[FS#863] ath9k failure with AP+11s VIFs ("unsupported hw bitrate detected")

[LEDE Bugs]

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FS#863 - ath9k failure with AP+11s VIFs ("unsupported hw bitrate detected")
User who did this - komar (ramok)

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Same on Ubiquti Bullet M2, Reboot (17.01-SNAPSHOT, r3535+34-ee32de4426).

WPA2/PSK connection

[68667.891551] WARNING: CPU: 0 PID: 0 at compat-wireless-2017-01-31/net/mac80211/rx.c:4214 ieee80211_rx_napi+0x130/0x8b0 [mac80211]()
[68667.903350] Rate marked as an HT rate but passed status->rate_idx is not an MCS index [0-76]: 123 (0x7b)
[68667.912861] Modules linked in: iptable_nat ath9k nf_nat_ipv4 nf_conntrack_ipv6 nf_conntrack_ipv4 ipt_REJECT ipt_MASQUERADE ebtable_nat ebtable_filter ebtable_broute ath9k_common xt_time xt_tcpudp xt_tcpmss xt_statistic xt_state xt_nat xt_multiport xt_mark xt_mac xt_limit xt_length xt_hl xt_ecn xt_dscp xt_conntrack xt_comment xt_TCPMSS xt_REDIRECT xt_LOG xt_HL xt_DSCP xt_CT xt_CLASSIFY nf_reject_ipv4 nf_nat_redirect nf_nat_masquerade_ipv4 nf_nat nf_log_ipv4 nf_defrag_ipv6 nf_defrag_ipv4 nf_conntrack_rtcache nf_conntrack mac80211 iptable_mangle iptable_filter ipt_ECN ip_tables ebtables ebt_vlan ebt_stp ebt_snat ebt_redirect ebt_pkttype ebt_mark_m ebt_mark ebt_limit ebt_ip6 ebt_ip ebt_dnat ebt_arpreply ebt_arp ebt_among ebt_802_3 br_netfilter ath9k_hw ath batman_adv libcrc32c cfg80211 compat xt_set ip_set_list_set ip_set_hash_netiface ip_set_hash_netport ip_set_hash_netnet ip_set_hash_net ip_set_hash_netportnet ip_set_hash_mac ip_set_hash_ipportnet ip_set_hash_ipportip ip_set_hash_ipport ip_set_hash_ipmark ip_set_hash_ip ip_set_bitmap_port ip_set_bitmap_ipmac ip_set_bitmap_ip ip_set nfnetlink ip6t_REJECT nf_reject_ipv6 nf_log_ipv6 nf_log_common ip6table_mangle ip6table_filter ip6_tables x_tables dummy veth ohci_platform ohci_hcd ehci_platform ehci_hcd gpio_button_hotplug usbcore nls_base usb_common crc16 crc32c_generic crypto_hash
[68668.031742] CPU: 0 PID: 0 Comm: swapper Tainted: G        W       4.4.89 #0
[68668.038732] Stack : 803e3444 00000000 00000001 80440000 8042d1dc 8042ce63 803c4a38 00000000
[68668.038732] 	  804a378c 00000000 00000000 00000030 00000000 800a7844 803ca150 80430000
[68668.038732] 	  00000003 00000000 803c855c 81809d5c 00000000 800a57c0 00000002 00000000
[68668.038732] 	  8042bf70 801f5a00 00000000 00000000 00000000 00000000 00000000 00000000
[68668.038732] 	  00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[68668.038732] 	  ...
[68668.074666] Call Trace:
[68668.077148] [] show_stack+0x54/0x88
[68668.081539] [] warn_slowpath_common+0xa0/0xd0
[68668.086807] [] warn_slowpath_fmt+0x2c/0x38
[68668.091946] [] ieee80211_rx_napi+0x130/0x8b0 [mac80211]
[68668.098206] [] ath_rx_tasklet+0xee8/0xf4c [ath9k]
[68668.103828] [] ath9k_tasklet+0x200/0x28c [ath9k]
[68668.109376] [] tasklet_action+0x80/0xc8
[68668.114103] [] __do_softirq+0x250/0x298
[68668.118863] [] plat_irq_dispatch+0xd4/0x10c
[68668.123927] 
[68668.125428] ---[ end trace ad42afcfef337e45 ]---


I have AP and 3 STA clients connected to AP. All 4 devices are the same Ubiquti Bullet M2 hardware and same firmware.

This in on AP device:

$ iw dev wlan-ap station dump | grep 'bitra\|Station'
Station 68:72:51:24:bc:9b (on wlan-ap)
	tx bitrate:	1.0 MBit/s