5:d8571e73 r4:c1104c48
[   39.413216] [<c014d8cc>] (blocking_notifier_call_chain) from [<c0b514fc>] (switchdev_port_obj_notify+0x54/0xb8)
[   39.429467] [<c0b514a8>] (switchdev_port_obj_notify) from [<c0b51604>] (switchdev_port_obj_add_now+0xa4/0x120)
[   39.445702]  r5:d8571e73 r4:c1104c48
[   39.455421] [<c0b51560>] (switchdev_port_obj_add_now) from [<c0b516a4>] (switchdev_port_obj_add_deferred+0x24/0x70)
[   39.472114]  r8:00000000 r7:00000100 r6:d9fa4800 r5:d830ef90 r4:d830ef80
[   39.485051] [<c0b51680>] (switchdev_port_obj_add_deferred) from [<c0b512f0>] (switchdev_deferred_process+0x84/0x118)
[   39.501930]  r7:00000100 r6:c123516c r5:c11bc918 r4:d830ef80
[   39.513949] [<c0b5126c>] (switchdev_deferred_process) from [<c0b513a0>] (switchdev_deferred_process_work+0x1c/0x24)
[   39.530900]  r7:db5b9200 r6:db5b6100 r5:daa5dd80 r4:c11bc93c
[   39.543072] [<c0b51384>] (switchdev_deferred_process_work) from [<c0145364>] (process_one_work+0x17c/0x4ac)
[   39.559435] [<c01451e8>] (process_one_work) from [<c01456ec>] (worker_thread+0x58/0x568)
[   39.574193]  r10:d8570000 r9:db5b6118 r8:c1103d00 r7:00000008 r6:daa5dd94 r5:db5b6100
[   39.588741]  r4:daa5dd80
[   39.597977] [<c0145694>] (worker_thread) from [<c014b984>] (kthread+0x13c/0x16c)
[   39.612146]  r10:da963e74 r9:d98e4c9c r8:daa5dd80 r7:d8570000 r6:00000000 r5:d8308b80
[   39.626767]  r4:d98e4c80
[   39.636042] [<c014b848>] (kthread) from [<c01010e8>] (ret_from_fork+0x14/0x2c)
[   39.650076] Exception stack(0xd8571fb0 to 0xd8571ff8)
[   39.661907] 1fa0:                                     00000000 00000000 00000000 00000000
[   39.676923] 1fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[   39.691899] 1fe0: 00000000 00000000 00000000 00000000 00000013 00000000
[   39.705232]  r10:00000000 r9:00000000 r8:00000000 r7:00000000 r6:00000000 r5:c014b848
[   39.719771]  r4:d8308b80
[   39.728942] Code: bad PC value
[   39.738778] ---[ end trace a81843dec73e2fd1 ]---

The console (via serial) stop response and on monitor (via hdmi) is nothing - black screen only with info from monitor (no signal), but on serial console from BPI-R2 I got (when connect monitor to hdmi port):

[ 2012.441290] [drm:drm_helper_hpd_irq_event] [CONNECTOR:32:HDMI-A-1] status updated from connected to connected
[ 2012.458034] [drm:drm_helper_hpd_irq_event] [CONNECTOR:32:HDMI-A-1] status updated from connected to disconnected
[ 2012.474879] [drm:drm_sysfs_hotplug_event] generating hotplug event
[ 2012.487759] [drm:drm_fb_helper_hotplug_event.part.5] 
[ 2012.499680] [drm:drm_client_modeset_probe] 
[ 2012.510424] [drm:drm_mode_object_get] OBJ ID: 32 (4)
[ 2012.521904] [drm:drm_helper_probe_single_connector_modes] [CONNECTOR:32:HDMI-A-1]
[ 2012.535921] [drm:drm_helper_probe_single_connector_modes] [CONNECTOR:32:HDMI-A-1] status updated from disconnected to connected
[ 2012.581421] [drm:drm_detect_monitor_audio] Monitor has basic audio support
[ 2012.594912] [drm:drm_add_display_info] non_desktop set to 0
[ 2012.607044] [drm:drm_add_display_info] HDMI: DVI dual 0, max TMDS clock 0 kHz
[ 2012.620749] [drm:drm_add_edid_modes] ELD monitor PL2377
[ 2012.632475] [drm:drm_add_edid_modes] HDMI: latency present 0 0, video latency 0 0, audio latency 0 0
[ 2012.648162] [drm:drm_add_edid_modes] ELD size 32, SAD count 1
[ 2012.660467] [drm:drm_add_display_info] non_desktop set to 0
[ 2012.672507] [drm:drm_add_display_info] HDMI: DVI dual 0, max TMDS clock 0 kHz
[ 2012.687129] [drm:drm_mode_debug_printmodeline] Modeline "1280x1024": 60 108879 1280 1360 1496 1712 1024 1025 1028 1060 0x20 0x6
[ 2012.705224] [drm:drm_mode_prune_invalid] Not using 1280x1024 mode: STALE
[ 2012.718567] [drm:drm_mode_debug_printmodeline] Modeline "1920x1080": 60 148500 1920 2008 2052 2200 1080 1084 1089 1125 0x48 0x5
[ 2012.736857] [drm:drm_mode_prune_invalid] Not using 1920x1080 mode: VIRTUAL_X
[ 2012.750694] [drm:drm_mode_debug_printmodeline] Modeline "1920x1080": 50 148500 1920 2448 2492 2640 1080 1084 1089 1125 0x40 0x5
[ 2012.769028] [drm:drm_mode_prune_invalid] Not using 1920x1080 mode: VIRTUAL_X
[ 2012.782894] [drm:drm_mode_debug_printmodeline] Modeline "1920x1080i": 50 74250 1920 1936 1980 2640 1080 1084 1094 1125 0x40 0x15
[ 2012.801367] [drm:drm_mode_prune_invalid] Not using 1920x1080i mode: VIRTUAL_X
[ 2012.815371] [drm:drm_mode_debug_printmodeline] Modeline "1680x1050": 0 119000 1680 1728 1760 1840 1050 1053 1059 1080 0x40 0x9
[ 2012.833695] [drm:drm_mode_prune_invalid] Not using 1680x1050 mode: VIRTUAL_X
[ 2012.847640] [drm:drm_mode_debug_printmodeline] Modeline "1600x1200": 0 162000 1600 1664 1856 2160 1200 1201 1204 1250 0x40 0x5
[ 2012.866013] [drm:drm_mode_prune_invalid] Not using 1600x1200 mode: VIRTUAL_X
[ 2012.880004] [drm:drm_mode_debug_printmodeline] Modeline "1440x900": 0 88750 1440 1488 1520 1600 900 903 909 926 0x40 0x9
[ 2012.897852] [drm:drm_mode_prune_invalid] Not using 1440x900 mode: VIRTUAL_X
[ 2012.911731] [drm:drm_mode_debug_printmodeline] Modeline "1440x900": 0 136750 1440 1536 1688 1936 900 903 909 942 0x40 0x6
[ 2012.929645] [drm:drm_mode_prune_invalid] Not using 1440x900 mode: VIRTUAL_X
[ 2012.943542] [drm:drm_mode_debug_printmodeline] Modeline "640x480": 0 25175 640 656 752 800 480 490 492 525 0x40 0xa
[ 2012.960927] [drm:drm_mode_prune_invalid] Not using 640x480 mode: CLOCK_LOW
[ 2012.974688] [drm:drm_mode_debug_printmodeline] Modeline "1920x1080": 0 148500 1920 2448 2492 2640 1080 1084 1089 1125 0x40 0x5
[ 2012.993031] [drm:drm_mode_prune_invalid] Not using 1920x1080 mode: VIRTUAL_X
[ 2013.006980] [drm:drm_mode_debug_printmodeline] Modeline "1920x1080i": 0 74250 1920 2448 2492 2640 1080 1084 1094 1125 0x40 0x15
[ 2013.025413] [drm:drm_mode_prune_invalid] Not using 1920x1080i mode: VIRTUAL_X
[ 2013.039435] [drm:drm_mode_debug_printmodeline] Modeline "720x576i": 0 13500 720 732 795 864 576 580 586 625 0x40 0x101a
[ 2013.057138] [drm:drm_mode_prune_invalid] Not using 720x576i mode: CLOCK_LOW
[ 2013.070970] [drm:drm_mode_debug_printmodeline] Modeline "720x576i": 0 13500 720 732 795 864 576 580 586 625 0x40 0x101a
[ 2013.088665] [drm:drm_mode_prune_invalid] Not using 720x576i mode: CLOCK_LOW
[ 2013.102473] [drm:drm_mode_debug_printmodeline] Modeline "1920x1080": 0 148500 1920 2008 2052 2200 1080 1084 1089 1125 0x40 0x5
[ 2013.120759] [drm:drm_mode_prune_invalid] Not using 1920x1080 mode: VIRTUAL_X
[ 2013.134638] [drm:drm_mode_debug_printmodeline] Modeline "1920x1080i": 0 74250 1920 2008 2052 2200 1080 1084 1094 1125 0x40 0x15
[ 2013.152998] [drm:drm_mode_prune_invalid] Not using 1920x1080i mode: VIRTUAL_X
[ 2013.166954] [drm:drm_mode_debug_printmodeline] Modeline "720x480i": 0 13500 720 739 801 858 480 488 494 525 0x40 0x101a
[ 2013.184586] [drm:drm_mode_prune_invalid] Not using 720x480i mode: CLOCK_LOW
[ 2013.198340] [drm:drm_mode_debug_printmodeline] Modeline "720x480i": 0 13500 720 739 801 858 480 488 494 525 0x40 0x101a
[ 2013.215965] [drm:drm_mode_prune_invalid] Not using 720x480i mode: CLOCK_LOW
[ 2013.229743] [drm:drm_mode_debug_printmodeline] Modeline "640x480": 0 25175 640 656 752 800 480 490 492 525 0x40 0xa
[ 2013.247060] [drm:drm_mode_prune_invalid] Not using 640x480 mode: CLOCK_LOW
[ 2013.260791] [drm:drm_mode_debug_printmodeline] Modeline "1920x1080": 60 148352 1920 2008 2052 2200 1080 1084 1089 1125 0x40 0x5
[ 2013.279216] [drm:drm_mode_prune_invalid] Not using 1920x1080 mode: VIRTUAL_X
[ 2013.293188] [drm:drm_mode_debug_printmodeline] Modeline "640x480": 60 25200 640 656 752 800 480 490 492 525 0x40 0xa
[ 2013.310703] [drm:drm_mode_prune_invalid] Not using 640x480 mode: CLOCK_LOW
[ 2013.324553] [drm:drm_mode_debug_printmodeline] Modeline "1920x1080i": 60 74176 1920 2008 2052 2200 1080 1084 1094 1125 0x40 0x15
[ 2013.343182] [drm:drm_mode_prune_invalid] Not using 1920x1080i mode: VIRTUAL_X
[ 2013.357399] [drm:drm_mode_debug_printmodeline] Modeline "720x480i": 60 13514 720 739 801 858 480 488 494 525 0x40 0x101a
[ 2013.375483] [drm:drm_mode_prune_invalid] Not using 720x480i mode: CLOCK_LOW
[ 2013.389667] [drm:drm_mode_debug_printmodeline] Modeline "720x480i": 60 13514 720 739 801 858 480 488 494 525 0x40 0x101a
[ 2013.407837] [drm:drm_mode_prune_invalid] Not using 720x480i mode: CLOCK_LOW
[ 2013.422154] [drm:drm_helper_probe_single_connector_modes] [CONNECTOR:32:HDMI-A-1] probed modes :
[ 2013.438352] [drm:drm_mode_debug_printmodeline] Modeline "1280x1024": 75 135000 1280 1296 1440 1688 1024 1025 1028 1066 0x40 0x5
[ 2013.457286] [drm:drm_mode_debug_printmodeline] Modeline "1280x1024": 60 108000 1280 1328 1440 1688 1024 1025 1028 1066 0x40 0x5
[ 2013.476209] [drm:drm_mode_debug_printmodeline] Modeline "1152x864": 75 108000 1152 1216 1344 1600 864 865 868 900 0x40 0x5
[ 2013.494660] [drm:drm_mode_debug_printmodeline] Modeline "1280x720": 60 74250 1280 1390 1430 1650 720 725 730 750 0x40 0x5
[ 2013.513041] [drm:drm_mode_debug_printmodeline] Modeline "1280x720": 60 74176 1280 1390 1430 1650 720 725 730 750 0x40 0x5
[ 2013.531393] [drm:drm_mode_debug_printmodeline] Modeline "1280x720": 50 74250 1280 1720 1760 1980 720 725 730 750 0x40 0x5
[ 2013.549721] [drm:drm_mode_debug_printmodeline] Modeline "1280x720": 50 74250 1280 1720 1760 1980 720 725 730 750 0x40 0x5
[ 2013.567977] [drm:drm_mode_debug_printmodeline] Modeline "1024x768": 75 78750 1024 1040 1136 1312 768 769 772 800 0x40 0x5
[ 2013.586221] [drm:drm_mode_debug_printmodeline] Modeline "1024x768": 70 75000 1024 1048 1184 1328 768 771 777 806 0x40 0xa
[ 2013.604369] [drm:drm_mode_debug_printmodeline] Modeline "1024x768": 60 65000 1024 1048 1184 1344 768 771 777 806 0x40 0xa
[ 2013.622460] [drm:drm_mode_debug_printmodeline] Modeline "832x624": 75 57284 832 864 928 1152 624 625 628 667 0x40 0xa
[ 2013.640224] [drm:drm_mode_debug_printmodeline] Modeline "800x600": 75 49500 800 816 896 1056 600 601 604 625 0x40 0x5
[ 2013.657969] [drm:drm_mode_debug_printmodeline] Modeline "800x600": 72 50000 800 856 976 1040 600 637 643 666 0x40 0x5
[ 2013.675668] [drm:drm_mode_debug_printmodeline] Modeline "800x600": 60 40000 800 840 968 1056 600 601 605 628 0x40 0x5
[ 2013.693313] [drm:drm_mode_debug_printmodeline] Modeline "800x600": 56 36000 800 824 896 1024 600 601 603 625 0x40 0x5
[ 2013.710941] [drm:drm_mode_debug_printmodeline] Modeline "720x576": 50 27000 720 732 796 864 576 581 586 625 0x40 0xa
[ 2013.728493] [drm:drm_mode_debug_printmodeline] Modeline "720x576": 50 27000 720 732 796 864 576 581 586 625 0x40 0xa
[ 2013.745922] [drm:drm_mode_debug_printmodeline] Modeline "720x576": 50 27000 720 732 796 864 576 581 586 625 0x40 0xa
[ 2013.763229] [drm:drm_mode_debug_printmodeline] Modeline "720x480": 60 27027 720 736 798 858 480 489 495 525 0x40 0xa
[ 2013.780444] [drm:drm_mode_debug_printmodeline] Modeline "720x480": 60 27027 720 736 798 858 480 489 495 525 0x40 0xa
[ 2013.797540] [drm:drm_mode_debug_printmodeline] Modeline "720x480": 60 27000 720 736 798 858 480 489 495 525 0x40 0xa
[ 2013.814519] [drm:drm_mode_debug_printmodeline] Modeline "720x480": 60 27000 720 736 798 858 480 489 495 525 0x40 0xa
[ 2013.831378] [drm:drm_mode_debug_printmodeline] Modeline "640x480": 75 31500 640 656 720 840 480 481 484 500 0x40 0xa
[ 2013.848152] [drm:drm_mode_debug_printmodeline] Modeline "640x480": 73 31500 640 664 704 832 480 489 492 520 0x40 0xa
[ 2013.864819] [drm:drm_mode_debug_printmodeline] Modeline "640x480": 67 30240 640 704 768 864 480 483 486 525 0x40 0xa
[ 2013.881394] [drm:drm_mode_debug_printmodeline] Modeline "720x400": 70 28320 720 738 846 900 400 412 414 449 0x40 0x6
[ 2013.897890] [drm:drm_client_modeset_probe] connector 32 enabled? yes
[ 2013.910162] [drm:drm_client_modeset_probe] Not using firmware configuration
[ 2013.922969] [drm:drm_client_modeset_probe] looking for cmdline mode on connector 32
[ 2013.936410] [drm:drm_client_modeset_probe] found mode 1280x1024
[ 2013.948028] [drm:drm_client_modeset_probe] picking CRTCs for 1280x1024 config
[ 2013.960816] [drm:drm_mode_object_put] OBJ ID: 32 (4)
[ 2013.971349] [drm:drm_client_modeset_probe] desired mode 1280x1024 set on crtc 37 (0,0)
[ 2013.984852] [drm:drm_mode_object_get] OBJ ID: 32 (3)
[ 2013.995325] [drm:drm_mode_object_put] OBJ ID: 32 (4)
[ 2014.005697] mediatek-drm 14000000.dispsys: [drm:drm_client_dev_hotplug] fbdev: ret=0
[ 2014.018910] [drm:drm_helper_hpd_irq_event] [CONNECTOR:32:HDMI-A-1] status updated from connected to connected
[ 2014.034631] [drm:drm_sysfs_hotplug_event] generating hotplug event
[ 2014.046258] [drm:drm_fb_helper_hotplug_event.part.5] 
[ 2014.056649] [drm:drm_client_modeset_probe] 
[ 2014.066072] [drm:drm_mode_object_get] OBJ ID: 32 (4)
[ 2014.076209] [drm:drm_helper_probe_single_connector_modes] [CONNECTOR:32:HDMI-A-1]
[ 2014.116394] [drm:drm_detect_monitor_audio] Monitor has basic audio support
[ 2014.128396] [drm:drm_add_display_info] non_desktop set to 0
[ 2014.138991] [drm:drm_add_display_info] HDMI: DVI dual 0, max TMDS clock 0 kHz
[ 2014.151108] [drm:drm_mode_object_put] OBJ ID: 42 (1)
[ 2014.160974] [drm:drm_add_edid_modes] ELD monitor PL2377
[ 2014.171019] [drm:drm_add_edid_modes] HDMI: latency present 0 0, video latency 0 0, audio latency 0 0
[ 2014.184990] [drm:drm_add_edid_modes] ELD size 32, SAD count 1
[ 2014.195492] [drm:drm_add_display_info] non_desktop set to 0
[ 2014.205748] [drm:drm_add_display_info] HDMI: DVI dual 0, max TMDS clock 0 kHz
[ 2014.218645] [drm:drm_mode_debug_printmodeline] Modeline "1920x1080": 60 148500 1920 2008 2052 2200 1080 1084 1089 1125 0x48 0x5
[ 2014.234875] [drm:drm_mode_prune_invalid] Not using 1920x1080 mode: VIRTUAL_X
[ 2014.246604] [drm:drm_mode_debug_printmodeline] Modeline "1920x1080": 50 148500 1920 2448 2492 2640 1080 1084 1089 1125 0x40 0x5
[ 2014.262811] [drm:drm_mode_prune_invalid] Not using 1920x1080 mode: VIRTUAL_X
[ 2014.274543] [drm:drm_mode_debug_printmodeline] Modeline "1920x1080i": 50 74250 1920 1936 1980 2640 1080 1084 1094 1125 0x40 0x15
[ 2014.290901] [drm:drm_mode_prune_invalid] Not using 1920x1080i mode: VIRTUAL_X
[ 2014.302835] [drm:drm_mode_debug_printmodeline] Modeline "1680x1050": 0 119000 1680 1728 1760 1840 1050 1053 1059 1080 0x40 0x9
[ 2014.319028] [drm:drm_mode_prune_invalid] Not using 1680x1050 mode: VIRTUAL_X
[ 2014.330786] [drm:drm_mode_debug_printmodeline] Modeline "1600x1200": 0 162000 1600 1664 1856 2160 1200 1201 1204 1250 0x40 0x5
[ 2014.346949] [drm:drm_mode_prune_invalid] Not using 1600x1200 mode: VIRTUAL_X
[ 2014.358715] [drm:drm_mode_debug_printmodeline] Modeline "1440x900": 0 88750 1440 1488 1520 1600 900 903 909 926 0x40 0x9
[ 2014.374351] [drm:drm_mode_prune_invalid] Not using 1440x900 mode: VIRTUAL_X
[ 2014.386055] [drm:drm_mode_debug_printmodeline] Modeline "1440x900": 0 136750 1440 1536 1688 1936 900 903 909 942 0x40 0x6
[ 2014.401823] [drm:drm_mode_prune_invalid] Not using 1440x900 mode: VIRTUAL_X
[ 2014.413614] [drm:drm_mode_debug_printmodeline] Modeline "640x480": 0 25175 640 656 752 800 480 490 492 525 0x40 0xa
[ 2014.428950] [drm:drm_mode_prune_invalid] Not using 640x480 mode: CLOCK_LOW
[ 2014.440715] [drm:drm_mode_debug_printmodeline] Modeline "1920x1080": 0 148500 1920 2448 2492 2640 1080 1084 1089 1125 0x40 0x5
[ 2014.457163] [drm:drm_mode_prune_invalid] Not using 1920x1080 mode: VIRTUAL_X
[ 2014.469319] [drm:drm_mode_debug_printmodeline] Modeline "1920x1080i": 0 74250 1920 2448 2492 2640 1080 1084 1094 1125 0x40 0x15
[ 2014.486080] [drm:drm_mode_prune_invalid] Not using 1920x1080i mode: VIRTUAL_X
[ 2014.498527] [drm:drm_mode_debug_printmodeline] Modeline "720x576i": 0 13500 720 732 795 864 576 580 586 625 0x40 0x101a
[ 2014.514744] [drm:drm_mode_prune_invalid] Not using 720x576i mode: CLOCK_LOW
[ 2014.527195] [drm:drm_mode_debug_printmodeline] Modeline "720x576i": 0 13500 720 732 795 864 576 580 586 625 0x40 0x101a
[ 2014.543555] [drm:drm_mode_prune_invalid] Not using 720x576i mode: CLOCK_LOW
[ 2014.556106] [drm:drm_mode_debug_printmodeline] Modeline "1920x1080": 0 148500 1920 2008 2052 2200 1080 1084 1089 1125 0x40 0x5
[ 2014.573236] [drm:drm_mode_prune_invalid] Not using 1920x1080 mode: VIRTUAL_X
[ 2014.586066] [drm:drm_mode_debug_printmodeline] Modeline "1920x1080i": 0 74250 1920 2008 2052 2200 1080 1084 1094 1125 0x40 0x15
[ 2014.603479] [drm:drm_mode_prune_invalid] Not using 1920x1080i mode: VIRTUAL_X
[ 2014.616547] [drm:drm_mode_debug_printmodeline] Modeline "720x480i": 0 13500 720 739 801 858 480 488 494 525 0x40 0x101a
[ 2014.633424] [drm:drm_mode_prune_invalid] Not using 720x480i mode: CLOCK_LOW
[ 2014.646538] [drm:drm_mode_debug_printmodeline] Modeline "720x480i": 0 13500 720 739 801 858 480 488 494 525 0x40 0x101a
[ 2014.663605] [drm:drm_mode_prune_invalid] Not using 720x480i mode: CLOCK_LOW
[ 2014.676911] [drm:drm_mode_debug_printmodeline] Modeline "640x480": 0 25175 640 656 752 800 480 490 492 525 0x40 0xa
[ 2014.693837] [drm:drm_mode_prune_invalid] Not using 640x480 mode: CLOCK_LOW
[ 2014.707265] [drm:drm_mode_debug_printmodeline] Modeline "1920x1080": 60 148352 1920 2008 2052 2200 1080 1084 1089 1125 0x40 0x5
[ 2014.725447] [drm:drm_mode_prune_invalid] Not using 1920x1080 mode: VIRTUAL_X
[ 2014.739240] [drm:drm_mode_debug_printmodeline] Modeline "640x480": 60 25200 640 656 752 800 480 490 492 525 0x40 0xa
[ 2014.756630] [drm:drm_mode_prune_invalid] Not using 640x480 mode: CLOCK_LOW
[ 2014.770388] [drm:drm_mode_debug_printmodeline] Modeline "1920x1080i": 60 74176 1920 2008 2052 2200 1080 1084 1094 1125 0x40 0x15
[ 2014.788910] [drm:drm_mode_prune_invalid] Not using 1920x1080i mode: VIRTUAL_X
[ 2014.803027] [drm:drm_mode_debug_printmodeline] Modeline "720x480i": 60 13514 720 739 801 858 480 488 494 525 0x40 0x101a
[ 2014.820984] [drm:drm_mode_prune_invalid] Not using 720x480i mode: CLOCK_LOW
[ 2014.835047] [drm:drm_mode_debug_printmodeline] Modeline "720x480i": 60 13514 720 739 801 858 480 488 494 525 0x40 0x101a
[ 2014.853140] [drm:drm_mode_prune_invalid] Not using 720x480i mode: CLOCK_LOW
[ 2014.867329] [drm:drm_helper_probe_single_connector_modes] [CONNECTOR:32:HDMI-A-1] probed modes :
[ 2014.883375] [drm:drm_mode_debug_printmodeline] Modeline "1280x1024": 75 135000 1280 1296 1440 1688 1024 1025 1028 1066 0x40 0x5
[ 2014.902201] [drm:drm_mode_debug_printmodeline] Modeline "1280x1024": 60 108000 1280 1328 1440 1688 1024 1025 1028 1066 0x40 0x5
[ 2014.921027] [drm:drm_mode_debug_printmodeline] Modeline "1152x864": 75 108000 1152 1216 1344 1600 864 865 868 900 0x40 0x5
[ 2014.939401] [drm:drm_mode_debug_printmodeline] Modeline "1280x720": 60 74250 1280 1390 1430 1650 720 725 730 750 0x40 0x5
[ 2014.957641] [drm:drm_mode_debug_printmodeline] Modeline "1280x720": 60 74176 1280 1390 1430 1650 720 725 730 750 0x40 0x5
[ 2014.975781] [drm:drm_mode_debug_printmodeline] Modeline "1280x720": 50 74250 1280 1720 1760 1980 720 725 730 750 0x40 0x5
[ 2014.993879] [drm:drm_mode_debug_printmodeline] Modeline "1280x720": 50 74250 1280 1720 1760 1980 720 725 730 750 0x40 0x5
[ 2015.011939] [drm:drm_mode_debug_printmodeline] Modeline "1024x768": 75 78750 1024 1040 1136 1312 768 769 772 800 0x40 0x5
[ 2015.030008] [drm:drm_mode_debug_printmodeline] Modeline "1024x768": 70 75000 1024 1048 1184 1328 768 771 777 806 0x40 0xa
[ 2015.048031] [drm:drm_mode_debug_printmodeline] Modeline "1024x768": 60 65000 1024 1048 1184 1344 768 771 777 806 0x40 0xa
[ 2015.065984] [drm:drm_mode_debug_printmodeline] Modeline "832x624": 75 57284 832 864 928 1152 624 625 628 667 0x40 0xa
[ 2015.083602] [drm:drm_mode_debug_printmodeline] Modeline "800x600": 75 49500 800 816 896 1056 600 601 604 625 0x40 0x5
[ 2015.101217] [drm:drm_mode_debug_printmodeline] Modeline "800x600": 72 50000 800 856 976 1040 600 637 643 666 0x40 0x5
[ 2015.118790] [drm:drm_mode_debug_printmodeline] Modeline "800x600": 60 40000 800 840 968 1056 600 601 605 628 0x40 0x5
[ 2015.136345] [drm:drm_mode_debug_printmodeline] Modeline "800x600": 56 36000 800 824 896 1024 600 601 603 625 0x40 0x5
[ 2015.153849] [drm:drm_mode_debug_printmodeline] Modeline "720x576": 50 27000 720 732 796 864 576 581 586 625 0x40 0xa
[ 2015.171250] [drm:drm_mode_debug_printmodeline] Modeline "720x576": 50 27000 720 732 796 864 576 581 586 625 0x40 0xa
[ 2015.188608] [drm:drm_mode_debug_printmodeline] Modeline "720x576": 50 27000 720 732 796 864 576 581 586 625 0x40 0xa
[ 2015.205918] [drm:drm_mode_debug_printmodeline] Modeline "720x480": 60 27027 720 736 798 858 480 489 495 525 0x40 0xa
[ 2015.223136] [drm:drm_mode_debug_printmodeline] Modeline "720x480": 60 27027 720 736 798 858 480 489 495 525 0x40 0xa
[ 2015.240231] [drm:drm_mode_debug_printmodeline] Modeline "720x480": 60 27000 720 736 798 858 480 489 495 525 0x40 0xa
[ 2015.257210] [drm:drm_mode_debug_printmodeline] Modeline "720x480": 60 27000 720 736 798 858 480 489 495 525 0x40 0xa
[ 2015.274066] [drm:drm_mode_debug_printmodeline] Modeline "640x480": 75 31500 640 656 720 840 480 481 484 500 0x40 0xa
[ 2015.290837] [drm:drm_mode_debug_printmodeline] Modeline "640x480": 73 31500 640 664 704 832 480 489 492 520 0x40 0xa
[ 2015.307504] [drm:drm_mode_debug_printmodeline] Modeline "640x480": 67 30240 640 704 768 864 480 483 486 525 0x40 0xa
[ 2015.324077] [drm:drm_mode_debug_printmodeline] Modeline "720x400": 70 28320 720 738 846 900 400 412 414 449 0x40 0x6
[ 2015.340570] [drm:drm_client_modeset_probe] connector 32 enabled? yes
[ 2015.352835] [drm:drm_client_modeset_probe] Not using firmware configuration
[ 2015.365636] [drm:drm_client_modeset_probe] looking for cmdline mode on connector 32
[ 2015.379071] [drm:drm_client_modeset_probe] found mode 1280x1024
[ 2015.390684] [drm:drm_client_modeset_probe] picking CRTCs for 1280x1024 config
[ 2015.403467] [drm:drm_mode_object_put] OBJ ID: 32 (4)
[ 2015.413995] [drm:drm_client_modeset_probe] desired mode 1280x1024 set on crtc 37 (0,0)
[ 2015.427493] [drm:drm_mode_object_get] OBJ ID: 32 (3)
[ 2015.437964] [drm:drm_mode_object_put] OBJ ID: 32 (4)
[ 2015.448333] mediatek-drm 14000000.dispsys: [drm:drm_client_dev_hotplug] fbdev: ret=0

So, I think that the monitor is recognized but (maybe) fbdev crashed.

79

Oops/crash above happens is null-pointer-ref in dsa_switch_event. so it’s problem in network-stack

i test this with phylink only and report to rene

edit: seems not happen on basic phylink-branch

[   23.519202] mt7530 mdio-bus:1f lan0: phy link up gmii/1Gbps/Full                                                                                 
[   23.519234] mt7530 mdio-bus:1f lan0: phylink_mac_config: mode=phy/gmii/1Gbps/Full adv=00,00000000,00000000 pause=00 link=1 an=0                  
[   23.519636] mt7530 mdio-bus:1f lan0: Link is Up - 1Gbps/Full - flow control off                                                                  
[   23.526980] IPv6: ADDRCONF(NETDEV_CHANGE): lan0: link becomes ready                                                                              
[  104.953246] br0: port 1(lan0) entered blocking state                                                                                             
[  104.958231] br0: port 1(lan0) entered disabled state                                                                                             
[  104.963865] device lan0 entered promiscuous mode

oh, crash happens when i put the bridge up

[  269.192408] Unable to handle kernel NULL pointer dereference at virtual address 00000000                                                         
[  269.200552] pgd = ca633ada                                                                                                                       
[  269.203261] [00000000] *pgd=00000000                                                                                                             
[  269.206848] Internal error: Oops: 80000005 [#1] SMP ARM                                                                                          
[  269.212073] Modules linked in:                                                                                                                   
[  269.215134] CPU: 3 PID: 118 Comm: kworker/3:2 Not tainted 5.3.0-rc1-bpi-r2-phylink-2.5 #283                                                      
[  269.223483] Hardware name: Mediatek Cortex-A7 (Device Tree)                                                                                      
[  269.229068] Workqueue: events switchdev_deferred_process_work                                                                                    
[  269.234818] PC is at 0x0                                                                                                                         
[  269.237353] LR is at dsa_switch_event+0x640/0x6e8
...
[  269.508191] Backtrace:                                                                                                                           
[  269.510649] [<c09f3004>] (dsa_switch_event) from [<c014d4a8>] (notifier_call_chain+0x58/0x94)                                                    
[  269.519183]  r10:00000000 r9:c09f2514 r8:00000000 r7:00000005 r6:ea4b7d54 r5:00000000                                                            
[  269.527014]  r4:ffffffff                                                                                                                         
[  269.529551] [<c014d450>] (notifier_call_chain) from [<c014d608>] (raw_notifier_call_chain+0x28/0x30)                                             
[  269.538692]  r9:c09f2514 r8:c09f0e68 r7:ea2a4800 r6:00000000 r5:c1104c48 r4:c1104c48                                                             
[  269.546442] [<c014d5e0>] (raw_notifier_call_chain) from [<c09f0544>] (dsa_port_mdb_add+0x58/0x84)                                                
[  269.555323] [<c09f04ec>] (dsa_port_mdb_add) from [<c09f2570>] (dsa_slave_port_obj_add+0x5c/0x78)                                                 
[  269.564111]  r4:ea4b7e38                                                                                                                         
[  269.566649] [<c09f2514>] (dsa_slave_port_obj_add) from [<c0b482ec>] (__switchdev_handle_port_obj_add+0x64/0xe4)                                  
[  269.576745] [<c0b48288>] (__switchdev_handle_port_obj_add) from [<c0b48384>] (switchdev_handle_port_obj_add+0x18/0x24)                           
[  269.587448]  r10:00000000 r9:00000000 r8:00000000 r7:00000006 r6:ea4b7e38 r5:00000000                                                            
[  269.595278]  r4:ffffffff                                                                                                                         
[  269.597816] [<c0b4836c>] (switchdev_handle_port_obj_add) from [<c09f239c>] (dsa_slave_switchdev_blocking_event+0x50/0xb0)                        
[  269.608782] [<c09f234c>] (dsa_slave_switchdev_blocking_event) from [<c014d4a8>] (notifier_call_chain+0x58/0x94)

test now with 5.3 without phylink (and other) Patches…also happens there…so it is no phylink-problem, so i test first upgrade kernel-source to rc4

root@bpi-r2:~# ip addr del 192.168.0.11/24 dev lan0                                                                                                 
root@bpi-r2:~# brctl addbr br0                                                                                                                      
root@bpi-r2:~# ip addr add 192.168.0.11/24 dev br0                                                                                                  
root@bpi-r2:~# brctl addif br0 lan0                                                                                                                 
[   47.731914] br0: port 1(lan0) entered blocking state                                                                                             
[   47.736898] br0: port 1(lan0) entered disabled state                                                                                             
[   47.742586] device lan0 entered promiscuous mode                                                                                                 
root@bpi-r2:~# ip link set br0 up

still happens on rc4 ;(

80

I do all the test on kernel from merged branches hdmi+phylink-2.5 as I must have working hdmi and nat :wink: as a very stable without any surprises :smile:

81

it should not crash :wink:

have reported it to the dsa-maintainers: https://lkml.org/lkml/2019/8/12/376

82

OK. Thanks. So now, we must wait for their response and back to test again after them work :slight_smile:

83

seems to be fixed by this commit:

https://git.kernel.org/pub/scm/linux/kernel/git/davem/net.git/commit/?id=58799865be84e2a895dab72de0e1b996ed943f22

have added it to my repo (5.3-rc) so you can fetch and cherry-pick it

git fetch
git cherry-pick 17494d3884cd0c5cf8367ae6e8219e00fa53983c

and build again…

1 Like
84

In this repo you have mainline network driver as I remember. With this, NAT can’t work on each BPI-R2 board. I must use phylink network driver. Thanks for info about this commit.

85

You can get this commit with cherry-pick in your merged (phylink+hdmi) version

86

Great. Thanks for info and your time/help.

ed1: @frank-w I should do full kernel rebuild or will be enough to run ./build.sh build and then ./build.sh pack to have a kernel with applied this commit?

ed2: OK, I see that ./build.sh build and then ./build.sh pack is enough.

87

You can also use only build.sh (without param). This compiles (build-option) and let you choose to install on sdcard,pack,create deb or upload to tftp after compilation

This is the preferred way for interactive use…the commands build,pack,… are designed for automatic build (like travis-ci)

88

Seems the mdb-fix is merged shortly after rc4…i will rebase 5.3-rc on rc6 tomorrow

89

[answer delayed, as I was on holiday]

With applied mdb-fix (for bridge) on my merged branch phylink+hdmi seems that NAT works correctly. I’m able do download 100mb test file from the internet on test-PC connected behind the BPI-R2 as a router.

One little thing: on this BPI-R2 on which NAT doesn’t work at all on kernel 4.16 and occurs problem with second gmac (switched ports) - some of bigger icmp packages are lost, the speed via NAT is lower then directly on BPI-R2:

On this BPI-R2:

root@slackarm:~# wget http://noc.pirx.pl/100mb.bin -O /dev/null
--2019-08-26 11:11:40--  http://noc.pirx.pl/100mb.bin
Resolving noc.pirx.pl (noc.pirx.pl)... 217.73.181.197
Connecting to noc.pirx.pl (noc.pirx.pl)|217.73.181.197|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 104857600 (100M) [application/octet-stream]
Saving to: ‘/dev/null’

/dev/null           100%[===================>] 100.00M  9.23MB/s    in 10s     

2019-08-26 11:11:51 (9.71 MB/s) - ‘/dev/null’ saved [104857600/104857600]

On test-PC behind the above BPI-R2:

root@slackware:~# /usr/bin/wget http://noc.pirx.pl/100mb.bin -O /dev/null
--2009-03-28 22:27:34--  http://noc.pirx.pl/100mb.bin
Resolving noc.pirx.pl (noc.pirx.pl)... 217.73.181.197
Connecting to noc.pirx.pl (noc.pirx.pl)|217.73.181.197|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 104857600 (100M) [application/octet-stream]
Saving to: '/dev/null'

/dev/null                                    100%[=============================================================================================>] 100.00M  4.13MB/s    in 24s     

2009-03-28 22:27:58 (4.10 MB/s) - '/dev/null' saved [104857600/104857600]

Of course, this is better than if not working at all :slight_smile:

ed1. Of course, I tested this kernel 5.3.0-rc1-bpi-r2-hdmi-phylink with applied patch at all problematic BPI-R2, which I used for tests before on older kernel version.

90

if i understand you right, you have only problems on 4.16?

5.3-phylink works without any issues?

phylink seems to get merged on 5.4 (next LTS) so we don’t need to focus on older kernel-version, at least not on non-lts 4.16

btw. 4.16 does not have second gmac…

imho also when bridging ports all traffic goes to CPU and you have only 1GBit/s between switch and SOC…so traffic from e.g. lan0 to lan1 is together 1GBit/s (if you try to make bi-directional 1GBit/s), iperf should work in both directions (1 Gbit/s 0->1 and 1 Gbit/s 1->0)

1Git/s = ~940 Mbit/s

91

I have problems on 4.16 and 4.19 which I have recompiled/prepared for my requirements and made tests on this kernel versions (for tests I use standard config to avoid some other issues :slight_smile: ). These problems are not see on kernel 4.4 (I had run this version to test NAT only).

Yes, on 5.3-phylink all NAT test all passed, so looks that NAT works well.

Thanks for this description.

92

On 4.19-main there is second gmac i have ported from 4.14,but afaik the switch-setup is wrong (thats the cause we need to set both gmac to trgmii and maybe this cause transmit-timeouts). You can try 4.19 without 2nd gmac (https://github.com/frank-w/BPI-R2-4.14/tree/4.19-without2ndgmac) if this has same problems.

Phylink makes right switch-setup (info from rene who’s the author of these phylink-patches)

btw. 5.3-rc is now based on rc6

93

I think that tests on 4.19 are not needed, if we will have working later version of kernel - 5.3-rc or 5.4 :wink:

94

4.19 is also a LTS-Kernel while 5.4 is not out yet…but i guess the problems are still in the non-gmac-4.19 because 4.16 (which does not have this problems) is also affected

95

I’m very confused, if these are just software problems only and not hardware problems too.

96

if you have the problems only with mainline-driver and not with phylink it is a software-problem in mainline-driver (the part which is replaced by phylink)

97

If I read @mariaczi correctly problem is board-dependent. On one particular R2 things work fine but on some other R2 boards there are NAT failures. It leaves a big possibility for the problem to be hardware too. For example it might be some comminication line whose traces on board happen to be laid in a way so it experiences some EMI. EMI severity might differ from board to board leading to a situation when things seem to work fine on some boards but totally fail on other. As often happens HW problems might have a workaround or a fix using some software trick. With things like EMI it might be configuring PLLs to latch to slightly different freq or configuring hardware to use more robust communication protocol. Even things like slightly different HW usage pattern might be a game changer.

Offtop example

For example last week I’ve been debugging RAM problems on my home workstation after performing CPU and MB upgrade. Four DDR4 2400 modules that were working fine together in previous MB started to sometimes produce errors in “Random pattern” memtest86+ test. OS behaviour also became unstable sometimes failing with BSODs/kernel panics, but only on reboots. Tried testing each module on its own - no errors. Tried testing modules in pairs for each possible permutations - no errors as long as only one pair is used. Installed new CPU into old MB and tested four modules in there - no problems. Installed old CPU into new MB and tested all four modules for this variant - no errors. Installed new CPU back into new MB - got errors back. I’ve spent several days trying to tweak memory timings, integrated memory controller base frequency, tried increasing memory and then CPU voltages - nothing helped. Decreasing RAM frequency down to 1866 made system stable but it was not a good option as this is even slower than typical minimum DDR4 freq - 2133. And then I tried to decrease memory voltage by a 0.05V (from standard 1.2V to 1.15V) and it was like a magic wand swing, fixed the problem and allowed these four modules to run stable even when overclocked to 2866. Main conclusion here is the fact that HW problems nowdays might be really obscure and dependent on the HW configuration as done from the software side of things.