wcn36xx: Pad TIM PVM if needed

The wcn36xx FW expects a fixed size TIM PVM in the beacon template. If
supplied with a shorter than expected PVM it will overwrite the IE
following the TIM.

Squashed with fix from Jason Mobarak <jam@cozybit.com>:
Patch "wcn36xx: Pad TIM PVM if needed" has caused a regression in mesh
beaconing.  The field tim_off is always 0 for mesh mode, and thus
pvm_len (referring to the TIM length field) and pad are both incorrectly
calculated.  Thus, msg_body.beacon_length is incorrectly calculated for
mesh mode. Fix this.

Signed-off-by: Pontus Fuchs <pontus.fuchs@gmail.com>
Signed-off-by: Jason Mobarak <jam@cozybit.com>
[bjorn: squashed in Jason's fixup]
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

2 files changed, 28 insertions, 2 deletions

diff --git a/drivers/net/wireless/ath/wcn36xx/hal.h b/drivers/net/wireless/ath/wcn36xx/hal.h
index d713204f755d..3af16cba3d12 100644
--- a/drivers/net/wireless/ath/wcn36xx/hal.h
+++ b/drivers/net/wireless/ath/wcn36xx/hal.h
@@ -54,6 +54,9 @@
 /* Default Beacon template size */
 #define BEACON_TEMPLATE_SIZE 0x180
 
+/* Minimum PVM size that the FW expects. See comment in smd.c for details. */
+#define TIM_MIN_PVM_SIZE 6
+
 /* Param Change Bitmap sent to HAL */
 #define PARAM_BCN_INTERVAL_CHANGED                      (1 << 0)
 #define PARAM_SHORT_PREAMBLE_CHANGED                 (1 << 1)
diff --git a/drivers/net/wireless/ath/wcn36xx/smd.c b/drivers/net/wireless/ath/wcn36xx/smd.c
index ff3ed2461a69..089a7e445cd6 100644
--- a/drivers/net/wireless/ath/wcn36xx/smd.c
+++ b/drivers/net/wireless/ath/wcn36xx/smd.c
@@ -1375,12 +1375,19 @@ int wcn36xx_smd_send_beacon(struct wcn36xx *wcn, struct ieee80211_vif *vif,
                             u16 p2p_off)
 {
         struct wcn36xx_hal_send_beacon_req_msg msg_body;
-        int ret = 0;
+        int ret = 0, pad, pvm_len;
 
         mutex_lock(&wcn->hal_mutex);
         INIT_HAL_MSG(msg_body, WCN36XX_HAL_SEND_BEACON_REQ);
 
-        msg_body.beacon_length = skb_beacon->len;
+        pvm_len = skb_beacon->data[tim_off + 1] - 3;
+        pad = TIM_MIN_PVM_SIZE - pvm_len;
+
+        /* Padding is irrelevant to mesh mode since tim_off is always 0. */
+        if (vif->type == NL80211_IFTYPE_MESH_POINT)
+                pad = 0;
+
+        msg_body.beacon_length = skb_beacon->len + pad;
         /* TODO need to find out why + 6 is needed */
         msg_body.beacon_length6 = msg_body.beacon_length + 6;
 
@@ -1393,6 +1400,22 @@ int wcn36xx_smd_send_beacon(struct wcn36xx *wcn, struct ieee80211_vif *vif,
         memcpy(msg_body.beacon, skb_beacon->data, skb_beacon->len);
         memcpy(msg_body.bssid, vif->addr, ETH_ALEN);
 
+        if (pad > 0) {
+                /*
+                 * The wcn36xx FW has a fixed size for the PVM in the TIM. If
+                 * given the beacon template from mac80211 with a PVM shorter
+                 * than the FW expectes it will overwrite the data after the
+                 * TIM.
+                 */
+                wcn36xx_dbg(WCN36XX_DBG_HAL, "Pad TIM PVM. %d bytes at %d\n",
+                            pad, pvm_len);
+                memmove(&msg_body.beacon[tim_off + 5 + pvm_len + pad],
+                        &msg_body.beacon[tim_off + 5 + pvm_len],
+                        skb_beacon->len - (tim_off + 5 + pvm_len));
+                memset(&msg_body.beacon[tim_off + 5 + pvm_len], 0, pad);
+                msg_body.beacon[tim_off + 1] += pad;
+        }
+
         /* TODO need to find out why this is needed? */
         if (vif->type == NL80211_IFTYPE_MESH_POINT)
                 /* mesh beacon don't need this, so push further down */