[PATCH v2] spi: spi-cadence-quadspi: Fix mapping of buffers for DMA reads

[Vignesh Raghavendra]

Buffers need to mapped to DMA channel's device pointer instead of SPI
controller's device pointer as its system DMA that actually does data
transfer.
Data inconsistencies have been reported when reading from flash
without this fix.

Fixes: ffa639e069fb ("mtd: spi-nor: cadence-quadspi: Add DMA support for direct 
mode reads")
Signed-off-by: Vignesh Raghavendra <vigne...@ti.com>
Tested-by: Jan Kiszka <jan.kis...@siemens.com>
---

v2:
Update the Fixes tag and add collect tested-by

 drivers/spi/spi-cadence-quadspi.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/spi/spi-cadence-quadspi.c 
b/drivers/spi/spi-cadence-quadspi.c
index 508b219eabf8..c6795c684b16 100644
--- a/drivers/spi/spi-cadence-quadspi.c
+++ b/drivers/spi/spi-cadence-quadspi.c
@@ -907,14 +907,16 @@ static int cqspi_direct_read_execute(struct 
cqspi_flash_pdata *f_pdata,
        struct dma_async_tx_descriptor *tx;
        dma_cookie_t cookie;
        dma_addr_t dma_dst;
+       struct device *ddev;
 
        if (!cqspi->rx_chan || !virt_addr_valid(buf)) {
                memcpy_fromio(buf, cqspi->ahb_base + from, len);
                return 0;
        }
 
-       dma_dst = dma_map_single(dev, buf, len, DMA_FROM_DEVICE);
-       if (dma_mapping_error(dev, dma_dst)) {
+       ddev = cqspi->rx_chan->device->dev;
+       dma_dst = dma_map_single(ddev, buf, len, DMA_FROM_DEVICE);
+       if (dma_mapping_error(ddev, dma_dst)) {
                dev_err(dev, "dma mapping failed\n");
                return -ENOMEM;
        }
@@ -948,7 +950,7 @@ static int cqspi_direct_read_execute(struct 
cqspi_flash_pdata *f_pdata,
        }
 
 err_unmap:
-       dma_unmap_single(dev, dma_dst, len, DMA_FROM_DEVICE);
+       dma_unmap_single(ddev, dma_dst, len, DMA_FROM_DEVICE);
 
        return ret;
 }
-- 
2.28.0