uhd: added subtree capability to property tree

9 files changed, 127 insertions, 99 deletions

diff --git a/host/include/uhd/property_tree.hpp b/host/include/uhd/property_tree.hpp
index c41a129b1..cd8cba7e5 100644
--- a/host/include/uhd/property_tree.hpp
+++ b/host/include/uhd/property_tree.hpp
@@ -109,14 +109,17 @@ public:
     //! Create a new + empty property tree
     static sptr make(void);
 
+    //! Get a subtree with a new root starting at path
+    virtual sptr subtree(const path_type &path) const = 0;
+
     //! Remove a property or directory (recursive)
     virtual void remove(const path_type &path) = 0;
 
     //! True if the path exists in the tree
-    virtual bool exists(const path_type &path) = 0;
+    virtual bool exists(const path_type &path) const = 0;
 
     //! Get an iterable to all things in the given path
-    virtual std::vector<std::string> list(const path_type &path) = 0;
+    virtual std::vector<std::string> list(const path_type &path) const = 0;
 
     //! Create a new property entry in the tree
     template <typename T> property<T> &create(const path_type &path);
@@ -129,7 +132,7 @@ private:
     virtual void _create(const path_type &path, const boost::shared_ptr<void> &prop) = 0;
 
     //! Internal access property with wild-card type
-    virtual boost::shared_ptr<void> &_access(const path_type &path) = 0;
+    virtual boost::shared_ptr<void> &_access(const path_type &path) const = 0;
 
 };
 
diff --git a/host/include/uhd/usrp/dboard_manager.hpp b/host/include/uhd/usrp/dboard_manager.hpp
index 84808ea72..091769a5c 100644
--- a/host/include/uhd/usrp/dboard_manager.hpp
+++ b/host/include/uhd/usrp/dboard_manager.hpp
@@ -39,9 +39,7 @@ public:
 
     //! It does what it says...
     static void populate_prop_tree_from_subdev(
-        property_tree::sptr tree,
-        const property_tree::path_type &root,
-        wax::obj subdev
+        property_tree::sptr subtree, wax::obj subdev
     );
 
     //dboard constructor (each dboard should have a ::make with this signature)
diff --git a/host/lib/property_tree.cpp b/host/lib/property_tree.cpp
index 4a0b1b061..469d59e0d 100644
--- a/host/lib/property_tree.cpp
+++ b/host/lib/property_tree.cpp
@@ -19,81 +19,112 @@
 #include <uhd/types/dict.hpp>
 #include <boost/foreach.hpp>
 #include <boost/thread/mutex.hpp>
+#include <boost/make_shared.hpp>
 #include <iostream>
 
 class property_tree_impl : public uhd::property_tree{
 public:
 
-    void remove(const path_type &path){
-        boost::mutex::scoped_lock lock(_mutex);
+    property_tree_impl(const path_type &root = path_type()):
+        _root(root)
+    {
+        _guts = boost::make_shared<tree_guts_type>();
+    }
+
+    sptr subtree(const path_type &path_) const{
+        const path_type path = _root / path_;
+        boost::mutex::scoped_lock lock(_guts->mutex);
+
+        property_tree_impl *subtree = new property_tree_impl(path);
+        subtree->_guts = this->_guts; //copy the guts sptr
+        return sptr(subtree);
+    }
+
+    void remove(const path_type &path_){
+        const path_type path = _root / path_;
+        boost::mutex::scoped_lock lock(_guts->mutex);
 
         node_type *parent = NULL;
-        node_type *node = &_root;
-        BOOST_FOREACH(const std::string &leaf, path){
-            if (not node->has_key(leaf)) throw_path_not_found(path);
+        node_type *node = &_guts->root;
+        BOOST_FOREACH(const std::string &branch, path){
+            if (not node->has_key(branch)) throw_path_not_found(path);
             parent = node;
-            node = &(*node)[leaf];
+            node = &(*node)[branch];
         }
         if (parent == NULL) throw uhd::runtime_error("Cannot uproot");
         parent->pop(path.leaf());
     }
 
-    bool exists(const path_type &path){
-        boost::mutex::scoped_lock lock(_mutex);
+    bool exists(const path_type &path_) const{
+        const path_type path = _root / path_;
+        boost::mutex::scoped_lock lock(_guts->mutex);
 
-        node_type *node = &_root;
-        BOOST_FOREACH(const std::string &leaf, path){
-            if (not node->has_key(leaf)) return false;
-            node = &(*node)[leaf];
+        node_type *node = &_guts->root;
+        BOOST_FOREACH(const std::string &branch, path){
+            if (not node->has_key(branch)) return false;
+            node = &(*node)[branch];
         }
         return true;
     }
 
-    std::vector<std::string> list(const path_type &path){
-        boost::mutex::scoped_lock lock(_mutex);
+    std::vector<std::string> list(const path_type &path_) const{
+        const path_type path = _root / path_;
+        boost::mutex::scoped_lock lock(_guts->mutex);
 
-        node_type *node = &_root;
-        BOOST_FOREACH(const std::string &leaf, path){
-            if (not node->has_key(leaf)) throw_path_not_found(path);
-            node = &(*node)[leaf];
+        node_type *node = &_guts->root;
+        BOOST_FOREACH(const std::string &branch, path){
+            if (not node->has_key(branch)) throw_path_not_found(path);
+            node = &(*node)[branch];
         }
 
         return node->keys();
     }
 
-    void _create(const path_type &path, const boost::shared_ptr<void> &prop){
-        boost::mutex::scoped_lock lock(_mutex);
+    void _create(const path_type &path_, const boost::shared_ptr<void> &prop){
+        const path_type path = _root / path_;
+        boost::mutex::scoped_lock lock(_guts->mutex);
 
-        node_type *node = &_root;
-        BOOST_FOREACH(const std::string &leaf, path){
-            if (not node->has_key(leaf)) (*node)[leaf] = node_type();
-            node = &(*node)[leaf];
+        node_type *node = &_guts->root;
+        BOOST_FOREACH(const std::string &branch, path){
+            if (not node->has_key(branch)) (*node)[branch] = node_type();
+            node = &(*node)[branch];
         }
+        if (node->prop.get() != NULL) throw uhd::runtime_error("Cannot create! Property already exists at: " + path.string());
         node->prop = prop;
     }
 
-    boost::shared_ptr<void> &_access(const path_type &path){
-        boost::mutex::scoped_lock lock(_mutex);
+    boost::shared_ptr<void> &_access(const path_type &path_) const{
+        const path_type path = _root / path_;
+        boost::mutex::scoped_lock lock(_guts->mutex);
 
-        node_type *node = &_root;
-        BOOST_FOREACH(const std::string &leaf, path){
-            if (not node->has_key(leaf)) throw_path_not_found(path);
-            node = &(*node)[leaf];
+        node_type *node = &_guts->root;
+        BOOST_FOREACH(const std::string &branch, path){
+            if (not node->has_key(branch)) throw_path_not_found(path);
+            node = &(*node)[branch];
         }
-        if (node->prop.get() == NULL) throw uhd::type_error("Uninitialized property at: " + path.string());
+        if (node->prop.get() == NULL) throw uhd::runtime_error("Cannot access! Property uninitialized at: " + path.string());
         return node->prop;
     }
 
 private:
-    void throw_path_not_found(const path_type &path){
+    void throw_path_not_found(const path_type &path) const{
         throw uhd::lookup_error("Path not found in tree: " + path.string());
     }
 
+    //basic structural node element
     struct node_type : uhd::dict<std::string, node_type>{
         boost::shared_ptr<void> prop;
-    } _root;
+    };
+
+    //tree guts which may be referenced in a subtree
+    struct tree_guts_type{
+        node_type root;
+        boost::mutex mutex;
+    };
 
-    boost::mutex _mutex;
+    //members, the tree and root prefix
+    boost::shared_ptr<tree_guts_type> _guts;
+    const path_type _root;
 };
 
 uhd::property_tree::sptr uhd::property_tree::make(void){
diff --git a/host/lib/usrp/b100/b100_impl.cpp b/host/lib/usrp/b100/b100_impl.cpp
index b58e70694..2e2421ed3 100644
--- a/host/lib/usrp/b100/b100_impl.cpp
+++ b/host/lib/usrp/b100/b100_impl.cpp
@@ -366,13 +366,13 @@ b100_impl::b100_impl(const device_addr_t &device_addr){
     );
     BOOST_FOREACH(const std::string &name, _dboard_manager->get_rx_subdev_names()){
         dboard_manager::populate_prop_tree_from_subdev(
-            _tree, mb_path / "dboards/A/rx_frontends" / name,
+            _tree->subtree(mb_path / "dboards/A/rx_frontends" / name),
             _dboard_manager->get_rx_subdev(name)
         );
     }
     BOOST_FOREACH(const std::string &name, _dboard_manager->get_tx_subdev_names()){
         dboard_manager::populate_prop_tree_from_subdev(
-            _tree, mb_path / "dboards/A/tx_frontends" / name,
+            _tree->subtree(mb_path / "dboards/A/tx_frontends" / name),
             _dboard_manager->get_tx_subdev(name)
         );
     }
diff --git a/host/lib/usrp/dboard_manager.cpp b/host/lib/usrp/dboard_manager.cpp
index fae3d35b3..3f4b5a511 100644
--- a/host/lib/usrp/dboard_manager.cpp
+++ b/host/lib/usrp/dboard_manager.cpp
@@ -478,52 +478,50 @@ static double get_bw(wax::obj subdev){
 }
 
 void dboard_manager::populate_prop_tree_from_subdev(
-    property_tree::sptr tree,
-    const property_tree::path_type &root,
-    wax::obj subdev
+    property_tree::sptr subtree, wax::obj subdev
 ){
-    tree->create<std::string>(root / "name").set(subdev[SUBDEV_PROP_NAME].as<std::string>());
+    subtree->create<std::string>("name").set(subdev[SUBDEV_PROP_NAME].as<std::string>());
 
     const prop_names_t sensor_names = subdev[SUBDEV_PROP_SENSOR_NAMES].as<prop_names_t>();
     BOOST_FOREACH(const std::string &name, sensor_names){
-        tree->create<sensor_value_t>(root / "sensors" / name)
+        subtree->create<sensor_value_t>("sensors/" + name)
             .publish(boost::bind(&get_sensor, subdev, name));
     }
 
     const prop_names_t gain_names = subdev[SUBDEV_PROP_GAIN_NAMES].as<prop_names_t>();
-    tree->create<int>(root / "gains"); //phony property so this dir exists
+    subtree->create<int>("gains"); //phony property so this dir exists
     BOOST_FOREACH(const std::string &name, gain_names){
-        tree->create<double>(root / "gains" / name / "value")
+        subtree->create<double>("gains/" + name + "/value")
             .publish(boost::bind(&get_gain, subdev, name))
             .subscribe(boost::bind(&set_gain, subdev, name, _1));
-        tree->create<meta_range_t>(root / "gains" / name / "range")
+        subtree->create<meta_range_t>("gains/" + name + "/range")
             .publish(boost::bind(&get_gain_range, subdev, name));
     }
 
-    tree->create<double>(root / "freq/value")
+    subtree->create<double>("freq/value")
         .publish(boost::bind(&get_freq, subdev))
         .subscribe(boost::bind(&set_freq, subdev, _1));
 
-    tree->create<meta_range_t>(root / "freq/range")
+    subtree->create<meta_range_t>("freq/range")
         .publish(boost::bind(&get_freq_range, subdev));
 
-    tree->create<std::string>(root / "antenna/value")
+    subtree->create<std::string>("antenna/value")
         .publish(boost::bind(&get_ant, subdev))
         .subscribe(boost::bind(&set_ant, subdev, _1));
 
-    tree->create<std::vector<std::string> >(root / "antenna/options")
+    subtree->create<std::vector<std::string> >("antenna/options")
         .publish(boost::bind(&get_ants, subdev));
 
-    tree->create<std::string>(root / "connection")
+    subtree->create<std::string>("connection")
         .publish(boost::bind(&get_conn, subdev));
 
-    tree->create<bool>(root / "enabled")
+    subtree->create<bool>("enabled")
         .coerce(boost::bind(&get_set_enb, subdev, _1));
 
-    tree->create<bool>(root / "use_lo_offset")
+    subtree->create<bool>("use_lo_offset")
         .publish(boost::bind(&get_use_lo_off, subdev));
 
-    tree->create<double>(root / "bandwidth/value")
+    subtree->create<double>("bandwidth/value")
         .publish(boost::bind(&get_bw, subdev))
         .subscribe(boost::bind(&set_bw, subdev, _1));
 }
diff --git a/host/lib/usrp/e100/e100_impl.cpp b/host/lib/usrp/e100/e100_impl.cpp
index a86a75816..cca4ee9b3 100644
--- a/host/lib/usrp/e100/e100_impl.cpp
+++ b/host/lib/usrp/e100/e100_impl.cpp
@@ -325,13 +325,13 @@ e100_impl::e100_impl(const uhd::device_addr_t &device_addr){
     );
     BOOST_FOREACH(const std::string &name, _dboard_manager->get_rx_subdev_names()){
         dboard_manager::populate_prop_tree_from_subdev(
-            _tree, mb_path / "dboards/A/rx_frontends" / name,
+            _tree->subtree(mb_path / "dboards/A/rx_frontends" / name),
             _dboard_manager->get_rx_subdev(name)
         );
     }
     BOOST_FOREACH(const std::string &name, _dboard_manager->get_tx_subdev_names()){
         dboard_manager::populate_prop_tree_from_subdev(
-            _tree, mb_path / "dboards/A/tx_frontends" / name,
+            _tree->subtree(mb_path / "dboards/A/tx_frontends" / name),
             _dboard_manager->get_tx_subdev(name)
         );
     }
diff --git a/host/lib/usrp/multi_usrp.cpp b/host/lib/usrp/multi_usrp.cpp
index 2f416d93a..f9f5e675f 100644
--- a/host/lib/usrp/multi_usrp.cpp
+++ b/host/lib/usrp/multi_usrp.cpp
@@ -68,23 +68,23 @@ static void do_tune_freq_warning_message(
 /***********************************************************************
  * Gain helper functions
  **********************************************************************/
-static double get_gain_value(property_tree::sptr tree, const property_tree::path_type &path){
-    return tree->access<double>(path / "value").get();
+static double get_gain_value(property_tree::sptr subtree){
+    return subtree->access<double>("value").get();
 }
 
-static void set_gain_value(property_tree::sptr tree, const property_tree::path_type &path, const double gain){
-    tree->access<double>(path / "value").set(gain);
+static void set_gain_value(property_tree::sptr subtree, const double gain){
+    subtree->access<double>("value").set(gain);
 }
 
-static meta_range_t get_gain_range(property_tree::sptr tree, const property_tree::path_type &path){
-    return tree->access<meta_range_t>(path / "range").get();
+static meta_range_t get_gain_range(property_tree::sptr subtree){
+    return subtree->access<meta_range_t>("range").get();
 }
 
-static gain_fcns_t make_gain_fcns_from_path(property_tree::sptr tree, const property_tree::path_type &path){
+static gain_fcns_t make_gain_fcns_from_subtree(property_tree::sptr subtree){
     gain_fcns_t gain_fcns;
-    gain_fcns.get_range = boost::bind(&get_gain_range, tree, path);
-    gain_fcns.get_value = boost::bind(&get_gain_value, tree, path);
-    gain_fcns.set_value = boost::bind(&set_gain_value, tree, path, _1);
+    gain_fcns.get_range = boost::bind(&get_gain_range, subtree);
+    gain_fcns.get_value = boost::bind(&get_gain_value, subtree);
+    gain_fcns.set_value = boost::bind(&set_gain_value, subtree, _1);
     return gain_fcns;
 }
 
@@ -96,20 +96,19 @@ static const double TX_SIGN = -1.0;
 
 static tune_result_t tune_xx_subdev_and_dsp(
     const double xx_sign,
-    property_tree::sptr tree,
-    const property_tree::path_type &dsp_path,
-    const property_tree::path_type &rf_fe_path,
+    property_tree::sptr dsp_subtree,
+    property_tree::sptr rf_fe_subtree,
     const tune_request_t &tune_request
 ){
     //------------------------------------------------------------------
     //-- calculate the LO offset, only used with automatic policy
     //------------------------------------------------------------------
     double lo_offset = 0.0;
-    if (tree->access<bool>(rf_fe_path / "use_lo_offset").get()){
+    if (rf_fe_subtree->access<bool>("use_lo_offset").get()){
         //If the local oscillator will be in the passband, use an offset.
         //But constrain the LO offset by the width of the filter bandwidth.
-        const double rate = tree->access<double>(dsp_path / "rate" / "value").get();
-        const double bw = tree->access<double>(rf_fe_path / "bandwidth" / "value").get();
+        const double rate = dsp_subtree->access<double>("rate/value").get();
+        const double bw = rf_fe_subtree->access<double>("bandwidth/value").get();
         if (bw > rate) lo_offset = std::min((bw - rate)/2, rate/2);
     }
 
@@ -120,17 +119,17 @@ static tune_result_t tune_xx_subdev_and_dsp(
     switch (tune_request.rf_freq_policy){
     case tune_request_t::POLICY_AUTO:
         target_rf_freq = tune_request.target_freq + lo_offset;
-        tree->access<double>(rf_fe_path / "freq" / "value").set(target_rf_freq);
+        rf_fe_subtree->access<double>("freq/value").set(target_rf_freq);
         break;
 
     case tune_request_t::POLICY_MANUAL:
         target_rf_freq = tune_request.rf_freq;
-        tree->access<double>(rf_fe_path / "freq" / "value").set(target_rf_freq);
+        rf_fe_subtree->access<double>("freq/value").set(target_rf_freq);
         break;
 
     case tune_request_t::POLICY_NONE: break; //does not set
     }
-    const double actual_rf_freq = tree->access<double>(rf_fe_path / "freq" / "value").get();
+    const double actual_rf_freq = rf_fe_subtree->access<double>("freq/value").get();
 
     //------------------------------------------------------------------
     //-- calculate the dsp freq, only used with automatic policy
@@ -145,17 +144,17 @@ static tune_result_t tune_xx_subdev_and_dsp(
     //------------------------------------------------------------------
     switch (tune_request.dsp_freq_policy){
     case tune_request_t::POLICY_AUTO:
-        tree->access<double>(dsp_path / "freq" / "value").set(target_dsp_freq);
+        dsp_subtree->access<double>("freq/value").set(target_dsp_freq);
         break;
 
     case tune_request_t::POLICY_MANUAL:
         target_dsp_freq = tune_request.dsp_freq;
-        tree->access<double>(dsp_path / "freq" / "value").set(target_dsp_freq);
+        dsp_subtree->access<double>("freq/value").set(target_dsp_freq);
         break;
 
     case tune_request_t::POLICY_NONE: break; //does not set
     }
-    const double actual_dsp_freq = tree->access<double>(dsp_path / "freq" / "value").get();
+    const double actual_dsp_freq = dsp_subtree->access<double>("freq/value").get();
 
     //------------------------------------------------------------------
     //-- load and return the tune result
@@ -170,13 +169,12 @@ static tune_result_t tune_xx_subdev_and_dsp(
 
 static double derive_freq_from_xx_subdev_and_dsp(
     const double xx_sign,
-    property_tree::sptr tree,
-    const property_tree::path_type &dsp_path,
-    const property_tree::path_type &rf_fe_path
+    property_tree::sptr dsp_subtree,
+    property_tree::sptr rf_fe_subtree
 ){
     //extract actual dsp and IF frequencies
-    const double actual_rf_freq = tree->access<double>(rf_fe_path / "freq" / "value").get();
-    const double actual_dsp_freq = tree->access<double>(dsp_path / "freq" / "value").get();
+    const double actual_rf_freq = rf_fe_subtree->access<double>("freq/value").get();
+    const double actual_dsp_freq = dsp_subtree->access<double>("freq/value").get();
 
     //invert the sign on the dsp freq for transmit
     return actual_rf_freq - actual_dsp_freq * xx_sign;
@@ -434,13 +432,13 @@ public:
     }
 
     tune_result_t set_rx_freq(const tune_request_t &tune_request, size_t chan){
-        tune_result_t r = tune_xx_subdev_and_dsp(RX_SIGN, _tree, rx_dsp_root(chan), rx_rf_fe_root(chan), tune_request);
+        tune_result_t r = tune_xx_subdev_and_dsp(RX_SIGN, _tree->subtree(rx_dsp_root(chan)), _tree->subtree(rx_rf_fe_root(chan)), tune_request);
         do_tune_freq_warning_message(tune_request.target_freq, get_rx_freq(chan), "RX");
         return r;
     }
 
     double get_rx_freq(size_t chan){
-        return derive_freq_from_xx_subdev_and_dsp(RX_SIGN, _tree, rx_dsp_root(chan), rx_rf_fe_root(chan));
+        return derive_freq_from_xx_subdev_and_dsp(RX_SIGN, _tree->subtree(rx_dsp_root(chan)), _tree->subtree(rx_rf_fe_root(chan)));
     }
 
     freq_range_t get_rx_freq_range(size_t chan){
@@ -542,13 +540,13 @@ public:
     }
 
     tune_result_t set_tx_freq(const tune_request_t &tune_request, size_t chan){
-        tune_result_t r = tune_xx_subdev_and_dsp(TX_SIGN, _tree, tx_dsp_root(chan), tx_rf_fe_root(chan), tune_request);
+        tune_result_t r = tune_xx_subdev_and_dsp(TX_SIGN, _tree->subtree(tx_dsp_root(chan)), _tree->subtree(tx_rf_fe_root(chan)), tune_request);
         do_tune_freq_warning_message(tune_request.target_freq, get_tx_freq(chan), "TX");
         return r;
     }
 
     double get_tx_freq(size_t chan){
-        return derive_freq_from_xx_subdev_and_dsp(TX_SIGN, _tree, tx_dsp_root(chan), tx_rf_fe_root(chan));
+        return derive_freq_from_xx_subdev_and_dsp(TX_SIGN, _tree->subtree(tx_dsp_root(chan)), _tree->subtree(tx_rf_fe_root(chan)));
     }
 
     freq_range_t get_tx_freq_range(size_t chan){
@@ -670,10 +668,10 @@ private:
         const subdev_spec_pair_t spec = get_rx_subdev_spec(mcp.mboard).at(mcp.chan);
         gain_group::sptr gg = gain_group::make();
         BOOST_FOREACH(const std::string &name, _tree->list(mb_root(mcp.mboard) / "rx_codecs" / spec.db_name / "gains")){
-            gg->register_fcns("ADC-"+name, make_gain_fcns_from_path(_tree, mb_root(mcp.mboard) / "rx_codecs" / spec.db_name / "gains" / name), 0 /* low prio */);
+            gg->register_fcns("ADC-"+name, make_gain_fcns_from_subtree(_tree->subtree(mb_root(mcp.mboard) / "rx_codecs" / spec.db_name / "gains" / name)), 0 /* low prio */);
         }
         BOOST_FOREACH(const std::string &name, _tree->list(rx_rf_fe_root(chan) / "gains")){
-            gg->register_fcns(name, make_gain_fcns_from_path(_tree, rx_rf_fe_root(chan) / "gains" / name), 1 /* high prio */);
+            gg->register_fcns(name, make_gain_fcns_from_subtree(_tree->subtree(rx_rf_fe_root(chan) / "gains" / name)), 1 /* high prio */);
         }
         return gg;
     }
@@ -683,10 +681,10 @@ private:
         const subdev_spec_pair_t spec = get_tx_subdev_spec(mcp.mboard).at(mcp.chan);
         gain_group::sptr gg = gain_group::make();
         BOOST_FOREACH(const std::string &name, _tree->list(mb_root(mcp.mboard) / "tx_codecs" / spec.db_name / "gains")){
-            gg->register_fcns("ADC-"+name, make_gain_fcns_from_path(_tree, mb_root(mcp.mboard) / "tx_codecs" / spec.db_name / "gains" / name), 1 /* high prio */);
+            gg->register_fcns("ADC-"+name, make_gain_fcns_from_subtree(_tree->subtree(mb_root(mcp.mboard) / "tx_codecs" / spec.db_name / "gains" / name)), 1 /* high prio */);
         }
         BOOST_FOREACH(const std::string &name, _tree->list(tx_rf_fe_root(chan) / "gains")){
-            gg->register_fcns(name, make_gain_fcns_from_path(_tree, tx_rf_fe_root(chan) / "gains" / name), 0 /* low prio */);
+            gg->register_fcns(name, make_gain_fcns_from_subtree(_tree->subtree(tx_rf_fe_root(chan) / "gains" / name)), 0 /* low prio */);
         }
         return gg;
     }
diff --git a/host/lib/usrp/usrp1/usrp1_impl.cpp b/host/lib/usrp/usrp1/usrp1_impl.cpp
index 78137178b..f27fc0768 100644
--- a/host/lib/usrp/usrp1/usrp1_impl.cpp
+++ b/host/lib/usrp/usrp1/usrp1_impl.cpp
@@ -346,13 +346,13 @@ usrp1_impl::usrp1_impl(const device_addr_t &device_addr){
         );
         BOOST_FOREACH(const std::string &name, _dbc[db].dboard_manager->get_rx_subdev_names()){
             dboard_manager::populate_prop_tree_from_subdev(
-                _tree, mb_path / "dboards" / db/ "rx_frontends" / name,
+                _tree->subtree(mb_path / "dboards" / db/ "rx_frontends" / name),
                 _dbc[db].dboard_manager->get_rx_subdev(name)
             );
         }
         BOOST_FOREACH(const std::string &name, _dbc[db].dboard_manager->get_tx_subdev_names()){
             dboard_manager::populate_prop_tree_from_subdev(
-                _tree, mb_path / "dboards" / db/ "tx_frontends" / name,
+                _tree->subtree(mb_path / "dboards" / db/ "tx_frontends" / name),
                 _dbc[db].dboard_manager->get_tx_subdev(name)
             );
         }
diff --git a/host/lib/usrp/usrp2/usrp2_impl.cpp b/host/lib/usrp/usrp2/usrp2_impl.cpp
index 390d1813b..a42d1aae0 100644
--- a/host/lib/usrp/usrp2/usrp2_impl.cpp
+++ b/host/lib/usrp/usrp2/usrp2_impl.cpp
@@ -551,13 +551,13 @@ usrp2_impl::usrp2_impl(const device_addr_t &_device_addr){
         );
         BOOST_FOREACH(const std::string &name, _mbc[mb].dboard_manager->get_rx_subdev_names()){
             dboard_manager::populate_prop_tree_from_subdev(
-                _tree, mb_path / "dboards/A/rx_frontends" / name,
+                _tree->subtree(mb_path / "dboards/A/rx_frontends" / name),
                 _mbc[mb].dboard_manager->get_rx_subdev(name)
             );
         }
         BOOST_FOREACH(const std::string &name, _mbc[mb].dboard_manager->get_tx_subdev_names()){
             dboard_manager::populate_prop_tree_from_subdev(
-                _tree, mb_path / "dboards/A/tx_frontends" / name,
+                _tree->subtree(mb_path / "dboards/A/tx_frontends" / name),
                 _mbc[mb].dboard_manager->get_tx_subdev(name)
             );
         }