PSRAM works now on ESP32-S3

But it's pointless to use as the throughput can only be about 10Mhz.

src/ESP32-HUB75-MatrixPanel-I2S-DMA.cpp

@@ -1,5 +1,11 @@
 #include "ESP32-HUB75-MatrixPanel-I2S-DMA.h"
 
+#if defined(SPIRAM_DMA_BUFFER)
+  // Sprite_TM saves the day again...
+  // https://www.esp32.com/viewtopic.php?f=2&t=30584
+  #include "rom/cache.h"
+#endif 
+
 static const char* TAG = "MatrixPanel";
 
 /* This replicates same function in rowBitStruct, but due to induced inlining it might be MUCH faster 
@@ -249,6 +255,10 @@ void MatrixPanel_I2S_DMA::configureDMA(const HUB75_I2S_CFG& _cfg)
       bus_cfg.pin_d14  = -1;
       bus_cfg.pin_d15  = -1;
 
+      #if defined(SPIRAM_DMA_BUFFER)      
+        bus_cfg.psram_clk_hack = true;
+      #endif
+
       dma_bus.config(bus_cfg);   
 
       dma_bus.init();      
@@ -368,6 +378,10 @@ void IRAM_ATTR MatrixPanel_I2S_DMA::updateMatrixDMABuffer(uint16_t x_coord, uint
         p[x_coord] &= _colourbitclear;   // reset RGB bits
         p[x_coord] |= RGB_output_bits;  // set new RGB bits
 
+        #if defined(SPIRAM_DMA_BUFFER)          
+            Cache_WriteBack_Addr((uint32_t)&p[x_coord], sizeof(ESP32_I2S_DMA_STORAGE_TYPE)) ;
+        #endif 
+
     } while(colour_depth_idx);  // end of colour depth loop (8)
 } // updateMatrixDMABuffer (specific co-ords change)
 
@@ -424,6 +438,12 @@ void MatrixPanel_I2S_DMA::updateMatrixDMABuffer(uint8_t red, uint8_t green, uint
         --x_coord;
         p[x_coord] &= BITMASK_RGB12_CLEAR;  // reset colour bits
         p[x_coord] |= RGB_output_bits;      // set new colour bits
+
+
+        #if defined(SPIRAM_DMA_BUFFER)          
+            Cache_WriteBack_Addr((uint32_t)&p[x_coord], sizeof(ESP32_I2S_DMA_STORAGE_TYPE)) ;
+        #endif 
+
       } while(x_coord);
 
     } while(matrix_frame_parallel_row); // end row iteration
@@ -557,6 +577,13 @@ void MatrixPanel_I2S_DMA::clearFrameBuffer(bool _buff_id){
 
     } while(colouridx);
 
+
+
+    #if defined(SPIRAM_DMA_BUFFER)          
+        Cache_WriteBack_Addr((uint32_t)row, sizeof(ESP32_I2S_DMA_STORAGE_TYPE) * ((dma_buff.rowBits[row_idx]->width * dma_buff.rowBits[row_idx]->colour_depth)-1)) ;
+    #endif 
+    
+
   } while(row_idx);
 }
 
@@ -632,12 +659,21 @@ void MatrixPanel_I2S_DMA::brtCtrlOE(int brt, const bool _buff_id){
       row[ESP32_TX_FIFO_POSITION_ADJUST(0 + _blank)] |= BIT_OE;    
       
 
+
         //row[0 + _blank] |= BIT_OE;
         // no need, has been done already
         //row[dma_buff.rowBits[row_idx]->width - _blank - 3 ] |= BIT_OE;    // (LAT pulse is (width-2) -1 pixel to compensate array index starting at 0
       } while (_blank);
 
     } while(colouridx);
+
+    // switch pointer to a row for a specific color index
+    #if defined(SPIRAM_DMA_BUFFER)          
+        ESP32_I2S_DMA_STORAGE_TYPE* row_hack = dma_buff.rowBits[row_idx]->getDataPtr(colouridx, _buff_id);    
+        Cache_WriteBack_Addr((uint32_t)row_hack, sizeof(ESP32_I2S_DMA_STORAGE_TYPE) * ((dma_buff.rowBits[row_idx]->width * dma_buff.rowBits[row_idx]->colour_depth)-1)) ;
+    #endif 
+
+
   } while(row_idx);
 }
 

src/ESP32-HUB75-MatrixPanel-I2S-DMA.h

@@ -142,9 +142,12 @@ struct rowBitStruct {
     // constructor - allocates DMA-capable memory to hold the struct data
     rowBitStruct(const size_t _width, const uint8_t _depth, const bool _dbuff) : width(_width), colour_depth(_depth), double_buff(_dbuff) {
 
-#if defined(SPIRAM_FRAMEBUFFER) && defined (CONFIG_IDF_TARGET_ESP32S3)     
+//#if defined(SPIRAM_FRAMEBUFFER) && defined (CONFIG_IDF_TARGET_ESP32S3)     
-      #pragma message "Enabling PSRAM / SPIRAM for frame buffer."
+  #if defined(SPIRAM_DMA_BUFFER)
-      data = (ESP32_I2S_DMA_STORAGE_TYPE *)heap_caps_malloc( size()+size()*double_buff, MALLOC_CAP_SPIRAM);
+    //  #pragma message "Enabling PSRAM / SPIRAM for frame buffer."
+    //  ESP_LOGI("rowBitStruct", "Allocated DMA BitBuffer from PSRAM (SPIRAM)");
+      //data = (ESP32_I2S_DMA_STORAGE_TYPE *)heap_caps_malloc( size()+size()*double_buff, MALLOC_CAP_SPIRAM);
+      data = (ESP32_I2S_DMA_STORAGE_TYPE *)heap_caps_aligned_alloc(64, size()+size()*double_buff, MALLOC_CAP_SPIRAM | MALLOC_CAP_8BIT);
 /*
       if (!psramFound())      
       {
@@ -153,6 +156,7 @@ struct rowBitStruct {
 */
 #else
       data = (ESP32_I2S_DMA_STORAGE_TYPE *)heap_caps_malloc( size()+size()*double_buff, MALLOC_CAP_INTERNAL | MALLOC_CAP_DMA);
+   //   ESP_LOGI("rowBitStruct", "Allocated DMA BitBuffer from regular (and limited) SRAM");      
 #endif
 
     }

src/platforms/esp32s3/gdma_lcd_parallel16.cpp

@@ -79,9 +79,12 @@
     LCD_CAM.lcd_user.lcd_reset = 1;
     esp_rom_delay_us(100);
 
-    uint32_t lcd_clkm_div_num = ((160000000 + 1) / _cfg.bus_freq) / 2;
+//    uint32_t lcd_clkm_div_num = ((160000000 + 1) / _cfg.bus_freq);
+     ESP_LOGI(TAG, "Cpu frequecny is %d", getCpuFrequencyMhz());
 
-     ESP_LOGI(TAG, "Clock divider is %d", lcd_clkm_div_num);
+     uint32_t lcd_clkm_div_num = (  ((getCpuFrequencyMhz()*1000000)+1) /  _cfg.bus_freq  ) / 4;
+
+     //ESP_LOGI(TAG, "Clock divider is %d", lcd_clkm_div_num);     
 
     // Configure LCD clock. Since this program generates human-perceptible
     // output and not data for LED matrices or NeoPixels, use almost the
@@ -90,12 +93,27 @@
     // is applied (250*64), yielding 2,500 Hz. Still much too fast for
     // human eyes, so later we set up the data to repeat each output byte
     // many times over.
-    LCD_CAM.lcd_clock.clk_en = 1;             // Enable peripheral clock
+    //LCD_CAM.lcd_clock.clk_en = 0;             // Enable peripheral clock
-    LCD_CAM.lcd_clock.lcd_clk_sel = 2;        // 160mhz source
+
+    // LCD_CAM_LCD_CLK_SEL Select LCD module source clock. 0: clock source is disabled. 1: XTAL_CLK. 2: PLL_D2_CLK. 3: PLL_F160M_CLK. (R/W)
+    LCD_CAM.lcd_clock.lcd_clk_sel = 2;        
     LCD_CAM.lcd_clock.lcd_ck_out_edge = 0;    // PCLK low in 1st half cycle
     LCD_CAM.lcd_clock.lcd_ck_idle_edge = 0;   // PCLK low idle
     LCD_CAM.lcd_clock.lcd_clk_equ_sysclk = 0; // PCLK = CLK / (CLKCNT_N+1)
-    LCD_CAM.lcd_clock.lcd_clkm_div_num = lcd_clkm_div_num; // 1st stage 1:250 divide
+
+
+    if (_cfg.psram_clk_hack) // fastest speed I can get PSRAM to work before nothing shows
+    {
+      LCD_CAM.lcd_clock.lcd_clkm_div_num = 4; 
+    }
+    else
+    {
+      //LCD_CAM.lcd_clock.lcd_clkm_div_num = lcd_clkm_div_num;      
+      LCD_CAM.lcd_clock.lcd_clkm_div_num = 3;      
+    }
+     ESP_LOGI(TAG, "Clock divider is %d", LCD_CAM.lcd_clock.lcd_clkm_div_num);     
+
+    
     LCD_CAM.lcd_clock.lcd_clkm_div_a = 1;     // 0/1 fractional divide
     LCD_CAM.lcd_clock.lcd_clkm_div_b = 0;
     
@@ -194,8 +212,8 @@
     gdma_apply_strategy(dma_chan, &strategy_config);
 
     gdma_transfer_ability_t ability = {
-        .sram_trans_align = 0,
+        .sram_trans_align = 4,
-        .psram_trans_align = 0,
+        .psram_trans_align = 64,
     };
     gdma_set_transfer_ability(dma_chan, &ability);    
 

src/platforms/esp32s3/gdma_lcd_parallel16.hpp

@@ -101,11 +101,12 @@
       //int port = 0;
 
       // max 40MHz (when in 16 bit / 2 byte mode)
-      uint32_t bus_freq = 20000000;
+      uint32_t bus_freq = 10000000;
       int8_t pin_wr = -1;
       int8_t pin_rd = -1;
       int8_t pin_rs = -1;  // D/C
       bool   invert_pclk = false;
+      bool   psram_clk_hack = false;
       union
       {
         int8_t pin_data[16];

src/platforms/platform_detect.hpp

@@ -39,6 +39,14 @@ Modified heavily for the ESP32 HUB75 DMA library by:
   #include "esp32s3/gdma_lcd_parallel16.hpp"
   #include "esp32s3/esp32s3-default-pins.hpp"    
 
+  #if defined(SPIRAM_FRAMEBUFFER) && defined (CONFIG_IDF_TARGET_ESP32S3)       
+   #pragma message "Enabling use of PSRAM/SPIRAM based DMA Buffer"
+   #define SPIRAM_DMA_BUFFER 1
+   
+   // Disable fast functions because I don't understand the interaction with DMA PSRAM and the CPU->DMA->SPIRAM Cache implications..
+   #define NO_FAST_FUNCTIONS 1
+  #endif
+
  #elif defined(CONFIG_IDF_TARGET_ESP32C3) || defined(CONFIG_IDF_TARGET_ESP32H2)
 
 	#error "ESP32 RISC-V devices do not have an LCD interface and are therefore not supported by this library."