Ignore power down event with disable_powersave=1 module option

When the chip is in lower power state, it listens only for the packets
which destination MAC match device's MAC address.
Incoming broadcast and multicast packets, which MAC does not equal
to the device MAC, gets dropped.

This breaks mDNS and other protocols.

Power saving works as follows: the chip sends PWR_DOWN event to the
kernel module when it's ready to go into lower state, and if the kernel
is also ready (nothing in tx queue), it replies with ACK.

Add disable_powersave=1 kernel option to ignore PWR_DOWN event completely
to reliably accept multicast, at the cost of +0.4W

Link: orangepi-xunlong/linux-orangepi#98 (comment)

Author: ValdikSS

unisocwifi/cmdevt.c

@@ -3257,6 +3257,12 @@ static void sprdwl_event_fw_power_down(struct sprdwl_vif *vif, u8 *data, u16 len
 {
 	struct sprdwl_work *misc_work;
 
+	/* When powersave is disabled, silently ignore the firmware's sleep
+	 * request. Responding with value=0 causes the firmware to immediately
+	 * re-send WIFI_EVENT_FW_PWR_DOWN in a tight loop, burning CPU. */
+	if (disable_powersave)
+		return;
+
 	misc_work = sprdwl_alloc_work(0);
 	if (!misc_work) {
 		wl_err("%s out of memory\n", __func__);

unisocwifi/cmdevt.h

@@ -75,6 +75,7 @@
 #define SPRDWL_11V_ALL_FEATURE          0xFFFF
 
 extern unsigned int wfa_cap;
+extern unsigned int disable_powersave;
 enum SPRDWL_CMD_LIST {
 	WIFI_CMD_MIN = 0,
 	WIFI_CMD_ERR = WIFI_CMD_MIN,

unisocwifi/main.c

@@ -1658,6 +1658,10 @@ unsigned int wfa_cap;
 module_param(wfa_cap, uint, 0000);
 MODULE_PARM_DESC(wfa_cap, "set capability for WFA test");
 
+unsigned int disable_powersave;
+module_param(disable_powersave, uint, 0000);
+MODULE_PARM_DESC(disable_powersave, "Disable firmware power save mode (0=default, 1=ignore EVENT_PWR_DOWN)");
+
 unsigned int tcp_ack_drop_cnt = SPRDWL_TCP_ACK_DROP_CNT;
 /* Maybe you need S_IRUGO | S_IWUSR for debug */
 module_param(tcp_ack_drop_cnt, uint, 0000);