usrp1: Cleanup libusb device handling

This patch limits all libusb device enumeration operations to FSF
(Vendor ID = 0xfffe) devices, which removes a lot of unncessary
libusb output when debug mode is enabled. The reference counts
held by the libusb device list are also reduced, which prevents
holding references to unused devices.

3 files changed, 50 insertions, 33 deletions

diff --git a/host/lib/transport/libusb1_base.cpp b/host/lib/transport/libusb1_base.cpp
index 6965de214..493d4eff3 100644
--- a/host/lib/transport/libusb1_base.cpp
+++ b/host/lib/transport/libusb1_base.cpp
@@ -16,10 +16,22 @@
 //
 
 #include "libusb1_base.hpp"
+#include <uhd/utils/assert.hpp>
 #include <iostream>
 
 using namespace uhd::transport;
 
+bool check_fsf_device(libusb_device *dev)
+{
+    libusb_device_descriptor desc;
+
+    if (libusb_get_device_descriptor(dev, &desc) < 0) {
+        UHD_ASSERT_THROW("USB: failed to get device descriptor");
+    }
+
+    return desc.idVendor == 0xfffe;
+}
+
 void libusb::init(libusb_context **ctx, int debug_level)
 {
     if (libusb_init(ctx) < 0)
@@ -28,27 +40,47 @@ void libusb::init(libusb_context **ctx, int debug_level)
     libusb_set_debug(*ctx, debug_level);
 }
 
+std::vector<libusb_device *> libusb::get_fsf_device_list(libusb_context *ctx)
+{
+    libusb_device **libusb_dev_list;
+    std::vector<libusb_device *> fsf_dev_list;
+
+    ssize_t dev_cnt = libusb_get_device_list(ctx, &libusb_dev_list);
+
+    //find the FSF devices 
+    for (ssize_t i = 0; i < dev_cnt; i++) {
+        libusb_device *dev = libusb_dev_list[i];
+
+        if (check_fsf_device(dev))
+            fsf_dev_list.push_back(dev);
+        else
+            libusb_unref_device(dev);
+    }
+
+    libusb_free_device_list(libusb_dev_list, 0);
+
+    return fsf_dev_list;
+}
 
 libusb_device_handle *libusb::open_device(libusb_context *ctx,
                                           usb_device_handle::sptr handle)
 {
-    libusb_device **dev_list;
-    libusb_device_handle *dev_handle;
+    libusb_device_handle *dev_handle = NULL;
+    std::vector<libusb_device *> fsf_dev_list = get_fsf_device_list(ctx);
 
-    ssize_t dev_cnt = libusb_get_device_list(ctx, &dev_list);
-
-    //find and open the receive device
-    for (ssize_t i = 0; i < dev_cnt; i++) {
-        libusb_device *dev = dev_list[i];
+    //find and open the USB device 
+    for (size_t i = 0; i < fsf_dev_list.size(); i++) {
+        libusb_device *dev = fsf_dev_list[i];
 
         if (compare_device(dev, handle)) {
             libusb_open(dev, &dev_handle);
+            libusb_unref_device(dev);
             break;
         }
+            
+        libusb_unref_device(dev);
     }
 
-    libusb_free_device_list(dev_list, 0);
-
     return dev_handle;
 }
 
diff --git a/host/lib/transport/libusb1_base.hpp b/host/lib/transport/libusb1_base.hpp
index ae560cd52..708a42c73 100644
--- a/host/lib/transport/libusb1_base.hpp
+++ b/host/lib/transport/libusb1_base.hpp
@@ -27,6 +27,8 @@ namespace uhd { namespace transport {
 namespace libusb {
     void init(libusb_context **ctx, int debug_level);
 
+    std::vector<libusb_device *> get_fsf_device_list(libusb_context *ctx);
+
     libusb_device_handle *open_device(libusb_context *ctx,
                                       usb_device_handle::sptr handle);
 
diff --git a/host/lib/transport/libusb1_device_handle.cpp b/host/lib/transport/libusb1_device_handle.cpp
index 5289f668f..4885099eb 100644
--- a/host/lib/transport/libusb1_device_handle.cpp
+++ b/host/lib/transport/libusb1_device_handle.cpp
@@ -88,38 +88,21 @@ usb_device_handle::sptr make_usb_device_handle(libusb_device *dev)
         device_addr));
 }
 
-bool check_fsf_device(libusb_device *dev)
-{
-    libusb_device_descriptor desc;
-
-    if (libusb_get_device_descriptor(dev, &desc) < 0) {
-        UHD_ASSERT_THROW("USB: failed to get device descriptor");
-    }
-
-    return desc.idVendor == 0xfffe;
-}
-
 std::vector<usb_device_handle::sptr> usb_device_handle::get_device_list()
 {
     libusb_context *ctx = NULL;
-    libusb_device **list;
-    std::vector<usb_device_handle::sptr> device_list;
+    std::vector<libusb_device *> libusb_device_list;
+    std::vector<usb_device_handle::sptr> device_handle_list;
 
     libusb::init(&ctx, libusb_debug_level);
 
-    ssize_t cnt = libusb_get_device_list(ctx, &list);
-
-    if (cnt < 0)
-        throw std::runtime_error("USB: enumeration failed");
+    libusb_device_list = libusb::get_fsf_device_list(ctx);
 
-    ssize_t i = 0;
-    for (i = 0; i < cnt; i++) {
-        libusb_device *dev = list[i];
-        if (check_fsf_device(dev)) 
-            device_list.push_back(make_usb_device_handle(dev));
+    for (size_t i = 0; i < libusb_device_list.size(); i++) {
+        libusb_device *dev = libusb_device_list[i];
+        device_handle_list.push_back(make_usb_device_handle(dev));
     }
 
-    libusb_free_device_list(list, 0);
     libusb_exit(ctx);
-    return device_list; 
+    return device_handle_list; 
 }