spi: atmel: init FIFOs before spi enable
authorEugen Hristev <eugen.hristev@microchip.com>
Tue, 27 Feb 2018 10:25:07 +0000 (12:25 +0200)
committerMark Brown <broonie@kernel.org>
Tue, 27 Feb 2018 14:00:45 +0000 (14:00 +0000)
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
drivers/spi/spi-atmel.c

index 4a11fc0d41367c2dd92a0559f041cd24795ae5fb..b7936f81537358dacb51a417801f5e0dac28b457 100644 (file)
@@ -1512,6 +1512,11 @@ 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 */
 {
        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));
        if (as->caps.has_wdrbt) {
                spi_writel(as, MR, SPI_BIT(WDRBT) | SPI_BIT(MODFDIS)
                                | SPI_BIT(MSTR));
@@ -1522,9 +1527,6 @@ 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->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)
 }
 
 static int atmel_spi_probe(struct platform_device *pdev)