video: stm32_dcmi: check for returned buffer at start of dequeue

If we had a timeout it would not check to see on next call if maybe it had completed.

Author: KurtE

drivers/video/video_stm32_dcmi.c

@@ -315,7 +315,7 @@ static int video_stm32_dcmi_enqueue(const struct device *dev, struct video_buffe
 {
 	struct video_stm32_dcmi_data *data = dev->data;
 	const uint32_t buffer_size = data->fmt.pitch * data->fmt.height;
-
+	printk("ENQ %p %p %u %u\n", vbuf, data, buffer_size, vbuf->size);
 	if (buffer_size > vbuf->size) {
 		return -EINVAL;
 	}
@@ -333,31 +333,35 @@ static int video_stm32_dcmi_dequeue(const struct device *dev, struct video_buffe
 {
 	struct video_stm32_dcmi_data *data = dev->data;
 
-	if (data->snapshot_mode) {
-		printk("dequeue snapshot: %p %llu\n", data->vbuf, timeout.ticks);
-		/* See if we were already called and have an active buffer */
-		if (data->vbuf == NULL) {
-			data->vbuf = k_fifo_get(&data->fifo_in, K_NO_WAIT);
-			printk("\tcamera buf: %p\n", data->vbuf);
+	/* check first to see if we already have a buffer returned */
+	*vbuf = k_fifo_get(&data->fifo_out, K_NO_WAIT);
+	printk("k_fifo_get returned: %p\n", *vbuf);
+	if (*vbuf == NULL) {
+		if (data->snapshot_mode) {
+			printk("dequeue snapshot: %p %llu\n", data->vbuf, timeout.ticks);
+			/* See if we were already called and have an active buffer */
 			if (data->vbuf == NULL) {
-				LOG_WRN("Snapshot: No Buffers available!");
-				return -ENOMEM;
+				data->vbuf = k_fifo_get(&data->fifo_in, K_NO_WAIT);
+				printk("\tcamera buf: %p\n", data->vbuf);
+				if (data->vbuf == NULL) {
+					LOG_WRN("Snapshot: No Buffers available!");
+					return -ENOMEM;
+				}
+
+				if (HAL_DCMI_Start_DMA(&data->hdcmi, DCMI_MODE_SNAPSHOT,
+						       (uint32_t)data->vbuf->buffer,
+						       data->vbuf->size / 4) != HAL_OK) {
+					LOG_WRN("Snapshot: HAL_DCMI_Start_DMA FAILED!");
+					return -EIO;
+				}
+			} else {
+				LOG_DBG("Snapshot: restart after timeout");
 			}
-
-			if (HAL_DCMI_Start_DMA(&data->hdcmi, DCMI_MODE_SNAPSHOT,
-					       (uint32_t)data->vbuf->buffer,
-					       data->vbuf->size / 4) != HAL_OK) {
-				LOG_WRN("Snapshot: HAL_DCMI_Start_DMA FAILED!");
-				return -EIO;
-			}
-		} else {
-			LOG_DBG("Snapshot: restart after timeout");
 		}
+		*vbuf = k_fifo_get(&data->fifo_out, timeout);
+		printk("k_fifo_get returned: %p\n", *vbuf);
 	}
 
-	*vbuf = k_fifo_get(&data->fifo_out, timeout);
-	printk("k_fifo_get returned: %p\n", *vbuf);
-
 	if (*vbuf == NULL) {
 		return -EAGAIN;
 	}