tests: spi_loopback: kinetis dspi fix

1. kenistis dspi does support rx and tx with different size,
so skip the tx_bigger test.
2. dspi dma need internal alignment and 8192 bytes are too
many for k64, so reduce to 1440 bytes

fixing: #77010

Signed-off-by: Hake Huang <[email protected]>

Author: hakehuang

tests/drivers/spi/spi_loopback/overlay-mcux-dspi-dma.conf

@@ -1,4 +1,4 @@
 # enable DMA mode
 CONFIG_DMA=y
 CONFIG_DSPI_MCUX_EDMA=y
-CONFIG_MCUX_DSPI_BUFFER_SIZE=144
+CONFIG_MCUX_DSPI_BUFFER_SIZE=5760

tests/drivers/spi/spi_loopback/src/spi.c

@@ -58,7 +58,14 @@ static struct spi_dt_spec spi_slow = SPI_DT_SPEC_GET(SPI_SLOW_DEV, SPI_OP(FRAME_
 #define STACK_SIZE (512 + CONFIG_TEST_EXTRA_STACK_SIZE)
 #define BUF_SIZE 18
 #define BUF2_SIZE 36
+
+#ifdef CONFIG_DSPI_MCUX_EDMA
+/*DSPI DMA need aligned buffer for internal*/
+#define BUF3_SIZE 1440
+#else
 #define BUF3_SIZE 8192
+#endif
+
 
 #if CONFIG_NOCACHE_MEMORY
 #define __NOCACHE	__attribute__((__section__(".nocache")))
@@ -481,6 +488,11 @@ static int spi_rx_bigger_than_tx(struct spi_dt_spec *spec)
 		return 0;
 	}
 
+	if (IS_ENABLED(CONFIG_DSPI_MCUX_EDMA)) {
+		LOG_INF("Skip rx bigger than tx");
+		return 0;
+	}
+
 	LOG_INF("Start rx bigger than tx");
 
 	(void)memset(buffer_rx, 0xff, BUF_SIZE);