Tp-link archer C6U v1 (RU)

[bolvan]

I've just bought subj hoping it would be easy to install openwrt. Not so easy
First, stock UI complains on openwrt factory image and refuses to flash it
I connected UART and forced u-boot webserver
Upload succeeds but nothing indicates flashing was done. It isn't. Nothing changed after reboot
Then I tried uploading RU and EU stock firmwares with the same result. Nothing

After some experiments I succeeded to tftp boot openwrt ramdisk image and it works
but sysupgrade does not work from there. Stock u-boot complains CRC error

If someone has this device EU version I'd appreciate if you post full SPI dump here
(or u-boot + config + tplink mtd partitions)
I guess hardware is the same and my RU can easily become EU

Also I could not figure out memory mapped SPI address to cp.b to. It would simplify things a lot
For now i'm builing custom openwrt ramdisk with readonly-removed patched dts

for reference, stock mtd layout :

mtd0: 00040000 00010000 "uboot" 00000000
mtd1: 00200000 00010000 "uImage" 00040000
mtd2: 00db0000 00010000 "rootfs" 00240000
mtd3: 00010000 00010000 "ART" 00ff0000

openwrt mtd layout:

mtd0: 00040000 00010000 "u-boot"
mtd1: 00f60000 00010000 "firmware"
mtd2: 002448e6 00010000 "kernel"
mtd3: 00d1b71a 00010000 "rootfs"
mtd4: 00980000 00010000 "rootfs_data"
mtd5: 00010000 00010000 "config"
mtd6: 00040000 00010000 "tplink"
mtd7: 00010000 00010000 "radio"

[bolvan]

Actually, despite of russian UI firmware was US and that's the reason why it failed to update
I checked serial output while upgrading in stock firmware (not failsafe u-boot web server) and found this :

upgrade firmware...
Reading Partition Table from NVRAM ... OK
Parsing Partition Table ... OK
file_len:15941879
fw_type_name : Cloud 
cloud CheckUpgradeFile : 303
md5 verify ok!
[Error]sysmgr_proinfo_buildStruct():  670 @ unknown id(device_name), skip it.
[Error]sysmgr_proinfo_buildStruct():  670 @ unknown id(country), skip it.
--------------------------------------------------------------------
      vendorName : TP-LINK
       vendorUrl : www.tp-link.com
     productName : Archer C6U
 productLanguage : US
       productId : 00060003
      productVer : ff010000
       specialId : 52550000
            hwId : 777A3465FACD995BB4E1302DB813F637
           oemId : FD94DDBB03861EE1E01B2A03AF337CE1
--------------------------------------------------------------------
[Error]sysmgr_cfg_checkSupportList():  973 @ specialId 45550000 NOT Match.
Firmwave not supports, check failed.
[NM_Error](nm_checkUpdateContent) 01051: hardware version not support
[NM_Error](nm_buildUpgradeStruct) 01161: checkUpdateContent failed.
check firmware error!
[NM_Error](nvrammanager_checkUpgradeFile) 00784: check firmware file failed!

[NM_Error](main) 01160: firmware upgrade file check error 

firmware check fail
upgrade false

I changed specialId to 52550000 in tplink-safeloader.c, rebuilt openwrt and it all worked.
I will never need that hack again because now openwrt sysupgrade should work
Problem is solved

If someone needs US/RU compatible image I can share