attemting to use dma not working

src/main.c

@@ -27,7 +27,20 @@ int main()
     uint offset = pio_add_program(lcd_config.pio, &tft_program);
     tft_program_init(lcd_config.pio, lcd_config.sm, offset, lcd_config.gpio_din, lcd_config.gpio_clk, 1.f);
 	
-	tft_init(&lcd_config);
+	int dma_chan = dma_claim_unused_channel(true);
+	dma_channel_config c = dma_channel_get_default_config(dma_chan);
+	channel_config_set_transfer_data_size(&c, DMA_SIZE_32);
+	channel_config_set_dreq(&c, DREQ_PIO0_TX0);
+	dma_channel_configure(
+		dma_chan,
+		&c,
+		&pio0_hw->txf[lcd_config.sm],
+		NULL,
+		4096,
+		false
+	);
+	
+	tft_init(&lcd_config, dma_chan);
 	
 	while (true) {
 		absolute_time_t start = get_absolute_time();	

src/tft.c

@@ -2,6 +2,7 @@
 
 static struct tft_config tft_cfg;
 static bool tft_data_mode = false;
+static int dma_chan;
 
 void tft_set_dc_cs(bool dc, bool cs) {
     sleep_us(1);
@@ -39,8 +40,9 @@ void tft_start_pixels(PIO pio, uint sm) {
     tft_set_dc_cs(1, 0);
 }
 
-void tft_init(const struct tft_config* config) {
+void tft_init(const struct tft_config* config, int dma_channel) {
 	memcpy(&tft_cfg, config, sizeof(tft_cfg));
+	dma_chan = dma_channel;
 
     gpio_init(tft_cfg.gpio_cs);
     gpio_init(tft_cfg.gpio_dc);
@@ -58,9 +60,13 @@ void tft_init(const struct tft_config* config) {
 }
 void tft_fill(uint16_t color) {
 	tft_start_pixels(tft_cfg.pio, tft_cfg.sm);
-	int num_pixels = tft_cfg.width * tft_cfg.height;
-	for (int i = 0; i < num_pixels; i++) {
-	    tft_put(tft_cfg.pio, tft_cfg.sm, color >> 8);
-	    tft_put(tft_cfg.pio, tft_cfg.sm, color & 0xff);
+	size_t buf_size = 4096;
+	uint16_t* pix_buf = malloc(buf_size * sizeof(uint16_t));	
+	size_t i;
+	for(i = 0; i < buf_size; i++) {
+		pix_buf[i] = color;
 	}
+	tft_push(tft_cfg.pio, tft_cfg.sm, dma_chan, pix_buf, buf_size);	
+	tft_push(tft_cfg.pio, tft_cfg.sm, dma_chan, pix_buf, buf_size);	
+	free(pix_buf);
 }

src/tft.h

@@ -4,6 +4,7 @@
 #include "hardware/gpio.h"
 #include "hardware/spi.h"
 #include "hardware/divider.h"
+#include "hardware/dma.h"
 #include "tft.pio.h"
 #include "pico/stdlib.h"
 #include <string.h>
@@ -41,6 +42,6 @@ void tft_set_dc_cs(bool dc, bool cs);
 void tft_write_cmd(PIO pio, uint sm, const uint8_t *cmd, size_t count);
 void lcd_init(PIO pio, uint sm, const uint8_t *init_seq);
 void tft_start_pixels(PIO pio, uint sm);
-void tft_init(const struct tft_config* config);
+void tft_init(const struct tft_config* config, int dma_channel);
 void tft_fill(uint16_t color);
 #endif // TFT_H

src/tft.pio

@@ -22,6 +22,8 @@
 // but we are using a threshold of 8 here (consume 1 byte from each FIFO entry
 // and discard the remainder) to make things easier for software on the other side
 
+#include <stdlib.h>
+
 static inline void tft_program_init(PIO pio, uint sm, uint offset, uint data_pin, uint clk_pin, float clk_div) {
     pio_gpio_init(pio, data_pin);
     pio_gpio_init(pio, clk_pin);
@@ -32,7 +34,7 @@ static inline void tft_program_init(PIO pio, uint sm, uint offset, uint data_pin
     sm_config_set_out_pins(&c, data_pin, 1);
     sm_config_set_fifo_join(&c, PIO_FIFO_JOIN_TX);
     sm_config_set_clkdiv(&c, clk_div);
-    sm_config_set_out_shift(&c, false, true, 8);
+    sm_config_set_out_shift(&c, false, true, 32);
     pio_sm_init(pio, sm, offset, &c);
     pio_sm_set_enabled(pio, sm, true);
 }
@@ -46,6 +48,19 @@ static inline void tft_put(PIO pio, uint sm, uint8_t x) {
     *(volatile uint8_t*)&pio->txf[sm] = x;
 }
 
+static inline void tft_push(PIO pio, uint sm, int dma_chan, uint16_t* pixels, size_t size) {
+    size_t new_size = size / 2;
+    uint32_t* x = malloc(new_size * sizeof(uint32_t));
+    
+    for (size_t i = 0, j = 0; i < size; i += 2, j++) {
+        uint32_t combinedValue = ((uint32_t)pixels[i] << 16) | pixels[i + 1];
+        x[j] = combinedValue;
+    }
+    dma_channel_set_read_addr(dma_chan, x, true);
+    sleep_ms(100);
+    free(x);
+}
+
 // SM is done when it stalls on an empty FIFO
 
 static inline void tft_wait_idle(PIO pio, uint sm) {