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Subject[PATCH] spi: atmel: init FIFOs before spi enable
Date
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>
---
drivers/spi/spi-atmel.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/spi/spi-atmel.c b/drivers/spi/spi-atmel.c
index 6694709..0478758 100644
--- a/drivers/spi/spi-atmel.c
+++ b/drivers/spi/spi-atmel.c
@@ -1489,6 +1489,11 @@ static void atmel_spi_init(struct atmel_spi *as)
{
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_spi *as)
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)
--
2.7.4
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