linux-kernel - [PATCH 3/4] spi: spi-qcom-qspi: Call dma

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Message-Id: <1690285689-30233-4-git-send-email-quic_vnivarth@quicinc.com>
Date:   Tue, 25 Jul 2023 17:18:08 +0530
From:   Vijaya Krishna Nivarthi <quic_vnivarth@...cinc.com>
To:     agross@...nel.org, andersson@...nel.org, konrad.dybcio@...aro.org,
        broonie@...nel.org, linux-arm-msm@...r.kernel.org,
        linux-spi@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     quic_msavaliy@...cinc.com, dianders@...omium.org, mka@...omium.org,
        swboyd@...omium.org, quic_vtanuku@...cinc.com,
        dan.carpenter@...aro.org,
        Vijaya Krishna Nivarthi <quic_vnivarth@...cinc.com>
Subject: [PATCH 3/4] 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@...cinc.com>
---
 drivers/spi/spi-qcom-qspi.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi-qcom-qspi.c b/drivers/spi/spi-qcom-qspi.c
index b938908..d75234d 100644
--- 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");
-- 
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