P2P: Prefer operating channels where HT40 is possible

When no other user preference is specified, opt to use an operating
channel that allows HT40 operation. This way, if driver capabilities
and regulatory constraints allow, we might enjoy increased bandwidth.

Signed-hostap: Arik Nemtsov <arik@wizery.com>

src/p2p/p2p_go_neg.c

@@ -390,6 +390,21 @@ void p2p_reselect_channel(struct p2p_data *p2p,
 		}
 	}
 
+	/* Try a channel where we might be able to use HT40 */
+	for (i = 0; i < intersection->reg_classes; i++) {
+		struct p2p_reg_class *c = &intersection->reg_class[i];
+		if (c->reg_class == 116 || c->reg_class == 117 ||
+		    c->reg_class == 126 || c->reg_class == 127) {
+			wpa_msg(p2p->cfg->msg_ctx, MSG_DEBUG,
+				"P2P: Pick possible HT40 channel (reg_class "
+				"%u channel %u) from intersection",
+				c->reg_class, c->channel[0]);
+			p2p->op_reg_class = c->reg_class;
+			p2p->op_channel = c->channel[0];
+			return;
+		}
+	}
+
 	/*
 	 * Fall back to whatever is included in the channel intersection since
 	 * no better options seems to be available.