Xiaomi router hd(r3d), which mtd to use to flash openwrt?

Hi guys, I got a Xiaomi HD router and I want to install the latest openwrt ROM on it, but I don't know which mtd dev to use, router OS info(it's a OS derived from openwrt):
Linux XiaoQiang 3.4.103 #1 MiWiFi-R3D-2.25.52 SMP PREEMPT Fri Aug 18 19:19:30 CST 2017 armv7l GNU/Linux

(mtd write xxx-squashfs-sysupgrade.bin xxx, which mtd to use?):

cat /proc/mtd

dev: size erasesize name

mtd0: 00080000 00020000 "Bdata"

mtd1: 00080000 00020000 "crash"

mtd2: 00080000 00020000 "crash_syslog"

mtd3: 00080000 00020000 "rsvd"

mtd4: 00400000 00020000 "kernel0"

mtd5: 00400000 00020000 "kernel1"

mtd6: 02800000 00020000 "rootfs0"

mtd7: 02800000 00020000 "rootfs1"

mtd8: 0a000000 00020000 "overlay"

mtd9: 00040000 00020000 "SBL1"

mtd10: 00080000 00020000 "MIBIB"

mtd11: 00080000 00020000 "SBL2"

mtd12: 00080000 00020000 "SBL3"

mtd13: 00080000 00020000 "DDRCONFIG"

mtd14: 00080000 00020000 "SSD"

mtd15: 00080000 00020000 "TZ"

mtd16: 00080000 00020000 "RPM"

mtd17: 00100000 00020000 "APPSBL"

mtd18: 00080000 00020000 "APPSBLENV"

mtd19: 00080000 00020000 "ART"

mtd20: 00010000 00001000 "m25p80"

mtd21: 09302000 0001f000 "data"

Here is the details of the router:
https://wikidevi.com/wiki/Xiaomi_MiWiFi_HD

CPU: Qualcomm  IPQ8064 ( 1.4 GHz ,2 cores)
WI1 chip1: Qualcomm Atheros  QCA9980
ETH chip1:   Qualcomm  IPQ8064
Switch: Qualcomm Atheros  QCA8337

I also got an xiaomi router mini which has these mtds:

cat /proc/mtd

dev:    size   erasesize  name

mtd0: 01000000 00010000 "ALL"

mtd1: 00030000 00010000 "Bootloader"

mtd2: 00010000 00010000 "Config"

mtd3: 00010000 00010000 "Factory"

mtd4: 00c80000 00010000 "OS1"

mtd5: 00b178a7 00010000 "rootfs"

mtd6: 00200000 00010000 "OS2"

mtd7: 00100000 00010000 "overlay"

mtd8: 00010000 00010000 "crash"

mtd9: 00010000 00010000 "reserved"

mtd10: 00010000 00010000 "Bdata"

and I can flash a ROM successfully with the following command:
root@XiaoQiang:/tmp# mtd -r write xxx-mt7620-xiaomi-mini-squashfs-sysupgrade-r1696-20151122.bin OS1