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    Subject[PATCH 4.14 026/164] spi: atmel: init FIFOs before spi enable
    Date
    4.14-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Eugen Hristev <eugen.hristev@microchip.com>

    commit 9581329eff9db72ab4fbb46a594fd7fdda3c51b0 upstream.

    The datasheet recommends initializing FIFOs before
    SPI enable. If we do not do it like this, there may be
    a strange behavior. We noticed that DMA does not work properly
    with FIFOs if we do not clear them beforehand or enable them
    before SPIEN.

    Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
    Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
    Signed-off-by: Mark Brown <broonie@kernel.org>
    Cc: stable@vger.kernel.org
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

    --- a/drivers/spi/spi-atmel.c
    +++ b/drivers/spi/spi-atmel.c
    @@ -1489,6 +1489,11 @@ static void atmel_spi_init(struct atmel_
    {
    spi_writel(as, CR, SPI_BIT(SWRST));
    spi_writel(as, CR, SPI_BIT(SWRST)); /* AT91SAM9263 Rev B workaround */
    +
    + /* It is recommended to enable FIFOs first thing after reset */
    + if (as->fifo_size)
    + spi_writel(as, CR, SPI_BIT(FIFOEN));
    +
    if (as->caps.has_wdrbt) {
    spi_writel(as, MR, SPI_BIT(WDRBT) | SPI_BIT(MODFDIS)
    | SPI_BIT(MSTR));
    @@ -1499,9 +1504,6 @@ static void atmel_spi_init(struct atmel_
    if (as->use_pdc)
    spi_writel(as, PTCR, SPI_BIT(RXTDIS) | SPI_BIT(TXTDIS));
    spi_writel(as, CR, SPI_BIT(SPIEN));
    -
    - if (as->fifo_size)
    - spi_writel(as, CR, SPI_BIT(FIFOEN));
    }

    static int atmel_spi_probe(struct platform_device *pdev)

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