Patch to apply to gr-fcdproplus for making it work on kernel 3.8-based systems. Discussion: https://github.com/csete/gqrx/pull/88

hidraw-reopen_v37.patch

diff --git a/lib/fcdproplus_impl.cc b/lib/fcdproplus_impl.cc
index beef6ba..f8f9085 100644
--- a/lib/fcdproplus_impl.cc
+++ b/lib/fcdproplus_impl.cc
@@ -124,8 +124,8 @@ namespace gr {
         /* setup the control part */
         d_control_handle =NULL;
         hid_init();
-        d_control_handle = hid_open ( FCDPROPLUS_VENDOR_ID ,FCDPROPLUS_PRODUCT_ID,NULL );
-        if(d_control_handle == NULL ) {
+        d_path = hid_get_path ( FCDPROPLUS_VENDOR_ID ,FCDPROPLUS_PRODUCT_ID,NULL );
+        if(d_path == NULL ) {
             throw std::runtime_error("FunCube Dongle  V2.0 soundcard found but not controlpart.");
         }
         else {
@@ -138,8 +138,12 @@ namespace gr {
          */
         aucBuf[0] = 0; // Report ID. Ignored by HID Class firmware as only config'd for one report
         aucBuf[1] = FCD_HID_CMD_QUERY;
+        d_control_handle = hid_open_path(d_path);
+        if (!d_control_handle)
+            return;
         hid_write(d_control_handle,aucBuf,65);
         hid_read(d_control_handle,aucBuf,65);
+        hid_close(d_control_handle);
         std::cerr <<"Result of Action :+++++" << std::endl;
         for(int i=2;i<15;i++)
            std::cerr << aucBuf[i];
@@ -152,9 +156,6 @@ namespace gr {
      */
     fcdproplus_impl::~fcdproplus_impl()
     {
-        if(d_control_handle !=0)   {
-            hid_close(d_control_handle);
-        }
         hid_exit();
 
     }
@@ -178,9 +179,13 @@ namespace gr {
         aucBuf[3] = (unsigned char)(nfreq>>8);
         aucBuf[4] = (unsigned char)(nfreq>>16);
         aucBuf[5] = (unsigned char)(nfreq>>24);
+        d_control_handle = hid_open_path(d_path);
+        if (!d_control_handle)
+            return;
         hid_write(d_control_handle, aucBuf, 65);
         aucBuf[1]=0;
         hid_read(d_control_handle, aucBuf, 65);
+        hid_close(d_control_handle);
         if (aucBuf[0]==FCD_HID_CMD_SET_FREQUENCY_HZ && aucBuf[1]==1) {
             nfreq = 0;
             nfreq = (unsigned int) aucBuf[2];
@@ -211,8 +216,12 @@ namespace gr {
         else {
             aucBuf[2]=0;
         }
+		d_control_handle = hid_open_path(d_path);
+        if (!d_control_handle)
+            return;
         hid_write(d_control_handle, aucBuf, 65);
         hid_read(d_control_handle, aucBuf, 65);
+        hid_close(d_control_handle);
         if(aucBuf[0] == FCD_HID_CMD_SET_LNA_GAIN) {
             if (gain != 0) {
                 std::cerr <<" Lna gain enabled" << std::endl;
@@ -238,8 +247,12 @@ namespace gr {
         else {
             aucBuf[2]=0;
         }
+		d_control_handle = hid_open_path(d_path);
+		if (!d_control_handle)
+			return;
         hid_write(d_control_handle, aucBuf, 65);
         hid_read(d_control_handle, aucBuf, 65);
+        hid_close(d_control_handle);
         if(aucBuf[0] == FCD_HID_CMD_SET_MIXER_GAIN) {
             if (gain != 0) {
                 std::cerr <<" Mixer gain enabled" << std::endl;
@@ -278,8 +291,12 @@ namespace gr {
         aucBuf[0] = 0; // Report ID. Ignored by HID Class firmware as only config'd for one report
         aucBuf[1] = FCD_HID_CMD_SET_IF_GAIN;
         aucBuf[2] = (unsigned char) gain;
+        d_control_handle = hid_open_path(d_path);
+        if (!d_control_handle)
+            return;
         hid_write(d_control_handle, aucBuf, 65);
         hid_read(d_control_handle, aucBuf, 65);
+        hid_close(d_control_handle);
         if(aucBuf[0] == FCD_HID_CMD_SET_IF_GAIN) {
             std::cerr <<"If gain set to: "<< gain <<std::endl;
         }
diff --git a/lib/fcdproplus_impl.h b/lib/fcdproplus_impl.h
index 1644ce7..18efa83 100644
--- a/lib/fcdproplus_impl.h
+++ b/lib/fcdproplus_impl.h
@@ -32,6 +32,7 @@ namespace gr {
     {
     private:
       gr::audio::source::sptr fcd;                   /*!< The audio input source */
+      char *d_path;             /*!< handle to control the device, set frequency, etc */
       hid_device *d_control_handle;             /*!< handle to control the device, set frequency, etc */
       unsigned int d_freq_req;                           /*!< The latest requested frequency in Khz */
       unsigned char aucBuf[65];                 /*!< Buffers to read/write control messages to the dongle */
diff --git a/lib/hid/hid.c b/lib/hid/hid.c
index 38f6753..1cfc2a5 100644
--- a/lib/hid/hid.c
+++ b/lib/hid/hid.c
@@ -592,6 +592,35 @@ hid_device * hid_open(unsigned short vendor_id, unsigned short product_id, const
 	return handle;
 }
 
+char* hid_get_path(unsigned short vendor_id, unsigned short product_id, const wchar_t *serial_number)
+{
+	struct hid_device_info *devs, *cur_dev;
+	char *path_to_open = NULL;
+
+	devs = hid_enumerate(vendor_id, product_id);
+	cur_dev = devs;
+	while (cur_dev) {
+		if (cur_dev->vendor_id == vendor_id &&
+		    cur_dev->product_id == product_id) {
+			if (serial_number) {
+				if (wcscmp(serial_number, cur_dev->serial_number) == 0) {
+					path_to_open = strdup(cur_dev->path);
+					break;
+				}
+			}
+			else {
+				path_to_open = strdup(cur_dev->path);
+				break;
+			}
+		}
+		cur_dev = cur_dev->next;
+	}
+
+	hid_free_enumeration(devs);
+
+	return path_to_open;
+}
+
 hid_device * HID_API_EXPORT hid_open_path(const char *path)
 {
 	hid_device *dev = NULL;
diff --git a/lib/hid/hidapi.h b/lib/hid/hidapi.h
index e58e8a4..cf4df7d 100644
--- a/lib/hid/hidapi.h
+++ b/lib/hid/hidapi.h
@@ -157,6 +157,7 @@ extern "C" {
 				This function returns a pointer to a #hid_device object on
 				success or NULL on failure.
 		*/
+		HID_API_EXPORT char * HID_API_CALL hid_get_path(unsigned short vendor_id, unsigned short product_id, const wchar_t *serial_number);
 		HID_API_EXPORT hid_device * HID_API_CALL hid_open(unsigned short vendor_id, unsigned short product_id, const wchar_t *serial_number);
 
 		/** @brief Open a HID device by its path name.