cmd: sf: Print error on test failure

The sf test command is used to test spi flashes (and spi masters). Printing
the exact error code is very helpful to those debugging the spi stack.

Signed-off-by: Sean Anderson <seanga2@gmail.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Pratyush Yadav <p.yadav@ti.com>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>

cmd/sf.c

@@ -445,20 +445,22 @@ static int spi_flash_test(struct spi_flash *flash, uint8_t *buf, ulong len,
 			   ulong offset, uint8_t *vbuf)
 {
 	struct test_info test;
-	int i;
+	int err, i;
 
 	printf("SPI flash test:\n");
 	memset(&test, '\0', sizeof(test));
 	test.base_ms = get_timer(0);
 	test.bytes = len;
-	if (spi_flash_erase(flash, offset, len)) {
-		printf("Erase failed\n");
+	err = spi_flash_erase(flash, offset, len);
+	if (err) {
+		printf("Erase failed (err = %d)\n", err);
 		return -1;
 	}
 	spi_test_next_stage(&test);
 
-	if (spi_flash_read(flash, offset, len, vbuf)) {
-		printf("Check read failed\n");
+	err = spi_flash_read(flash, offset, len, vbuf);
+	if (err) {
+		printf("Check read failed (err = %d)\n", err);
 		return -1;
 	}
 	for (i = 0; i < len; i++) {
@@ -471,15 +473,17 @@ static int spi_flash_test(struct spi_flash *flash, uint8_t *buf, ulong len,
 	}
 	spi_test_next_stage(&test);
 
-	if (spi_flash_write(flash, offset, len, buf)) {
-		printf("Write failed\n");
+	err = spi_flash_write(flash, offset, len, buf);
+	if (err) {
+		printf("Write failed (err = %d)\n", err);
 		return -1;
 	}
 	memset(vbuf, '\0', len);
 	spi_test_next_stage(&test);
 
-	if (spi_flash_read(flash, offset, len, vbuf)) {
-		printf("Read failed\n");
+	err = spi_flash_read(flash, offset, len, vbuf);
+	if (err) {
+		printf("Read failed (ret = %d)\n", err);
 		return -1;
 	}
 	spi_test_next_stage(&test);