[PATCH 1/8] spi: stm32: properly handle 0 byte transfer

[Alain Volmat <alain.volmat@xxxxxxxxxxx>]

On 0 byte transfer request, return straight from the
xfer function after finalizing the transfer.

Fixes: dcbe0d84dfa5 ("spi: add driver for STM32 SPI controller")
Signed-off-by: Alain Volmat <alain.volmat@xxxxxxxxxxx>
---
 drivers/spi/spi-stm32.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/spi/spi-stm32.c b/drivers/spi/spi-stm32.c
index db3e305d9ec4..137213633e6d 100644
--- a/drivers/spi/spi-stm32.c
+++ b/drivers/spi/spi-stm32.c
@@ -1657,6 +1657,12 @@ static int stm32_spi_transfer_one(struct spi_master *master,
 	struct stm32_spi *spi = spi_master_get_devdata(master);
 	int ret;
 
+	/* Don't do anything on 0 bytes transfers */
+	if (transfer->len == 0) {
+		spi_finalize_current_transfer(master);
+		return 0;
+	}
+
 	spi->tx_buf = transfer->tx_buf;
 	spi->rx_buf = transfer->rx_buf;
 	spi->tx_len = spi->tx_buf ? transfer->len : 0;
-- 
2.17.1