From d9e2f85f98cd794c8288d0cd76697fb49ec7c666 Mon Sep 17 00:00:00 2001
From: mrfaptastic <12006953+mrfaptastic@users.noreply.github.com>
Date: Thu, 19 Aug 2021 19:22:29 +0100
Subject: [PATCH] Revert "Merge branch 'master' of
 https://github.com/mrfaptastic/ESP32-HUB75-MatrixPanel-I2S-DMA"

This reverts commit b6cbfce5dd3c99969eee8d506a6f9ecabbd81910, reversing
changes made to c5227fd15eb6138ed6dce9a3504110eed04cb938.
---
 ESP32-HUB75-MatrixPanel-I2S-DMA.h  | 34 ++++++++++++++++++------------
 ESP32-VirtualMatrixPanel-I2S-DMA.h |  4 +---
 2 files changed, 21 insertions(+), 17 deletions(-)

diff --git a/ESP32-HUB75-MatrixPanel-I2S-DMA.h b/ESP32-HUB75-MatrixPanel-I2S-DMA.h
index 927d428..f8648a1 100644
--- a/ESP32-HUB75-MatrixPanel-I2S-DMA.h
+++ b/ESP32-HUB75-MatrixPanel-I2S-DMA.h
@@ -388,7 +388,7 @@ class MatrixPanel_I2S_DMA {
       // Setup the ESP32 DMA Engine. Sprite_TM built this stuff.
       configureDMA(m_cfg); //DMA and I2S configuration and setup
 
-      flipDMABuffer(); // show backbuf_id of 0
+      showDMABuffer(); // show backbuf_id of 0
 
       #if SERIAL_DEBUG 
         if (!initialized)    
@@ -495,27 +495,33 @@ class MatrixPanel_I2S_DMA {
     inline void flipDMABuffer() 
     {         
       if ( !m_cfg.double_buff) return;
-
-        #if SERIAL_DEBUG
-                Serial.printf_P(PSTR("Showtime for buffer: %d\n"), back_buffer_id);
-        #endif
-      
-        i2s_parallel_flip_to_buffer(I2S_NUM_0, back_buffer_id);
-
+        
         // Flip to other buffer as the backbuffer. i.e. Graphic changes happen to this buffer (but aren't displayed until showDMABuffer())
         back_buffer_id ^= 1; 
         
-        #if SERIAL_DEBUG
+        #if SERIAL_DEBUG     
                 Serial.printf_P(PSTR("Set back buffer to: %d\n"), back_buffer_id);
-        #endif
+        #endif      
+
+        // Wait before we allow any writing to the buffer. Stop flicker.
+        while(!i2s_parallel_is_previous_buffer_free()) { delay(1); }       
     }
     
-    // stub function for compatibility
-    void showDMABuffer(){}
+    inline void showDMABuffer()
+    {
+      
+        if (!m_cfg.double_buff) return;
 
-    // check if backbuffer still has DMA transfer in progress or is it safe to write there
-    bool backbuffready(){ return i2s_parallel_is_previous_buffer_free(); }
+        #if SERIAL_DEBUG     
+                Serial.printf_P(PSTR("Showtime for buffer: %d\n"), back_buffer_id);
+        #endif      
+      
+        i2s_parallel_flip_to_buffer(I2S_NUM_0, back_buffer_id);
 
+        // Wait before we allow any writing to the buffer. Stop flicker.
+        while(!i2s_parallel_is_previous_buffer_free()) { delay(1); }               
+    }
+    
     inline void setPanelBrightness(int b)
     {
       // Change to set the brightness of the display, range of 1 to matrixWidth (i.e. 1 - 64)
diff --git a/ESP32-VirtualMatrixPanel-I2S-DMA.h b/ESP32-VirtualMatrixPanel-I2S-DMA.h
index 5ae1dac..c7b6a13 100644
--- a/ESP32-VirtualMatrixPanel-I2S-DMA.h
+++ b/ESP32-VirtualMatrixPanel-I2S-DMA.h
@@ -98,9 +98,7 @@ class VirtualMatrixPanel
     }
 	
 	void flipDMABuffer() { display->flipDMABuffer(); }
-	void showDMABuffer() {}
-  bool backbuffready(){ return display->backbuffready(); }
-
+	void showDMABuffer() { display->showDMABuffer(); }
 
     void drawDisplayTest();