spi: spi-qcom-qspi: Call dma_wmb() after setting up descriptors

After setting up dma descriptors and before initiaiting dma transfer, call
dma_wmb() to ensure all writes go through.
This doesn't fix any reported problem but is added for safety.

Signed-off-by: Vijaya Krishna Nivarthi <quic_vnivarth@quicinc.com>
Fixes: b5762d95607e ("spi: spi-qcom-qspi: Add DMA mode support")
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/1690285689-30233-4-git-send-email-quic_vnivarth@quicinc.com
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/drivers/spi/spi-qcom-qspi.c b/drivers/spi/spi-qcom-qspi.c
index 67c1017..75fcb91 100644 (file)
--- a/drivers/spi/spi-qcom-qspi.c
+++ b/drivers/spi/spi-qcom-qspi.c
@@ -443,8 +443,10 @@ static int qcom_qspi_transfer_one(struct spi_master *master,
 
                ret = qcom_qspi_setup_dma_desc(ctrl, xfer);
                if (ret != -EAGAIN) {
-                       if (!ret)
+                       if (!ret) {
+                               dma_wmb();
                                qcom_qspi_dma_xfer(ctrl);
+                       }
                        goto exit;
                }
                dev_warn_once(ctrl->dev, "DMA failure, falling back to PIO\n");