libdce[LINUX] : Mutex protection support and other bug fixes

* The dce_init/dce_deinit APIs can be called multiple times by applications.
  This is called from multiple thread contexts in the viddec3test and is also
  invoked several times by the GStreamer framework.
* But certain init functions and deinit operations need to be done only on the
  first and last calls of the respective APIs.
* Additionally, according the pthread documentation we need to use **either**
  the PTHREAD_MUTEX_INITIALIZER or the pthread_mutex_init APIs with the attribs
* The protection for the dce_init with the ref count mechanism is additionally
  needed for the mutex initialization because if this is not done conditionally
  (for the first dce_init) sequence, the subsequent call to this API would
  actually reinit the mutex value and cause the new thread sequence to acquire
  the same.

Change-Id: I2d129a2b030a25c4e8c5f621abf05d68562db6b8
Signed-off-by: Karthik Ramanan <a0393906@ti.com>
Signed-off-by: Buddy Liong <buddy.budiono@ti.com>

2 files changed, 22 insertions, 16 deletions

diff --git a/libdce.c b/libdce.c
index 7704613..108d8f3 100644
--- a/libdce.c
+++ b/libdce.c
@@ -50,7 +50,13 @@
 /* Handle used for Remote Communication              */
 MmRpc_Handle    MmRpcHandle[MAX_REMOTEDEVICES] = { NULL};
 Engine_Handle   gEngineHandle[MAX_INSTANCES][MAX_REMOTEDEVICES] = { {NULL, NULL}};
+
+#ifdef BUILDOS_LINUX
+pthread_mutex_t    ipc_mutex;
+#else
 pthread_mutex_t    ipc_mutex = PTHREAD_MUTEX_INITIALIZER;
+#endif
+
 static int      __ClientCount[MAX_REMOTEDEVICES] = {0};
 int             dce_debug = DCE_DEBUG_LEVEL;
 const String DCE_DEVICE_NAME[MAX_REMOTEDEVICES]= {"rpmsg-dce","rpmsg-dce-dsp"};
diff --git a/libdce_linux.c b/libdce_linux.c
index 3de2e0a..43ea740 100644
--- a/libdce_linux.c
+++ b/libdce_linux.c
@@ -33,7 +33,6 @@
 #include <stdlib.h>
 #include <string.h>
 #include <stdio.h>
-
 #include <pthread.h>
 
 #include <xf86drm.h>
@@ -48,31 +47,33 @@
 
 #define INVALID_DRM_FD (-1)
 
-int                    OmapDrm_FD  = INVALID_DRM_FD;
-int                    bDrmOpenedByDce = FALSE;
+static int             OmapDrm_FD  = INVALID_DRM_FD;
+static int             dce_init_count = 0;
 struct omap_device    *OmapDev     = NULL;
 extern MmRpc_Handle    MmRpcHandle[];
-
 extern pthread_mutex_t    ipc_mutex;
 
 void *dce_init(void)
 {
     dce_error_status    eError = DCE_EOK;
+    pthread_mutexattr_t attr;
 
     DEBUG(" >> dce_init");
 
-    pthread_mutexattr_t attr;
-    pthread_mutexattr_init(&attr);
-    pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
-    pthread_mutex_init(&ipc_mutex, &attr);
+    /* Use this for refcount */
+    dce_init_count++;
 
-    /* Open omapdrm device */
-    if( OmapDrm_FD == INVALID_DRM_FD ) {
-        DEBUG("Open omapdrm device");
+   /* Open omapdrm device only for the first dce_init call */
+    if( dce_init_count == 1 ) {
+        DEBUG("Open omapdrm device and initializing the mutex...");
         OmapDrm_FD = drmOpen("omapdrm", "platform:omapdrm:00");
         _ASSERT(OmapDrm_FD > 0, DCE_EOMAPDRM_FAIL);
-        bDrmOpenedByDce = TRUE;
+
+        pthread_mutexattr_init(&attr);
+        pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
+        pthread_mutex_init(&ipc_mutex, &attr);
     }
+
     OmapDev = omap_device_new(OmapDrm_FD);
     _ASSERT(OmapDev != NULL, DCE_EOMAPDRM_FAIL);
 
@@ -84,12 +85,11 @@ void dce_deinit(void *dev)
 {
     omap_device_del(dev);
     dev = NULL;
-    if (bDrmOpenedByDce == TRUE) {
+    if (--dce_init_count == 0) {
+        DEBUG("Closing omapdrm device...");
         close(OmapDrm_FD);
-        bDrmOpenedByDce = FALSE;
+        OmapDrm_FD = INVALID_DRM_FD;
     }
-    OmapDrm_FD = INVALID_DRM_FD;
-
     return;
 }