hwcomposer : Use sysfs to read vysnc information

* Read sysfs entries to get vsync timestamp from kernel.
* External display continues to use uevents for hotplug events
* A new thread, vsyncThread is created to read and send vsync
  timestamps to HAL.
* Disable H/W VSYNC for MDP 5.x targets until kernel changes are
  complete.
* Synchronization is needed to make sure read() is not called
by hwcVsyncThread when VSYNC is disabled.

Change-Id: Iab0a94a3cfce9142b8867859f2a7d9bcaecb0996
Acked-by:  Neti Ravi Kumar <ravineti@codeaurora.org>
diff --git a/libhwcomposer/hwc_uevents.cpp b/libhwcomposer/hwc_uevents.cpp
index 3df0e25..ef43f62 100644
--- a/libhwcomposer/hwc_uevents.cpp
+++ b/libhwcomposer/hwc_uevents.cpp
@@ -21,6 +21,7 @@
 #include <hardware_legacy/uevent.h>
 #include <utils/Log.h>
 #include <sys/resource.h>
+#include <sys/prctl.h>
 #include <string.h>
 #include <stdlib.h>
 #include "hwc_utils.h"
@@ -28,8 +29,6 @@
 
 namespace qhwc {
 
-const char* MSMFB_DEVICE_FB0 = "change@/devices/virtual/graphics/fb0";
-const char* MSMFB_DEVICE_FB1 = "change@/devices/virtual/graphics/fb1";
 const char* MSMFB_HDMI_NODE = "fb1";
 
 static void handle_uevent(hwc_context_t* ctx, const char* udata, int len)
@@ -38,65 +37,38 @@
     char* hdmi;
     int64_t timestamp = 0;
     const char *str = udata;
-    int display = HWC_DISPLAY_PRIMARY;
 
     if(!strcasestr(str, "@/devices/virtual/graphics/fb")) {
         ALOGD_IF(UEVENT_DEBUG, "%s: Not Ext Disp Event ", __FUNCTION__);
         return;
     }
-
-    //Check if its primary vsync
-    vsync = !strncmp(str, MSMFB_DEVICE_FB0, strlen(MSMFB_DEVICE_FB0));
-    //If not primary vsync, see if its an external vsync
-    if(isExternalActive(ctx) && !vsync) {
-        vsync = !strncmp(str, MSMFB_DEVICE_FB1, strlen(MSMFB_DEVICE_FB1));
-        display = HWC_DISPLAY_EXTERNAL;
-    }
-
     hdmi = strcasestr(str, MSMFB_HDMI_NODE);
-
-    if(vsync) {
-        str += strlen(str) + 1;
-        while(*str) {
-            if (!strncmp(str, "VSYNC=", strlen("VSYNC="))) {
-                timestamp = strtoull(str + strlen("VSYNC="), NULL, 0);
-                //XXX: Handle vsync from multiple displays
-                ctx->proc->vsync(ctx->proc, display, timestamp);
-            }
-            str += strlen(str) + 1;
-            if(str - udata >= len)
-                break;
-        }
-        return;
-    }
-
-    if(hdmi) {
-        // parse HDMI events
-        // The event will be of the form:
-        // change@/devices/virtual/graphics/fb1 ACTION=change
-        // DEVPATH=/devices/virtual/graphics/fb1
-        // SUBSYSTEM=graphics HDCP_STATE=FAIL MAJOR=29
-        // for now just parsing onlin/offline info is enough
+    // parse HDMI events
+    // The event will be of the form:
+    // change@/devices/virtual/graphics/fb1 ACTION=change
+    // DEVPATH=/devices/virtual/graphics/fb1
+    // SUBSYSTEM=graphics HDCP_STATE=FAIL MAJOR=29
+    // for now just parsing onlin/offline info is enough
+    if (hdmi) {
         str = udata;
         int connected = 0;
         if(!(strncmp(str,"online@",strlen("online@")))) {
             connected = 1;
-            ctx->mExtDisplay->setExternalDisplay(connected);
+            ctx->mExtDisplay->setExternalDisplay(connected);;
         } else if(!(strncmp(str,"offline@",strlen("offline@")))) {
             connected = 0;
-            ctx->mExtDisplay->setExternalDisplay(connected);
+            ctx->mExtDisplay->setExternalDisplay(connected);;
         }
     }
-
 }
 
 static void *uevent_loop(void *param)
 {
     int len = 0;
-    static char udata[4096];
-    memset(udata, 0, sizeof(udata));
+    static char udata[PAGE_SIZE];
     hwc_context_t * ctx = reinterpret_cast<hwc_context_t *>(param);
-
+    char thread_name[64] = "hwcUeventThread";
+    prctl(PR_SET_NAME, (unsigned long) &thread_name, 0, 0, 0);
     setpriority(PRIO_PROCESS, 0, HAL_PRIORITY_URGENT_DISPLAY);
     uevent_init();