iwlwifi: do not set tx power when channel is changing

Mac80211 can request for tx power and channel change in one ->config
call. If that happens, *_send_tx_power functions will try to setup tx
power for old channel, what can be not correct because we already change
the band. I.e  error  "Failed to get channel info for channel 140 [0]",
can be printed frequently when operating in software scanning mode.
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Acked-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/iwlwifi/iwl-3945.c

@@ -1890,7 +1890,7 @@ int iwl3945_commit_rxon(struct iwl_priv *priv, struct iwl_rxon_context *ctx)
 
 	/* If we issue a new RXON command which required a tune then we must
 	 * send a new TXPOWER command or we won't be able to Tx any frames */
-	rc = priv->cfg->ops->lib->send_tx_power(priv);
+	rc = iwl_set_tx_power(priv, priv->tx_power_next, true);
 	if (rc) {
 		IWL_ERR(priv, "Error setting Tx power (%d).\n", rc);
 		return rc;

drivers/net/wireless/iwlwifi/iwl-4965.c

@@ -1571,7 +1571,7 @@ static int iwl4965_commit_rxon(struct iwl_priv *priv, struct iwl_rxon_context *c
 
 	/* If we issue a new RXON command which required a tune then we must
 	 * send a new TXPOWER command or we won't be able to Tx any frames */
-	ret = iwl_set_tx_power(priv, priv->tx_power_user_lmt, true);
+	ret = iwl_set_tx_power(priv, priv->tx_power_next, true);
 	if (ret) {
 		IWL_ERR(priv, "Error sending TX power (%d)\n", ret);
 		return ret;

drivers/net/wireless/iwlwifi/iwl-agn-rxon.c

@@ -316,10 +316,9 @@ int iwlagn_commit_rxon(struct iwl_priv *priv, struct iwl_rxon_context *ctx)
 	 * If we issue a new RXON command which required a tune then we must
 	 * send a new TXPOWER command or we won't be able to Tx any frames.
 	 *
-	 * FIXME: which RXON requires a tune? Can we optimise this out in
-	 *        some cases?
+	 * It's expected we set power here if channel is changing.
 	 */
-	ret = iwl_set_tx_power(priv, priv->tx_power_user_lmt, true);
+	ret = iwl_set_tx_power(priv, priv->tx_power_next, true);
 	if (ret) {
 		IWL_ERR(priv, "Error sending TX power (%d)\n", ret);
 		return ret;

drivers/net/wireless/iwlwifi/iwl-core.c

@@ -1162,6 +1162,8 @@ int iwl_set_tx_power(struct iwl_priv *priv, s8 tx_power, bool force)
 {
 	int ret;
 	s8 prev_tx_power;
+	bool defer;
+	struct iwl_rxon_context *ctx = &priv->contexts[IWL_RXON_CTX_BSS];
 
 	lockdep_assert_held(&priv->mutex);
 
@@ -1189,10 +1191,15 @@ int iwl_set_tx_power(struct iwl_priv *priv, s8 tx_power, bool force)
 	if (!iwl_is_ready_rf(priv))
 		return -EIO;
 
-	/* scan complete use tx_power_next, need to be updated */
+	/* scan complete and commit_rxon use tx_power_next value,
+	 * it always need to be updated for newest request */
 	priv->tx_power_next = tx_power;
-	if (test_bit(STATUS_SCANNING, &priv->status) && !force) {
-		IWL_DEBUG_INFO(priv, "Deferring tx power set while scanning\n");
+
+	/* do not set tx power when scanning or channel changing */
+	defer = test_bit(STATUS_SCANNING, &priv->status) ||
+		memcmp(&ctx->active, &ctx->staging, sizeof(ctx->staging));
+	if (defer && !force) {
+		IWL_DEBUG_INFO(priv, "Deferring tx power set\n");
 		return 0;
 	}