I've observed that "FIFO is overflown by GatherPipe" is not real overflow.

Really that happens because the fifo.CPReadWriteDistance is negative.
Example: CPReadWriteDistance: -864 CPEnd: 10092672 fifo.CPBase: 9568416
In SMG this is because  PI_FIFO_RESET is writing and after fifo.CPReadWriteDistance will be setted to 0.
To Prevent that, I've Implemented AbortFrame function in the CommmandProcessor. It should fix overflown because of that. 
Note: There is other issue (Issue 2846) where the fifo.CPReadWriteDistance is negative too but the effect is different.
I'm working to solve this.


git-svn-id: https://dolphin-emu.googlecode.com/svn/trunk@6083 8ced0084-cf51-0410-be5f-012b33b47a6e

Source/Core/VideoCommon/Src/CommandProcessor.cpp

@@ -701,4 +701,18 @@ void SetFifoIdleFromVideoPlugin()
 	s_fifoIdleEvent.Set();
 }
 
+// This is called by the ProcessorInterface when PI_FIFO_RESET is writed,
+// the general idea is abort all commands in the FIFO. 
+// This prevent Negative fifo.CPReadWriteDistance because when PI_FIFO_RESET happens
+// the fifo.CPReadWriteDistance is writed to 0
+void AbortFrame()
+{
+	Fifo_SetRendering(false);
+		while(!fifo.CPCmdIdle)
+			Common::YieldCPU();
+	Fifo_SetRendering(true);
+	PixelEngine::ResetSetToken();
+	PixelEngine::ResetSetFinish();
+}
+
 } // end of namespace CommandProcessor

Source/Core/VideoCommon/Src/CommandProcessor.h

@@ -162,6 +162,7 @@ void WaitForFrameFinish();
 void FifoCriticalEnter();
 void FifoCriticalLeave();
 
+void AbortFrame();
 } // namespace CommandProcessor
 
 #endif // _COMMANDPROCESSOR_H

Source/Core/VideoCommon/Src/PixelEngine.cpp

@@ -393,4 +393,16 @@ void ResetSetFinish()
 	}
 }
 
+void ResetSetToken()
+{
+	if (g_bSignalTokenInterrupt)
+	{
+		g_VideoInitialize.pSetInterrupt(INT_CAUSE_PE_TOKEN, false);
+		g_bSignalTokenInterrupt = false;
+		
+	}else
+	{
+		g_VideoInitialize.pRemoveEvent(et_SetTokenOnMainThread);
+	}
+}
 } // end of namespace PixelEngine

Source/Core/VideoCommon/Src/PixelEngine.h

@@ -68,6 +68,7 @@ void Write32(const u32 _iValue, const u32 _iAddress);
 void SetToken(const u16 _token, const int _bSetTokenAcknowledge);
 void SetFinish(void);
 void ResetSetFinish(void);
+void ResetSetToken(void);
 bool AllowIdleSkipping();
 
 // Bounding box functionality. Paper Mario (both) are a couple of the few games that use it.