OpenWrt/LEDE Project

  • Status Unconfirmed
  • Percent Complete
    0%
  • Task Type Bug Report
  • Category Kernel
  • Assigned To No-one
  • Operating System All
  • Severity Medium
  • Priority Very Low
  • Reported Version openwrt-19.07
  • Due in Version Undecided
  • Due Date Undecided
  • Private
Attached to Project: OpenWrt/LEDE Project
Opened by Thomas Beckler - 09.05.2020

FS#3080 - ramips/mt7621 Netgear R6220 WIFI 5 GHz issue

I am using a Netgear R6220 router. My router has one “bad erase block”

[    2.859177] Scanning device for bad blocks
[    2.952205] Bad eraseblock 361 at 0x000002d20000
[    3.116833] 6 fixed-partitions partitions found on MTD device MT7621-NAND

Every test is done with default settings. For me it is easier to debug this issue with openwrt in station mode, but it applies to AccessPoint/Master as well.

  • 2.4 GHz WIFI operation as expected
  • 5 GHz WIFI only affected
  • low throughput only in openwrt TX direction / openwrt RX direction OK
  • things got much worse with openwrt 19.07.02 → openwrt 18.06.08 was better
    This is why I suspect that it is related to FS#1926 - MTD partition offset not correctly mapped when bad eraseblocks present.
    This fix has been integrated in 19.07. I don’t want to revert this change, as this is the first version openwrt sets the correct MAC address.

Comarison of OpenWrt 18.06.08 and 19.07.02

  • OpenWrt 18.06.08: TX Power is set to 3dBm
  • OpenWrt 19.07.02: TX Power is set to 20dBm (default?)
  • In both cases/logs The “HT Mode is VHT80”
  • Changing the TX Power in 19.07.02 has no effect
    Resource is busy

My guess/conclusion is that

  • the calibration data is not taken into account (maybe it was never and openwrt 18.06 was just lucky)
  • The offset to read the calibration data has changed with openwrt 19.07.02. This is why things got worse (for me)

Attached is the mtd4.bin (factory). I don’t know if this helps for this issue.

OpenWrt 18.06.08

WIFI 5 GHz operation “normal”. Means I can use any channel in 5 GHz and get good performance/throughput.
Channel 36
TX ~80Mbit/s
RX ~95Mbit/s
Channel 124
TX ~80Mbit/s
RX ~95Mbit/s

iw --debug phy phy1 info
phy phy1
        max # scan SSIDs: 4
        max scan IEs length: 2247 bytes
        max # sched scan SSIDs: 0
        max # match sets: 0
        max # scan plans: 1
        max scan plan interval: -1
        max scan plan iterations: 0
        Retry short limit: 7
        Retry long limit: 4
        Coverage class: 0 (up to 0m)
        Available Antennas: TX 0x3 RX 0x3
        Configured Antennas: TX 0x3 RX 0x3
        Supported interface modes:
                 * IBSS
                 * managed
                 * AP
                 * AP/VLAN
                 * monitor
                 * mesh point
        Band 2:
                Capabilities: 0x1ff
                        RX LDPC
                        HT20/HT40
                        SM Power Save disabled
                        RX Greenfield
                        RX HT20 SGI
                        RX HT40 SGI
                        TX STBC
                        RX STBC 1-stream
                        Max AMSDU length: 3839 bytes
                        No DSSS/CCK HT40
                Maximum RX AMPDU length 65535 bytes (exponent: 0x003)
                Minimum RX AMPDU time spacing: 4 usec (0x05)
                HT TX/RX MCS rate indexes supported: 0-15
                VHT Capabilities (0x018001b0):
                        Max MPDU length: 3895
                        Supported Channel Width: neither 160 nor 80+80
                        RX LDPC
                        short GI (80 MHz)
                        TX STBC
                VHT RX MCS set:
                        1 streams: MCS 0-9
                        2 streams: MCS 0-9
                        3 streams: not supported
                        4 streams: not supported
                        5 streams: not supported
                        6 streams: not supported
                        7 streams: not supported
                        8 streams: not supported
                VHT RX highest supported: 0 Mbps
                VHT TX MCS set:
                        1 streams: MCS 0-9
                        2 streams: MCS 0-9
                        3 streams: not supported
                        4 streams: not supported
                        5 streams: not supported
                        6 streams: not supported
                        7 streams: not supported
                        8 streams: not supported
                VHT TX highest supported: 0 Mbps
                Frequencies:
                        * 5180 MHz [36] (3.0 dBm)
                        * 5200 MHz [40] (3.0 dBm)
                        * 5220 MHz [44] (3.0 dBm)
                        * 5240 MHz [48] (3.0 dBm)
                        * 5260 MHz [52] (3.0 dBm) (no IR, radar detection)
                        * 5280 MHz [56] (3.0 dBm) (no IR, radar detection)
                        * 5300 MHz [60] (3.0 dBm) (no IR, radar detection)
                        * 5320 MHz [64] (3.0 dBm) (no IR, radar detection)
                        * 5500 MHz [100] (3.0 dBm) (no IR, radar detection)
                        * 5520 MHz [104] (3.0 dBm) (no IR, radar detection)
                        * 5540 MHz [108] (3.0 dBm) (no IR, radar detection)
                        * 5560 MHz [112] (3.0 dBm) (no IR, radar detection)
                        * 5580 MHz [116] (3.0 dBm) (no IR, radar detection)
                        * 5600 MHz [120] (3.0 dBm) (no IR, radar detection)
                        * 5620 MHz [124] (3.0 dBm) (no IR, radar detection)
                        * 5640 MHz [128] (3.0 dBm) (no IR, radar detection)
                        * 5660 MHz [132] (3.0 dBm) (no IR, radar detection)
                        * 5680 MHz [136] (3.0 dBm) (no IR, radar detection)
                        * 5700 MHz [140] (3.0 dBm) (no IR, radar detection)
                        * 5745 MHz [149] (3.0 dBm) (no IR)
                        * 5765 MHz [153] (3.0 dBm) (no IR)
                        * 5785 MHz [157] (3.0 dBm) (no IR)
                        * 5805 MHz [161] (3.0 dBm) (no IR)
                        * 5825 MHz [165] (3.0 dBm) (no IR)
        valid interface combinations:
                 * #{ IBSS } <= 1, #{ managed, AP, mesh point } <= 8,
                   total <= 8, #channels <= 1, STA/AP BI must match, radar detect widths: { 20 MHz (no HT), 20 MHz, 40 MHz, 80 MHz }

        HT Capability overrides:
                 * MCS: ff ff ff ff ff ff ff ff ff ff
                 * maximum A-MSDU length
                 * supported channel width
                 * short GI for 40 MHz
                 * max A-MPDU length exponent
                 * min MPDU start spacing
        Device supports VHT-IBSS.
root@OpenWrt:~# iw --debug wlan1 info
Interface wlan1
        ifindex 8
        wdev 0x100000002
        addr xx:xx:xx:xx:xx:xx
        ssid Africa_5GHz
        type managed
        wiphy 1
        channel 124 (5620 MHz), width: 80 MHz, center1: 5610 MHz
        txpower 3.00 dBm
wifi status
"radio1": {
                "up": true,
                "pending": false,
                "autostart": true,
                "disabled": false,
                "retry_setup_failed": false,
                "config": {
                        "hwmode": "11a",
                        "path": "pci0000:00\/0000:00:00.0\/0000:01:00.0",
                        **"htmode": "VHT80",**
                        "channel": "124",
                        "country": "00",
                        "legacy_rates": true,
                        "disabled": false

OpenWrt 19.07.02

Channel 36
TX ~1.25 Mbit/s
RX ~95 Mbit/s
Channel 124
TX ~1.25 Mbit/s
RX ~95 Mbit/s

root@OpenWrt:~# iw --debug phy1 info
Wiphy phy1
        max # scan SSIDs: 4
        max scan IEs length: 2247 bytes
        max # sched scan SSIDs: 0
        max # match sets: 0
        max # scan plans: 1
        max scan plan interval: -1
        max scan plan iterations: 0
        Retry short limit: 7
        Retry long limit: 4
        Coverage class: 0 (up to 0m)
        Available Antennas: TX 0x3 RX 0x3
        Configured Antennas: TX 0x3 RX 0x3
        Supported interface modes:
                 * IBSS
                 * managed
                 * AP
                 * AP/VLAN
                 * monitor
                 * mesh point
        Band 2:
                Capabilities: 0x1ff
                        RX LDPC
                        HT20/HT40
                        SM Power Save disabled
                        RX Greenfield
                        RX HT20 SGI
                        RX HT40 SGI
                        TX STBC
                        RX STBC 1-stream
                        Max AMSDU length: 3839 bytes
                        No DSSS/CCK HT40
                Maximum RX AMPDU length 65535 bytes (exponent: 0x003)
                Minimum RX AMPDU time spacing: 4 usec (0x05)
                HT TX/RX MCS rate indexes supported: 0-15
                VHT Capabilities (0x318001b0):
                        Max MPDU length: 3895
                        Supported Channel Width: neither 160 nor 80+80
                        RX LDPC
                        short GI (80 MHz)
                        TX STBC
                        RX antenna pattern consistency
                        TX antenna pattern consistency
                VHT RX MCS set:
                        1 streams: MCS 0-9
                        2 streams: MCS 0-9
                        3 streams: not supported
                        4 streams: not supported
                        5 streams: not supported
                        6 streams: not supported
                        7 streams: not supported
                        8 streams: not supported
                VHT RX highest supported: 0 Mbps
                VHT TX MCS set:
                        1 streams: MCS 0-9
                        2 streams: MCS 0-9
                        3 streams: not supported
                        4 streams: not supported
                        5 streams: not supported
                        6 streams: not supported
                        7 streams: not supported
                        8 streams: not supported
                VHT TX highest supported: 0 Mbps
                Frequencies:
                        * 5180 MHz [36] (20.0 dBm)
                        * 5200 MHz [40] (20.0 dBm)
                        * 5220 MHz [44] (20.0 dBm)
                        * 5240 MHz [48] (20.0 dBm)
                        * 5260 MHz [52] (20.0 dBm) (no IR, radar detection)
                        * 5280 MHz [56] (20.0 dBm) (no IR, radar detection)
                        * 5300 MHz [60] (20.0 dBm) (no IR, radar detection)
                        * 5320 MHz [64] (20.0 dBm) (no IR, radar detection)
                        * 5500 MHz [100] (20.0 dBm) (no IR, radar detection)
                        * 5520 MHz [104] (20.0 dBm) (no IR, radar detection)
                        * 5540 MHz [108] (20.0 dBm) (no IR, radar detection)
                        * 5560 MHz [112] (20.0 dBm) (no IR, radar detection)
                        * 5580 MHz [116] (20.0 dBm) (no IR, radar detection)
                        * 5600 MHz [120] (20.0 dBm) (no IR, radar detection)
                        * 5620 MHz [124] (20.0 dBm) (no IR, radar detection)
                        * 5640 MHz [128] (20.0 dBm) (no IR, radar detection)
                        * 5660 MHz [132] (20.0 dBm) (no IR, radar detection)
                        * 5680 MHz [136] (20.0 dBm) (no IR, radar detection)
                        * 5700 MHz [140] (20.0 dBm) (no IR, radar detection)
                        * 5745 MHz [149] (20.0 dBm) (no IR)
                        * 5765 MHz [153] (20.0 dBm) (no IR)
                        * 5785 MHz [157] (20.0 dBm) (no IR)
                        * 5805 MHz [161] (20.0 dBm) (no IR)
                        * 5825 MHz [165] (20.0 dBm) (no IR)
        valid interface combinations:
                 * #{ IBSS } <= 1, #{ managed, AP, mesh point } <= 8,
                   total <= 8, #channels <= 1, STA/AP BI must match, radar detect widths: { 20 MHz (no HT), 20 MHz, 40 MHz, 80 MHz }

        HT Capability overrides:
                 * MCS: ff ff ff ff ff ff ff ff ff ff
                 * maximum A-MSDU length
                 * supported channel width
                 * short GI for 40 MHz
                 * max A-MPDU length exponent
                 * min MPDU start spacing
        Supported extended features:
                * [ VHT_IBSS ]: VHT-IBSS
                * [ RRM ]: RRM
                * [ CQM_RSSI_LIST ]: multiple CQM_RSSI_THOLD records
                * [ CONTROL_PORT_OVER_NL80211 ]: control port over nl80211
                * [ TXQS ]: FQ-CoDel-enabled intermediate TXQs
root@OpenWrt:~# iw --debug wlan1 info
Interface wlan1
        ifindex 9
        wdev 0x100000003
        addr xx:xx:xx:xx:xx:xx
        ssid Africa_5GHz
        type managed
        wiphy 1
        channel 124 (5620 MHz), width: 80 MHz, center1: 5610 MHz
        txpower 20.00 dBm
        multicast TXQ:
                qsz-byt qsz-pkt flows   drops   marks   overlmt hashcol tx-bytestx-packets
                0       0       0       0       0       0       0       0      0
wifi status
"radio1": {
                "up": false,
                "pending": false,
                "autostart": false,
                "disabled": false,
                "retry_setup_failed": false,
                "config": {
                        "hwmode": "11a",
                        "path": "pci0000:00/0000:00:00.0/0000:01:00.0",
                        "htmode": "VHT80",
                        "channel": "124",
                        "country": "00",
                        "legacy_rates": false
Thomas Beckler commented on 09.05.2020 14:40

going back to my own compilation based on openwrt 18.06.01
→ 5 GHz WIFI has never worked well but it was not as bad as with 19.07.02. I have several backups of the flash. Can someone help me to

  • adjust the read offset for the calibration data?
  • understand how i find the correct offset?
Project Manager
Adrian Schmutzler commented on 09.07.2020 19:01

Typically, the bad blocks are "normal" with NAND devices, and not inherently related to WiFi issues. However, I remotely remember that there have been issues with partition alignment when bad blocks existed for these Netgear devices, and then your calibration would possibly be read from the wrong location. Are your MAC addresses correct (as they might come from calibration data, too)?

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