Wr940v6 panic kernel

greetiing all.
first of all great work openwrt/lede team and all contribuators.keep it up.
i am new here.
after tftp update i got bootloop:

TFTP from server 192.168.0.66; our IP address is 192.168.0.86
Filename 'wr940nv6_tp_recovery.bin'.
Load address: 0x80800000
Loading: T T T #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         ######################################################
done
Bytes transferred = 3932160 (3c0000 hex)
original_product_id = 155189254, original_product_ver = 1
recovery_product_id = 155189254, recovery_product_ver = 1
Firmware recovery: product id verify sucess!
Firmware recovery: filesize = 0x3c0000.
Erasing flash...
First 0x2 last 0x3d sector size 0x10000
  61
Erased 60 sectors
Copy to Flash... write addr: 9f020000
done

U-Boot 1.1.4 (Jan 19 2018 - 16:26:12)

ap151 - Dragonfly 1.0

DRAM:  32 MB
Top of RAM usable for U-Boot at: 82000000
Reserving 141k for U-Boot at: 81fdc000
Reserving 192k for malloc() at: 81fac000
Reserving 44 Bytes for Board Info at: 81fabfd4
Reserving 36 Bytes for Global Data at: 81fabfb0
Reserving 128k for boot params() at: 81f8bfb0
Stack Pointer at: 81f8bf98
Now running in RAM - U-Boot at: 81fdc000
Flash Manuf Id 0x1c, DeviceId0 0x70, DeviceId1 0x16
flash size 4MB, sector count = 64
Flash:  4 MB
Using default environment

In:    serial
Out:   serial
Err:   serial
Net:   ath_gmac_enet_initialize...
No valid address in Flash. Using fixed address
No valid address in Flash. Using fixed address
ath_gmac_enet_initialize: reset mask:c02200
Dragonfly----> S27 PHY *
: cfg1 0x80000000 cfg2 0x7114
eth0: 00:03:7f:09:0b:ad
athrs27_phy_setup ATHR_PHY_CONTROL 4 :1000
athrs27_phy_setup ATHR_PHY_SPEC_STAUS 4 :10
eth0 up
ATHRS27: resetting s27
ATHRS27: s27 reset done
: cfg1 0x800c0000 cfg2 0x7214
eth1: 00:03:7f:09:0b:ad
athrs27_phy_setup ATHR_PHY_CONTROL 0 :1000
athrs27_phy_setup ATHR_PHY_SPEC_STAUS 0 :10
athrs27_phy_setup ATHR_PHY_CONTROL 1 :1000
athrs27_phy_setup ATHR_PHY_SPEC_STAUS 1 :10
athrs27_phy_setup ATHR_PHY_CONTROL 2 :1000
athrs27_phy_setup ATHR_PHY_SPEC_STAUS 2 :10
athrs27_phy_setup ATHR_PHY_CONTROL 3 :1000
athrs27_phy_setup ATHR_PHY_SPEC_STAUS 3 :10
eth1 up
eth0, eth1
Setting 0x181162c0 to 0x82
is_auto_upload_firmware=0
Autobooting in 1 seconds
## Booting image at 9f020000 ...
   Uncompressing Kernel Image ... OK
No initrd
## Transferring control to Linux (at address 80060000) ...
## Giving linux memsize in bytes, 33554432

Starting kernel ...

[    0.000000] Linux version 4.9.214 (buildbot@0d27b924961c) (gcc version 7.3.0 (OpenWrt GCC 7.3.0 r7989-82fbd85747) ) #0 Thu Feb 27 21:25:59 2020
[    0.000000] bootconsole [early0] enabled
[    0.000000] CPU0 revision is: 00019750 (MIPS 74Kc)
[    0.000000] SoC: Qualcomm Atheros TP9343 rev 0
[    0.000000] Determined physical RAM map:
[    0.000000]  memory: 02000000 @ 00000000 (usable)
[    0.000000] Initrd not found or empty - disabling initrd
[    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] 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] Built 1 zonelists in Zone order, mobility grouping on.  Total pages: 8128
[    0.000000] Kernel command line:  board=TL-WR940N-v6  console=ttyS0,115200 rootfstype=squashfs 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: 27604K/32768K available (3408K kernel code, 167K rwdata, 424K rodata, 216K init, 211K bss, 5164K 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:750.000MHz, DDR:400.000MHz, AHB:250.000MHz, Ref:25.000MHz
[    0.000000] clocksource: MIPS: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 5096694524 ns
[    0.000009] sched_clock: 32 bits at 375MHz, resolution 2ns, wraps every 5726622718ns
[    0.008257] Calibrating delay loop... 373.55 BogoMIPS (lpj=1867776)
[    0.071138] pid_max: default: 32768 minimum: 301
[    0.076112] Mount-cache hash table entries: 1024 (order: 0, 4096 bytes)
[    0.083096] Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes)
[    0.093507] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112604462750000 ns
[    0.103915] futex hash table entries: 256 (order: -1, 3072 bytes)
[    0.111667] NET: Registered protocol family 16
[    0.117949] MIPS: machine is TP-LINK TL-WR940N v6
[    0.613391] clocksource: Switched to clocksource MIPS
[    0.619838] NET: Registered protocol family 2
[    0.625389] TCP established hash table entries: 1024 (order: 0, 4096 bytes)
[    0.632742] TCP bind hash table entries: 1024 (order: 0, 4096 bytes)
[    0.639506] TCP: Hash tables configured (established 1024 bind 1024)
[    0.646329] UDP hash table entries: 256 (order: 0, 4096 bytes)
[    0.652503] UDP-Lite hash table entries: 256 (order: 0, 4096 bytes)
[    0.659435] NET: Registered protocol family 1
[    0.668076] Crashlog allocated RAM at address 0x1f00000
[    0.674941] workingset: timestamp_bits=30 max_order=13 bucket_order=0
[    0.688178] squashfs: version 4.0 (2009/01/31) Phillip Lougher
[    0.694368] jffs2: version 2.2 (NAND) (SUMMARY) (LZMA) (RTIME) (CMODE_PRIORITY) (c) 2001-2006 Red Hat, Inc.
[    0.715194] io scheduler noop registered
[    0.719332] io scheduler deadline registered (default)
[    0.725232] Serial: 8250/16550 driver, 16 ports, IRQ sharing enabled
[    0.734508] console [ttyS0] disabled
[    0.758384] serial8250.0: ttyS0 at MMIO 0x18020000 (irq = 11, base_baud = 1562500) is a 16550A
[    0.767496] console [ttyS0] enabled
[    0.767496] console [ttyS0] enabled
[    0.775055] bootconsole [early0] disabled
[    0.775055] bootconsole [early0] disabled
[    0.790439] m25p80 spi0.0: unrecognized JEDEC id bytes: 1c, 70, 16
[    0.797907] libphy: Fixed MDIO Bus: probed
[    0.821465] libphy: ag71xx_mdio: probed
[    1.455483] ag71xx ag71xx.0: connected to PHY at ag71xx-mdio.1:04 [uid=004dd042, driver=Generic PHY]
[    1.465610] eth0: Atheros AG71xx at 0xb9000000, irq 4, mode:MII
[    2.095257] ag71xx-mdio.1: Found an AR934X built-in switch
[    2.147527] eth1: Atheros AG71xx at 0xba000000, irq 5, mode:GMII
[    2.155472] NET: Registered protocol family 10
[    2.164242] NET: Registered protocol family 17
[    2.168892] bridge: filtering via arp/ip/ip6tables is no longer available by default. Update your scripts to load br_netfilter if you need this.
[    2.182427] 8021q: 802.1Q VLAN Support v1.8
[    2.188704] hctosys: unable to open rtc device (rtc0)
[    2.194773] VFS: Cannot open root device "(null)" or unknown-block(0,0): error -6
[    2.202504] Please append a correct "root=" boot option; here are the available partitions:
[    2.211186] Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)
[    2.220244] Rebooting in 1 seconds..

it was 2 brand new units ,Firmware Version:
3.19.1 Build 180119 Rel.59618n
Hardware Version:
WR940N v6 00000000
normal booting with orignal tplink fimware.
I also trayed varied openwrt versions.
some of stop at booting linux....
and finaly ddwrt boots fine,but i m not comfortable with it.
its maybe somthing wrong with spi-nor driver ic support (EN25QH32) .([ 0.790439] m25p80 spi0.0: unrecognized JEDEC id bytes: 1c, 70, 16)
any one have a clue about it ?

Yes unsupported flash chip. They must have changed the chip type during production.
This is fixable by adding the JEDEC ID to the flash driver and rebuilding, but still it's a 4/32 memory.

Thanks for your quick and clear answer .
as cheap as they are ;there still be in production meaning wide spread use .
but is this in range for a newbie
any simples steps?

thank you.