drivers: spi: stm32: fix full duplex asynchronous transfer

For an asynchronous transfer, the driver was waiting until transfer was
ended to leave the transceive function, which defeated the purpose of
async. Restore previous behavior. The transfer is still blocking for
half duplex though.

Signed-off-by: Guillaume Gautier <guillaume.gautier-ext@st.com>

Author: gautierg-st

drivers/spi/spi_stm32.c

@@ -1421,7 +1421,8 @@ static int transceive(const struct device *dev,
 			ret = spi_stm32_half_duplex_switch_to_receive(cfg, data);
 			transfer_dir = LL_SPI_GetTransferDirection(spi);
 		}
-	} while (ret == 0 && spi_stm32_transfer_ongoing(data));
+	} while (ret == 0 && spi_stm32_transfer_ongoing(data) &&
+		 transfer_dir != LL_SPI_FULL_DUPLEX);
 #else /* CONFIG_SPI_STM32_INTERRUPT */
 	while (ret == 0 && spi_stm32_transfer_ongoing(data)) {
 		ret = spi_stm32_shift_frames(cfg, data);