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Subject[PATCH 3/4] spi: spi-fsl-dspi: Fix continuous selection format
Date
Current DMA implementation was not handling the continuous selection
format viz. SPI chip select would be deasserted even between sequential
serial transfers. Use the cs_change variable and correctly set or
reset the CONT bit accordingly for case where peripherals require
the chip select to be asserted between sequential transfers.

Signed-off-by: Sanchayan Maity <maitysanchayan@gmail.com>
---
drivers/spi/spi-fsl-dspi.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/spi/spi-fsl-dspi.c b/drivers/spi/spi-fsl-dspi.c
index aee8c88..164e2e1 100644
--- a/drivers/spi/spi-fsl-dspi.c
+++ b/drivers/spi/spi-fsl-dspi.c
@@ -258,9 +258,16 @@ static int dspi_next_xfer_dma_submit(struct fsl_dspi *dspi)
}

val = tx_word ? *(u16 *) dspi->tx : *(u8 *) dspi->tx;
- dspi->dma->tx_dma_buf[i] = SPI_PUSHR_TXDATA(val) |
- SPI_PUSHR_PCS(dspi->cs) |
- SPI_PUSHR_CTAS(0);
+ if (dspi->cs_change) {
+ dspi->dma->tx_dma_buf[i] = SPI_PUSHR_TXDATA(val) |
+ SPI_PUSHR_PCS(dspi->cs) |
+ SPI_PUSHR_CTAS(0);
+ } else {
+ dspi->dma->tx_dma_buf[i] = SPI_PUSHR_TXDATA(val) |
+ SPI_PUSHR_PCS(dspi->cs) |
+ SPI_PUSHR_CTAS(0) |
+ SPI_PUSHR_CONT;
+ }
dspi->tx += tx_word + 1;

dma->tx_desc = dmaengine_prep_slave_single(dma->chan_tx,
--
2.10.2
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