diff --git a/linux_various/glsl2h.pl b/linux_various/glsl2h.pl
index 15aabc28e0..36c3abc73a 100755
--- a/linux_various/glsl2h.pl
+++ b/linux_various/glsl2h.pl
@@ -2,9 +2,10 @@
 
 use strict;
 use warnings;
+use File::Spec;
 
 my @res = qw/convert interlace merge shadeboost tfx/;
-my $path = "plugins/GSdx/res";
+my $path = File::Spec->catdir("plugins", "GSdx", "res");
 
 foreach my $r (@res) {
     glsl2h($path, $r);
@@ -14,8 +15,10 @@ sub glsl2h {
     my $path = shift;
     my $glsl = shift;
 
-    open(my $GLSL, "<$path/${glsl}.glsl");
-    open(my $H, ">$path/${glsl}.h");
+    my $in = File::Spec->catfile($path, "${glsl}.glsl");
+    my $out = File::Spec->catfile($path, "${glsl}.h");
+    open(my $GLSL, "<$in") or die;
+    open(my $H, ">$out") or die;
 
     my $header = <<EOS;
 /*
diff --git a/plugins/GSdx/CMakeLists.txt b/plugins/GSdx/CMakeLists.txt
index c61e5cbc3b..49b36de6e6 100644
--- a/plugins/GSdx/CMakeLists.txt
+++ b/plugins/GSdx/CMakeLists.txt
@@ -18,7 +18,6 @@ set(CommonFlags
     -Wunused-variable
     -std=c++0x
     -fno-strict-aliasing
-    #-DENABLE_OGL_DEBUG # FIXME remove me when code is ready
     )
 
 set(OptimizationFlags
@@ -28,7 +27,7 @@ set(OptimizationFlags
 
 # Debug - Build
 if(CMAKE_BUILD_TYPE STREQUAL Debug)
-    add_definitions(${CommonFlags} -DENABLE_OGL_DEBUG -g -Wall)
+    add_definitions(${CommonFlags} -D_DEBUG -g -Wall)
 endif(CMAKE_BUILD_TYPE STREQUAL Debug)
 
 # Devel - Build
diff --git a/plugins/GSdx/GLLoader.cpp b/plugins/GSdx/GLLoader.cpp
index c08d1c05d2..3b28ba93ab 100644
--- a/plugins/GSdx/GLLoader.cpp
+++ b/plugins/GSdx/GLLoader.cpp
@@ -85,6 +85,7 @@ PFNGLUSEPROGRAMSTAGESPROC              gl_UseProgramStages            = NULL;
 PFNGLVERTEXATTRIBIPOINTERPROC          gl_VertexAttribIPointer        = NULL;
 PFNGLVERTEXATTRIBPOINTERPROC           gl_VertexAttribPointer         = NULL;
 PFNGLTEXSTORAGE2DPROC                  gl_TexStorage2D                = NULL;
+PFNGLBUFFERSUBDATAPROC                 gl_BufferSubData               = NULL;
 // NO GL4.1
 PFNGLUSEPROGRAMPROC                    gl_UseProgram                  = NULL;
 PFNGLGETSHADERINFOLOGPROC              gl_GetShaderInfoLog            = NULL;
@@ -207,6 +208,7 @@ namespace GLLoader {
 		GL_LOADFN(gl_VertexAttribIPointer, glVertexAttribIPointer);
 		GL_LOADFN(gl_VertexAttribPointer, glVertexAttribPointer);
 		GL_LOADFN(gl_TexStorage2D, glTexStorage2D);
+		GL_LOADFN(gl_BufferSubData, glBufferSubData);
 		// NO GL4.1
 		GL_LOADFN(gl_UseProgram, glUseProgram);
 		GL_LOADFN(gl_GetShaderInfoLog, glGetShaderInfoLog);
diff --git a/plugins/GSdx/GLLoader.h b/plugins/GSdx/GLLoader.h
index c241b8e552..c388eb5d8a 100644
--- a/plugins/GSdx/GLLoader.h
+++ b/plugins/GSdx/GLLoader.h
@@ -111,6 +111,7 @@ extern   PFNGLUSEPROGRAMSTAGESPROC              gl_UseProgramStages;
 extern   PFNGLVERTEXATTRIBIPOINTERPROC          gl_VertexAttribIPointer;
 extern   PFNGLVERTEXATTRIBPOINTERPROC           gl_VertexAttribPointer;
 extern   PFNGLTEXSTORAGE2DPROC                  gl_TexStorage2D;
+extern   PFNGLBUFFERSUBDATAPROC                 gl_BufferSubData;
 // NO GL4.1
 extern   PFNGLUSEPROGRAMPROC                    gl_UseProgram;
 extern   PFNGLGETSHADERINFOLOGPROC              gl_GetShaderInfoLog;
diff --git a/plugins/GSdx/GSUniformBufferOGL.h b/plugins/GSdx/GSUniformBufferOGL.h
index fea75ab946..dedc037156 100644
--- a/plugins/GSdx/GSUniformBufferOGL.h
+++ b/plugins/GSdx/GSUniformBufferOGL.h
@@ -55,10 +55,10 @@ public:
 
 	void upload(const void* src)
 	{
-		uint32 flags = GL_MAP_WRITE_BIT | GL_MAP_INVALIDATE_BUFFER_BIT;
-		uint8* dst = (uint8*) gl_MapBufferRange(target, 0, size, flags);
-		memcpy(dst, src, size);
-		gl_UnmapBuffer(target);
+		// glMapBufferRange allow to set various parameter but the call is
+		// synchronous whereas glBufferSubData could be asynchronous.
+		// TODO: investigate the extension ARB_invalidate_subdata
+		gl_BufferSubData(target, 0, size, src);
 	}
 
 	~GSUniformBufferOGL() {
diff --git a/plugins/GSdx/GSWndEGL.cpp b/plugins/GSdx/GSWndEGL.cpp
index 6113dabf4b..4a960139db 100644
--- a/plugins/GSdx/GSWndEGL.cpp
+++ b/plugins/GSdx/GSWndEGL.cpp
@@ -103,6 +103,10 @@ bool GSWndEGL::CreateContext(int major, int minor)
 void GSWndEGL::AttachContext()
 {
 	if (!IsContextAttached()) {
+		// The setting of the API is local to a thread. This function 
+		// can be called from 2 threads.
+		eglBindAPI(EGL_OPENGL_API);
+
 		//fprintf(stderr, "Attach the context\n");
 		eglMakeCurrent(m_eglDisplay, m_eglSurface, m_eglSurface, m_eglContext);
 		m_ctx_attached = true;
diff --git a/plugins/GSdx/res/tfx.glsl b/plugins/GSdx/res/tfx.glsl
index 36017dd420..98f0fe52ea 100644
--- a/plugins/GSdx/res/tfx.glsl
+++ b/plugins/GSdx/res/tfx.glsl
@@ -526,14 +526,14 @@ vec4 sample_color(vec2 st, float q)
         if((PS_FMT & ~FMT_PAL) == FMT_24)
         {
             // FIXME GLSL any only support bvec so try to mix it with notEqual
-            bvec3 rgb_check = notEqual( t.rgb, vec3(0.0f, 0.0f, 0.0f) );
-            t.a = ( (PS_AEM == 0) || any(rgb_check)  ) ? TA.x : 0.0f;
+            bvec3 rgb_check = notEqual( c[i].rgb, vec3(0.0f, 0.0f, 0.0f) );
+            c[i].a = ( (PS_AEM == 0) || any(rgb_check)  ) ? TA.x : 0.0f;
         }
         else if((PS_FMT & ~FMT_PAL) == FMT_16)
         {
             // FIXME GLSL any only support bvec so try to mix it with notEqual
-            bvec3 rgb_check = notEqual( t.rgb, vec3(0.0f, 0.0f, 0.0f) );
-            t.a = t.a >= 0.5 ? TA.y : ( (PS_AEM == 0) || any(rgb_check) ) ? TA.x : 0.0f;
+            bvec3 rgb_check = notEqual( c[i].rgb, vec3(0.0f, 0.0f, 0.0f) );
+            c[i].a = c[i].a >= 0.5 ? TA.y : ( (PS_AEM == 0) || any(rgb_check) ) ? TA.x : 0.0f;
         }
     }
 
diff --git a/plugins/GSdx/res/tfx.h b/plugins/GSdx/res/tfx.h
index c6f0216259..7404d405b9 100644
--- a/plugins/GSdx/res/tfx.h
+++ b/plugins/GSdx/res/tfx.h
@@ -554,14 +554,14 @@ static const char* tfx_glsl =
 	"        if((PS_FMT & ~FMT_PAL) == FMT_24)\n"
 	"        {\n"
 	"            // FIXME GLSL any only support bvec so try to mix it with notEqual\n"
-	"            bvec3 rgb_check = notEqual( t.rgb, vec3(0.0f, 0.0f, 0.0f) );\n"
-	"            t.a = ( (PS_AEM == 0) || any(rgb_check)  ) ? TA.x : 0.0f;\n"
+	"            bvec3 rgb_check = notEqual( c[i].rgb, vec3(0.0f, 0.0f, 0.0f) );\n"
+	"            c[i].a = ( (PS_AEM == 0) || any(rgb_check)  ) ? TA.x : 0.0f;\n"
 	"        }\n"
 	"        else if((PS_FMT & ~FMT_PAL) == FMT_16)\n"
 	"        {\n"
 	"            // FIXME GLSL any only support bvec so try to mix it with notEqual\n"
-	"            bvec3 rgb_check = notEqual( t.rgb, vec3(0.0f, 0.0f, 0.0f) );\n"
-	"            t.a = t.a >= 0.5 ? TA.y : ( (PS_AEM == 0) || any(rgb_check) ) ? TA.x : 0.0f;\n"
+	"            bvec3 rgb_check = notEqual( c[i].rgb, vec3(0.0f, 0.0f, 0.0f) );\n"
+	"            c[i].a = c[i].a >= 0.5 ? TA.y : ( (PS_AEM == 0) || any(rgb_check) ) ? TA.x : 0.0f;\n"
 	"        }\n"
 	"    }\n"
 	"\n"