drivers: spi: stm32: dynamically update spi word/frame size

Update the source_data and dest_data sizes with the frame size
in bytes before performing the transfer.
With these changes, we can handle cases where the buffers switch
between 8-bit and 16-bit modes.

Signed-off-by: Fabrice DJIATSA <[email protected]>

Author: djiatsaf-st

drivers/spi/spi_ll_stm32.c

@@ -1186,6 +1186,13 @@ static int transceive_dma(const struct device *dev,
 	/* This is turned off in spi_stm32_complete(). */
 	spi_stm32_cs_control(dev, true);
 
+	uint8_t word_size_bytes = bits2bytes(SPI_WORD_SIZE_GET(config->operation));
+
+	data->dma_rx.dma_cfg.source_data_size = word_size_bytes;
+	data->dma_rx.dma_cfg.dest_data_size = word_size_bytes;
+	data->dma_tx.dma_cfg.source_data_size = word_size_bytes;
+	data->dma_tx.dma_cfg.dest_data_size = word_size_bytes;
+
 	while (data->ctx.rx_len > 0 || data->ctx.tx_len > 0) {
 		size_t dma_len;