net: wireless: bcmdhd: Change DTIM skip policy in suspend

	issue : WiFi continuously disconnects
	Root cause :
	Sometimes we got link down event due to beacon
	lost when device goes to suspend.
	This problem sometimes happens in case that DTIM is 3 and beacon
	100ms because we wake up on 900ms (100ms * 3 * 3) during
	suspend.
	This value(900ms) is too big to STA for sync up with AP time.
	This causes STA out of sync for time with the AP.
	Eventually STA got lost of beacon during long time (4secs).

	Solution :
	If the total dtim skip interval (beacon_interval *
	DTIM * 3) is greater than 300ms, we will not extend DTIM to DTIM
	* 3.
	Instead of that, we will use original value (DTIM) for wake up
	in suspend.
	Bug : 1343127 WiFi continuously disconnects

Signed-off-by: Ecco Park <eccopark@broadcom.com>

Change-Id: I6d89bd1c56127befe4d9606869396ee25b7911ef

2 files changed, 19 insertions, 12 deletions

diff --git a/drivers/net/wireless/bcmdhd/dhd.h b/drivers/net/wireless/bcmdhd/dhd.h
index 89df67e..f8cee0a 100644
--- a/drivers/net/wireless/bcmdhd/dhd.h
+++ b/drivers/net/wireless/bcmdhd/dhd.h
@@ -789,7 +789,9 @@ extern uint dhd_force_tx_queueing;
 #endif
 #endif /* WLTDLS */
 
-#define MAX_DTIM_SKIP_BEACON_ITERVAL	100 /* max allowed associated AP beacon for dtim skip */
+#define MAX_DTIM_SKIP_BEACON_INTERVAL	100 /* max allowed associated AP beacon for DTIM skip */
+#define MAX_DTIM_ALLOWED_INTERVAL 300 /* max allowed total beacon interval for DTIM skip */
+#define NO_DTIM_SKIP 1
 
 #ifdef SDTEST
 /* Echo packet generator (SDIO), pkts/s */
diff --git a/drivers/net/wireless/bcmdhd/dhd_common.c b/drivers/net/wireless/bcmdhd/dhd_common.c
index 9fad303..c3e19b2 100644
--- a/drivers/net/wireless/bcmdhd/dhd_common.c
+++ b/drivers/net/wireless/bcmdhd/dhd_common.c
@@ -1863,9 +1863,9 @@ dhd_get_suspend_bcn_li_dtim(dhd_pub_t *dhd)
 {
 	int bcn_li_dtim = 1; /* deafult no dtim skip setting */
 	int ret = -1;
-	int dtim_assoc = 0;
+	int dtim_period = 0;
 	int ap_beacon = 0;
-
+	int allowed_skip_dtim_cnt = 0;
 	/* Check if associated */
 	if (dhd_is_associated(dhd, NULL, NULL) == FALSE) {
 		DHD_TRACE(("%s NOT assoc ret %d\n", __FUNCTION__, ret));
@@ -1880,20 +1880,20 @@ dhd_get_suspend_bcn_li_dtim(dhd_pub_t *dhd)
 	}
 
 	/* if associated APs Beacon more  that 100msec do no dtim skip */
-	if (ap_beacon > MAX_DTIM_SKIP_BEACON_ITERVAL) {
+	if (ap_beacon > MAX_DTIM_SKIP_BEACON_INTERVAL) {
 		DHD_ERROR(("%s NO dtim skip for AP with beacon %d ms\n", __FUNCTION__, ap_beacon));
 		goto exit;
 	}
 
 	/* read associated ap's dtim setup */
 	if ((ret = dhd_wl_ioctl_cmd(dhd, WLC_GET_DTIMPRD,
-		&dtim_assoc, sizeof(dtim_assoc), FALSE, 0)) < 0) {
+		&dtim_period, sizeof(dtim_period), FALSE, 0)) < 0) {
 		DHD_ERROR(("%s failed code %d\n", __FUNCTION__, ret));
 		goto exit;
 	}
 
 	/* if not assocated just eixt */
-	if (dtim_assoc == 0) {
+	if (dtim_period == 0) {
 		goto exit;
 	}
 
@@ -1901,22 +1901,27 @@ dhd_get_suspend_bcn_li_dtim(dhd_pub_t *dhd)
 	bcn_li_dtim = dhd->suspend_bcn_li_dtim;
 
 	/* check if sta listen interval fits into AP dtim */
-	if (dtim_assoc > CUSTOM_LISTEN_INTERVAL) {
+	if (dtim_period > CUSTOM_LISTEN_INTERVAL) {
 		/* AP DTIM to big for our Listen Interval : no dtim skiping */
-		bcn_li_dtim = 1;
+		bcn_li_dtim = NO_DTIM_SKIP;
 		DHD_ERROR(("%s DTIM=%d > Listen=%d : too big ...\n",
-			__FUNCTION__, dtim_assoc, CUSTOM_LISTEN_INTERVAL));
+			__FUNCTION__, dtim_period, CUSTOM_LISTEN_INTERVAL));
 		goto exit;
 	}
 
-	if ((bcn_li_dtim * dtim_assoc) > CUSTOM_LISTEN_INTERVAL) {
+	if ((dtim_period * ap_beacon * bcn_li_dtim) > MAX_DTIM_ALLOWED_INTERVAL) {
+		 allowed_skip_dtim_cnt = MAX_DTIM_ALLOWED_INTERVAL / (dtim_period * ap_beacon);
+		 bcn_li_dtim = (allowed_skip_dtim_cnt != 0) ? allowed_skip_dtim_cnt : NO_DTIM_SKIP;
+	}
+
+	if ((bcn_li_dtim * dtim_period) > CUSTOM_LISTEN_INTERVAL) {
 		/* Round up dtim_skip to fit into STAs Listen Interval */
-		bcn_li_dtim = (int)(CUSTOM_LISTEN_INTERVAL / dtim_assoc);
+		bcn_li_dtim = (int)(CUSTOM_LISTEN_INTERVAL / dtim_period);
 		DHD_TRACE(("%s agjust dtim_skip as %d\n", __FUNCTION__, bcn_li_dtim));
 	}
 
 	DHD_ERROR(("%s beacon=%d bcn_li_dtim=%d DTIM=%d Listen=%d\n",
-		__FUNCTION__, ap_beacon, bcn_li_dtim, dtim_assoc, CUSTOM_LISTEN_INTERVAL));
+		__FUNCTION__, ap_beacon, bcn_li_dtim, dtim_period, CUSTOM_LISTEN_INTERVAL));
 
 exit:
 	return bcn_li_dtim;