iwlwifi: mvm: don't change band on bound PHY contexts

When we have a P2P Device active, we attempt to only change the
PHY context it uses when we get a new remain-on-channel, if the
P2P Device is the only user of the PHY context.

This is fine if we're switching within a band, but if we're
switching bands then the switch implies a removal and re-add
of the PHY context, which isn't permitted by the firmware while
it's bound to an interface.

Fix the code to skip the unbind/release/... cycle only if the
band doesn't change (or we have old devices that can switch the
band on the fly as well.)
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20210612142637.e9ac313f70f3.I713b9d109957df7e7d9ed0861d5377ce3f8fccd3@changeidSigned-off-by: Luca Coelho <luciano.coelho@intel.com>

drivers/net/wireless/intel/iwlwifi/mvm/mac80211.c

@@ -3800,6 +3800,7 @@ static int iwl_mvm_roc(struct ieee80211_hw *hw,
 	struct iwl_mvm_vif *mvmvif = iwl_mvm_vif_from_mac80211(vif);
 	struct cfg80211_chan_def chandef;
 	struct iwl_mvm_phy_ctxt *phy_ctxt;
+	bool band_change_removal;
 	int ret, i;
 
 	IWL_DEBUG_MAC80211(mvm, "enter (%d, %d, %d)\n", channel->hw_value,
@@ -3880,19 +3881,30 @@ static int iwl_mvm_roc(struct ieee80211_hw *hw,
 	cfg80211_chandef_create(&chandef, channel, NL80211_CHAN_NO_HT);
 
 	/*
-	 * Change the PHY context configuration as it is currently referenced
-	 * only by the P2P Device MAC
+	 * Check if the remain-on-channel is on a different band and that
+	 * requires context removal, see iwl_mvm_phy_ctxt_changed(). If
+	 * so, we'll need to release and then re-configure here, since we
+	 * must not remove a PHY context that's part of a binding.
 	 */
-	if (mvmvif->phy_ctxt->ref == 1) {
+	band_change_removal =
+		fw_has_capa(&mvm->fw->ucode_capa,
+			    IWL_UCODE_TLV_CAPA_BINDING_CDB_SUPPORT) &&
+		mvmvif->phy_ctxt->channel->band != chandef.chan->band;
+
+	if (mvmvif->phy_ctxt->ref == 1 && !band_change_removal) {
+		/*
+		 * Change the PHY context configuration as it is currently
+		 * referenced only by the P2P Device MAC (and we can modify it)
+		 */
 		ret = iwl_mvm_phy_ctxt_changed(mvm, mvmvif->phy_ctxt,
 					       &chandef, 1, 1);
 		if (ret)
 			goto out_unlock;
 	} else {
 		/*
-		 * The PHY context is shared with other MACs. Need to remove the
-		 * P2P Device from the binding, allocate an new PHY context and
-		 * create a new binding
+		 * The PHY context is shared with other MACs (or we're trying to
+		 * switch bands), so remove the P2P Device from the binding,
+		 * allocate an new PHY context and create a new binding.
 		 */
 		phy_ctxt = iwl_mvm_get_free_phy_ctxt(mvm);
 		if (!phy_ctxt) {