I have 2 TP-Link WDR4300v1 routers (versions 1.0 and 1.2, but they do not differ in hardware). It uses 2 wifi-chips AR9344 and AR9580. I compile myself from snapshots firmware for it.
Latest snapshots builds of ar71xx (12297, 12320) doing something terrible with my ART-partition (mtd4). When i recently upgrade to this builds i lost all wifi (2.4 and 5GHz). And this is not config/wireless problem, cause i do factory reset. In dmesg log it looks like:
[ 9.662487] ath: phy0: Unable to initialize hardware; initialization status: -5 [ 9.864421] ath: phy1: Unable to initialize hardware; initialization status: -5
I found this to be caused by nulling the mtd ART section. Then I compiled a new firmware on 12320 with kmod-mtd-rw support. Flashed one of the ready-made ART sections from the site https://github.com/gwlim/art-radio/tree/master/AR9344-Tested_on_WDR4300 with these commands:
insmod mtd-rw i_want_a_brick=1 mtd unlock art mtd -r write /tmp/art.backup art
Wifi began to work, but after a reboot, it disappeared again and the errors indicated above appeared.
Then I acted more cunningly - I flashed 12320, then I flashed the ART section without rebooting (mtd write without -r) and then I flashed the old build 12162.
And everything works as it should, plus I now have overclocked power parameters and an increased number of channels on the 2.4 and 5 GHz bands.
Additionally, I know that it is now recommended to use the ath79 (DTS) platform for the WDR4300, however, 5GHz does not work there, even with the corrected ART section. I suspect that the matter is in new drivers that are looking for parameters in the ART section in a different place than ar71xx.
My builds can be taken here: http://openwrt.do2.pw/my_builds/firmware/
If the ART section is damaged, firmware rollbacks to the stock will not help, nor rollbacks to previous versions of OpenWRT. Only rewriting the MTD section of ART will help.