drivers: spi_mcux_lpspi: Remove rtio prepare_start

Remove unneeded prepare_start function since all uses of it are paired
with the start function. Also, probably should not mess with chip select
before deciding to do the transfer. And just return on some error like
the rest of the driver does instead of assert.

Signed-off-by: Declan Snyder <declan.snyder@nxp.com>

Author: decsny

drivers/spi/spi_mcux_lpspi.c

@@ -527,20 +527,6 @@ static int transceive_dma(const struct device *dev, const struct spi_config *spi
 #endif /* CONFIG_SPI_MCUX_LPSPI_DMA */
 
 #ifdef CONFIG_SPI_RTIO
-static inline void spi_mcux_iodev_prepare_start(const struct device *dev)
-{
-	struct spi_mcux_data *data = dev->data;
-	struct spi_rtio *rtio_ctx = data->rtio_ctx;
-	struct spi_dt_spec *spi_dt_spec = rtio_ctx->txn_curr->sqe.iodev->data;
-	struct spi_config *spi_config = &spi_dt_spec->config;
-	int err;
-
-	err = spi_mcux_configure(dev, spi_config);
-	__ASSERT(!err, "%d", err);
-
-	spi_context_cs_control(&data->ctx, true);
-}
-
 static void spi_mcux_iodev_start(const struct device *dev)
 {
 	struct spi_mcux_data *data = dev->data;
@@ -552,6 +538,12 @@ static void spi_mcux_iodev_start(const struct device *dev)
 	lpspi_transfer_t transfer;
 	status_t status;
 
+	status = spi_mcux_configure(dev, spi_cfg);
+	if (status) {
+		LOG_ERR("Error configuring lpspi");
+		return;
+	}
+
 	transfer.configFlags = LPSPI_MASTER_XFER_CFG_FLAGS(spi_cfg->slave);
 
 	switch (sqe->op) {
@@ -583,6 +575,8 @@ static void spi_mcux_iodev_start(const struct device *dev)
 
 	data->transfer_len = transfer.dataSize;
 
+	spi_context_cs_control(&data->ctx, true);
+
 	status = LPSPI_MasterTransferNonBlocking(base, &data->handle, &transfer);
 	if (status != kStatus_Success) {
 		LOG_ERR("Transfer could not start on %s: %d", dev->name, status);
@@ -605,7 +599,6 @@ static void spi_mcux_iodev_complete(const struct device *dev, int status)
 	spi_context_cs_control(&data->ctx, false);
 
 	if (spi_rtio_complete(rtio_ctx, status)) {
-		spi_mcux_iodev_prepare_start(dev);
 		spi_mcux_iodev_start(dev);
 	}
 }
@@ -616,7 +609,6 @@ static void spi_mcux_iodev_submit(const struct device *dev, struct rtio_iodev_sq
 	struct spi_rtio *rtio_ctx = data->rtio_ctx;
 
 	if (spi_rtio_submit(rtio_ctx, iodev_sqe)) {
-		spi_mcux_iodev_prepare_start(dev);
 		spi_mcux_iodev_start(dev);
 	}
 }