[PATCH 17/18] spi: stm32: properly handle 0 byte transfer

[Alain Volmat]

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

Signed-off-by: Alain Volmat <alain.vol...@st.com>
---
 drivers/spi/spi-stm32.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/spi/spi-stm32.c b/drivers/spi/spi-stm32.c
index 177f82700de0..b909afd9e99b 100644
--- a/drivers/spi/spi-stm32.c
+++ b/drivers/spi/spi-stm32.c
@@ -1658,6 +1658,12 @@ static int stm32_spi_transfer_one(struct spi_master 
*master,
        unsigned long timeout;
        int ret;
 
+       /* Don't do anything on 0 bytes transfers */
+       if (transfer->len == 0) {
+               spi->xfer_status = 0;
+               goto finalize;
+       }
+
        spi->tx_buf = transfer->tx_buf;
        spi->rx_buf = transfer->rx_buf;
        spi->tx_len = spi->tx_buf ? transfer->len : 0;
@@ -1702,6 +1708,7 @@ static int stm32_spi_transfer_one(struct spi_master 
*master,
 
        spi->cfg->disable(spi);
 
+finalize:
        spi_finalize_current_transfer(master);
 
        return spi->xfer_status;
-- 
2.7.4