REG_HMTFR
rtl8xxxu_write8(priv, REG_HMTFR + 3, 0x20);
val8 = rtl8xxxu_read8(priv, REG_HMTFR);
rtl8xxxu_write8(priv, REG_HMTFR, 0x0f);
rtl8xxxu_write8(priv, REG_HMTFR + 3, 0x20);
val8 = rtl8xxxu_read8(priv, REG_HMTFR);