I'm not sure though. Would the dmesg log indicate that it supports the option?
[ 0.000000] Linux version 4.4.140 (buildbot@builds-02.infra.lede-project.org) (gcc version 5.4.0 (LEDE GCC 5.4.0 r3101-bce140e) ) #0 Fri Jul 13 19:25:14 2018
[ 0.000000] MyLoader: sysp=e72c40a6, boardp=3050a00a, parts=15d661ab
[ 0.000000] bootconsole [early0] enabled
[ 0.000000] CPU0 revision is: 0001974c (MIPS 74Kc)
[ 0.000000] SoC: Atheros AR9341 rev 3
[ 0.000000] Determined physical RAM map:
[ 0.000000] memory: 02000000 @ 00000000 (usable)
[ 0.000000] Initrd not found or empty - disabling initrd
[ 0.000000] No valid device tree found, continuing without
[ 0.000000] Zone ranges:
[ 0.000000] Normal [mem 0x0000000000000000-0x0000000001ffffff]
[ 0.000000] Movable zone start for each node
[ 0.000000] Early memory node ranges
[ 0.000000] node 0: [mem 0x0000000000000000-0x0000000001ffffff]
[ 0.000000] Initmem setup node 0 [mem 0x0000000000000000-0x0000000001ffffff]
[ 0.000000] On node 0 totalpages: 8192
[ 0.000000] free_area_init_node: node 0, pgdat 803de4b0, node_mem_map 81000000
[ 0.000000] Normal zone: 64 pages used for memmap
[ 0.000000] Normal zone: 0 pages reserved
[ 0.000000] Normal zone: 8192 pages, LIFO batch:0
[ 0.000000] Primary instruction cache 64kB, VIPT, 4-way, linesize 32 bytes.
[ 0.000000] Primary data cache 32kB, 4-way, VIPT, cache aliases, linesize 32 bytes
[ 0.000000] pcpu-alloc: s0 r0 d32768 u32768 alloc=1*32768
[ 0.000000] pcpu-alloc: [0] 0
[ 0.000000] Built 1 zonelists in Zone order, mobility grouping on. Total pages: 8128
[ 0.000000] Kernel command line: board=TL-MR3420-v2 console=ttyS0,115200 rootfstype=squashfs,jffs2 noinitrd
[ 0.000000] PID hash table entries: 128 (order: -3, 512 bytes)
[ 0.000000] Dentry cache hash table entries: 4096 (order: 2, 16384 bytes)
[ 0.000000] Inode-cache hash table entries: 2048 (order: 1, 8192 bytes)
[ 0.000000] Writing ErrCtl register=00000000
[ 0.000000] Readback ErrCtl register=00000000
[ 0.000000] Memory: 27800K/32768K available (3122K kernel code, 166K rwdata, 416K rodata, 320K init, 205K bss, 4968K reserved, 0K cma-reserved)
[ 0.000000] SLUB: HWalign=32, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
[ 0.000000] NR_IRQS:51
[ 0.000000] Clocks: CPU:535.000MHz, DDR:400.000MHz, AHB:200.000MHz, Ref:25.000MHz
[ 0.000000] clocksource: MIPS: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 7144898866 ns
[ 0.000011] sched_clock: 32 bits at 267MHz, resolution 3ns, wraps every 8027976190ns
[ 0.008236] Calibrating delay loop... 266.64 BogoMIPS (lpj=1333248)
[ 0.091054] pid_max: default: 32768 minimum: 301
[ 0.096067] Mount-cache hash table entries: 1024 (order: 0, 4096 bytes)
[ 0.103058] Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes)
[ 0.113269] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112604462750000 ns
[ 0.123671] futex hash table entries: 256 (order: -1, 3072 bytes)
[ 0.131394] NET: Registered protocol family 16
[ 0.137625] MIPS: machine is TP-LINK TL-MR3420 v2
[ 0.582594] Can't analyze schedule() prologue at 800670fc
[ 0.600100] clocksource: Switched to clocksource MIPS
[ 0.606686] NET: Registered protocol family 2
[ 0.612395] TCP established hash table entries: 1024 (order: 0, 4096 bytes)
[ 0.619762] TCP bind hash table entries: 1024 (order: 0, 4096 bytes)
[ 0.626535] TCP: Hash tables configured (established 1024 bind 1024)
[ 0.633351] UDP hash table entries: 256 (order: 0, 4096 bytes)
[ 0.639531] UDP-Lite hash table entries: 256 (order: 0, 4096 bytes)
[ 0.646478] NET: Registered protocol family 1
[ 0.651153] PCI: CLS 0 bytes, default 32
[ 0.656257] Crashlog allocated RAM at address 0x1f00000
[ 0.679185] squashfs: version 4.0 (2009/01/31) Phillip Lougher
[ 0.685401] jffs2: version 2.2 (NAND) (SUMMARY) (LZMA) (RTIME) (CMODE_PRIORITY) (c) 2001-2006 Red Hat, Inc.
[ 0.698613] io scheduler noop registered
[ 0.702811] io scheduler deadline registered (default)
[ 0.708463] Serial: 8250/16550 driver, 16 ports, IRQ sharing enabled
[ 0.718326] console [ttyS0] disabled
[ 0.742234] serial8250.0: ttyS0 at MMIO 0x18020000 (irq = 11, base_baud = 1562500) is a 16550A
[ 0.751345] console [ttyS0] enabled
[ 0.758892] bootconsole [early0] disabled
[ 0.773371] m25p80 spi0.0: found s25sl032p, expected m25p80
[ 0.779152] m25p80 spi0.0: s25sl032p (4096 Kbytes)
[ 0.785466] 5 tp-link partitions found on MTD device spi0.0
[ 0.791284] Creating 5 MTD partitions on "spi0.0":
[ 0.796240] 0x000000000000-0x000000020000 : "u-boot"
[ 0.803031] 0x000000020000-0x000000156d5c : "kernel"
[ 0.810005] 0x000000156d5c-0x0000003f0000 : "rootfs"
[ 0.817068] mtd: device 2 (rootfs) set to be root filesystem
[ 0.823032] 1 squashfs-split partitions found on MTD device rootfs
[ 0.829429] 0x0000003a0000-0x0000003f0000 : "rootfs_data"
[ 0.836905] 0x0000003f0000-0x000000400000 : "art"
[ 0.843749] 0x000000020000-0x0000003f0000 : "firmware"
[ 0.868912] libphy: ag71xx_mdio: probed
[ 1.462196] ag71xx ag71xx.0: connected to PHY at ag71xx-mdio.1:00 [uid=004dd042, driver=Generic PHY]
[ 1.472452] eth0: Atheros AG71xx at 0xb9000000, irq 4, mode:MII
[ 2.061981] ag71xx-mdio.1: Found an AR934X built-in switch
[ 2.104338] eth1: Atheros AG71xx at 0xba000000, irq 5, mode:GMII
[ 2.113563] NET: Registered protocol family 10
[ 2.123702] NET: Registered protocol family 17
[ 2.128377] bridge: automatic filtering via arp/ip/ip6tables has been deprecated. Update your scripts to load br_netfilter if you need this.
[ 2.141589] 8021q: 802.1Q VLAN Support v1.8
[ 2.147723] hctosys: unable to open rtc device (rtc0)
[ 2.157841] VFS: Mounted root (squashfs filesystem) readonly on device 31:2.
[ 2.167280] Freeing unused kernel memory: 320K
[ 3.286063] init: Console is alive
[ 3.289820] init: - watchdog -
[ 4.620815] kmodloader: loading kernel modules from /etc/modules-boot.d/*
[ 4.722935] usbcore: registered new interface driver usbfs
[ 4.728732] usbcore: registered new interface driver hub
[ 4.734391] usbcore: registered new device driver usb
[ 4.784766] SCSI subsystem initialized
[ 4.796093] ehci_hcd: USB 2.0 'Enhanced' Host Controller (EHCI) Driver
[ 4.804668] ehci-platform: EHCI generic platform driver
[ 4.810284] ehci-platform ehci-platform: EHCI Host Controller
[ 4.816274] ehci-platform ehci-platform: new USB bus registered, assigned bus number 1
[ 4.826586] ehci-platform ehci-platform: TX-TX IDP fix enabled
[ 4.832651] ehci-platform ehci-platform: irq 3, io mem 0x1b000000
[ 4.850148] ehci-platform ehci-platform: USB 2.0 started, EHCI 1.00
[ 4.857654] hub 1-0:1.0: USB hub found
[ 4.862048] hub 1-0:1.0: 1 port detected
[ 4.869393] ohci_hcd: USB 1.1 'Open' Host Controller (OHCI) Driver
[ 4.877518] ohci-platform: OHCI generic platform driver
[ 4.885755] uhci_hcd: USB Universal Host Controller Interface driver
[ 4.897414] usbcore: registered new interface driver usb-storage
[ 4.904404] kmodloader: done loading kernel modules from /etc/modules-boot.d/*
[ 4.914355] init: - preinit -
[ 5.470254] usb 1-1: new high-speed USB device number 2 using ehci-platform
[ 5.625767] random: procd: uninitialized urandom read (4 bytes read, 9 bits of entropy available)
[ 5.636473] usb-storage 1-1:1.0: USB Mass Storage device detected
[ 5.645229] IPv6: ADDRCONF(NETDEV_UP): eth1: link is not ready
[ 5.653388] scsi host0: usb-storage 1-1:1.0
[ 6.652151] scsi 0:0:0:0: Direct-Access Generic STORAGE DEVICE 1404 PQ: 0 ANSI: 6
[ 6.855806] sd 0:0:0:0: [sda] 15564800 512-byte logical blocks: (7.97 GB/7.42 GiB)
[ 6.865171] sd 0:0:0:0: [sda] Write Protect is off
[ 6.870204] sd 0:0:0:0: [sda] Mode Sense: 21 00 00 00
[ 6.871677] sd 0:0:0:0: [sda] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA
[ 6.889111] sda: sda1 sda2
[ 6.897918] sd 0:0:0:0: [sda] Attached SCSI removable disk
[ 7.808136] mount_root: loading kmods from internal overlay
[ 7.836335] kmodloader: loading kernel modules from //etc/modules-boot.d/*
[ 7.845202] kmodloader: done loading kernel modules from //etc/modules-boot.d/*
[ 8.129454] jffs2: notice: (441) jffs2_build_xattr_subsystem: complete building xattr subsystem, 0 of xdatum (0 unchecked, 0 orphan) and 0 of xref (0 dead, 0 orphan) found.
[ 8.145976] block: attempting to load /tmp/jffs_cfg/upper/etc/config/fstab
[ 9.483488] EXT4-fs (sda1): recovery complete
[ 9.512823] EXT4-fs (sda1): mounted filesystem with ordered data mode. Opts:
[ 9.525162] mount_root: switched to extroot
[ 9.533836] urandom-seed: Seeding with /etc/urandom.seed
[ 9.686162] procd: - early -
[ 9.689314] procd: - watchdog -
[ 10.285455] procd: - watchdog -
[ 10.289042] procd: - ubus -
[ 10.334109] random: ubusd: uninitialized urandom read (4 bytes read, 76 bits of entropy available)
[ 10.355095] random: ubusd: uninitialized urandom read (4 bytes read, 77 bits of entropy available)
[ 10.365424] random: ubusd: uninitialized urandom read (4 bytes read, 77 bits of entropy available)
[ 10.374939] random: ubusd: uninitialized urandom read (4 bytes read, 77 bits of entropy available)
[ 10.385368] random: ubusd: uninitialized urandom read (4 bytes read, 77 bits of entropy available)
[ 10.394905] random: ubusd: uninitialized urandom read (4 bytes read, 77 bits of entropy available)
[ 10.405017] random: ubusd: uninitialized urandom read (4 bytes read, 77 bits of entropy available)
[ 10.417973] random: ubusd: uninitialized urandom read (4 bytes read, 78 bits of entropy available)
[ 10.428043] Adding 524284k swap on /dev/sda2. Priority:-1 extents:1 across:524284k
[ 10.436597] procd: - init -
[ 11.836129] kmodloader: loading kernel modules from /etc/modules.d/*
[ 11.892488] exFAT: Version 1.2.9
[ 11.920250] ntfs: driver 2.1.32 [Flags: R/O MODULE].
[ 11.975822] fuse init (API version 7.23)
[ 11.995217] Loading modules backported from Linux version wt-2017-01-31-0-ge882dff19e7f
[ 12.003580] Backport generated by backports.git backports-20160324-13-g24da7d3c
[ 12.019126] nf_conntrack version 0.5.0 (439 buckets, 1756 max)
[ 12.051082] wireguard: WireGuard 0.0.20180519 loaded. See www.wireguard.com for information.
[ 12.059809] wireguard: Copyright (C) 2015-2018 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
[ 12.092373] xt_time: kernel timezone is -0000
[ 12.126705] ip_tables: (C) 2000-2006 Netfilter Core Team
[ 12.243983] ath: EEPROM regdomain: 0x0
[ 12.244008] ath: EEPROM indicates default country code should be used
[ 12.244018] ath: doing EEPROM country->regdmn map search
[ 12.244042] ath: country maps to regdmn code: 0x3a
[ 12.244054] ath: Country alpha2 being used: US
[ 12.244064] ath: Regpair used: 0x3a
[ 12.257914] ieee80211 phy0: Selected rate control algorithm 'minstrel_ht'
[ 12.264898] ieee80211 phy0: Atheros AR9340 Rev:3 mem=0xb8100000, irq=47
[ 12.320567] kmodloader: done loading kernel modules from /etc/modules.d/*
[ 12.342813] random: nonblocking pool is initialized
[ 46.686773] device eth1 entered promiscuous mode
[ 46.725758] IPv6: ADDRCONF(NETDEV_UP): br-lan: link is not ready
[ 46.833953] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready
[ 52.832367] ath: EEPROM regdomain: 0x81ca
[ 52.836560] ath: EEPROM indicates we should expect a country code
[ 52.842903] ath: doing EEPROM country->regdmn map search
[ 52.848392] ath: country maps to regdmn code: 0x5d
[ 52.853354] ath: Country alpha2 being used: MY
[ 52.857940] ath: Regpair used: 0x5d
[ 52.861559] ath: regdomain 0x81ca dynamically updated by user
[ 61.310398] IPv6: ADDRCONF(NETDEV_UP): TP-LINK_659534: link is not ready
[ 61.396470] device TP-LINK_659534 entered promiscuous mode
[ 67.239255] IPv6: ADDRCONF(NETDEV_UP): wlan0: link is not ready
[ 70.394615] wlan0: authenticate with d8:5b:2a:95:ed:9b
[ 70.417680] wlan0: send auth to d8:5b:2a:95:ed:9b (try 1/3)
[ 70.433811] wlan0: authenticated
[ 70.510234] wlan0: associate with d8:5b:2a:95:ed:9b (try 1/3)
[ 70.529159] wlan0: RX AssocResp from d8:5b:2a:95:ed:9b (capab=0x411 status=0 aid=2)
[ 70.537437] wlan0: associated
[ 70.540718] IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready
[ 70.625434] wlan0: Limiting TX power to 20 (20 - 0) dBm as advertised by d8:5b:2a:95:ed:9b
[ 71.924100] IPv6: ADDRCONF(NETDEV_CHANGE): TP-LINK_659534: link becomes ready
[ 71.931745] br-lan: port 2(TP-LINK_659534) entered forwarding state
[ 71.938273] br-lan: port 2(TP-LINK_659534) entered forwarding state
[ 71.995703] IPv6: ADDRCONF(NETDEV_CHANGE): br-lan: link becomes ready
[ 73.930110] br-lan: port 2(TP-LINK_659534) entered forwarding state