Who are using openwrt on device with separate pci Atheros card (not a SoC!) and ath9k driver in MIMO mode at 2.4 802.11n -- which maximum speed do you get?
I have Unielec 7621-06, MTK7621AT chipset, 512 RAM, 64 NAND,and Atheros AR9287 mini pci-e card.
In case of enable hwcrypt I have up to 65 mbit/s but connection losts very often for any client (Androind, Windows, TV).
In case of disablng hwcrypt connection became much more stable but speed does not increase 25-30 mbit/s