releases/4.16.4/spi-atmel-init-fifos-before-spi-enable.patch

   1 From 9581329eff9db72ab4fbb46a594fd7fdda3c51b0 Mon Sep 17 00:00:00 2001
   2 From: Eugen Hristev <eugen.hristev@microchip.com>
   3 Date: Tue, 27 Feb 2018 12:25:07 +0200
   4 Subject: spi: atmel: init FIFOs before spi enable
   5
   6 From: Eugen Hristev <eugen.hristev@microchip.com>
   7
   8 commit 9581329eff9db72ab4fbb46a594fd7fdda3c51b0 upstream.
   9
  10 The datasheet recommends initializing FIFOs before
  11 SPI enable. If we do not do it like this, there may be
  12 a strange behavior. We noticed that DMA does not work properly
  13 with FIFOs if we do not clear them beforehand or enable them
  14 before SPIEN.
  15
  16 Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
  17 Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
  18 Signed-off-by: Mark Brown <broonie@kernel.org>
  19 Cc: stable@vger.kernel.org
  20 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  21
  22 ---
  23  drivers/spi/spi-atmel.c |    8 +++++---
  24  1 file changed, 5 insertions(+), 3 deletions(-)
  25
  26 --- a/drivers/spi/spi-atmel.c
  27 +++ b/drivers/spi/spi-atmel.c
  28 @@ -1512,6 +1512,11 @@ static void atmel_spi_init(struct atmel_
  29  {
  30         spi_writel(as, CR, SPI_BIT(SWRST));
  31         spi_writel(as, CR, SPI_BIT(SWRST)); /* AT91SAM9263 Rev B workaround */
  32 +
  33 +       /* It is recommended to enable FIFOs first thing after reset */
  34 +       if (as->fifo_size)
  35 +               spi_writel(as, CR, SPI_BIT(FIFOEN));
  36 +
  37         if (as->caps.has_wdrbt) {
  38                 spi_writel(as, MR, SPI_BIT(WDRBT) | SPI_BIT(MODFDIS)
  39                                 | SPI_BIT(MSTR));
  40 @@ -1522,9 +1527,6 @@ static void atmel_spi_init(struct atmel_
  41         if (as->use_pdc)
  42                 spi_writel(as, PTCR, SPI_BIT(RXTDIS) | SPI_BIT(TXTDIS));
  43         spi_writel(as, CR, SPI_BIT(SPIEN));
  44 -
  45 -       if (as->fifo_size)
  46 -               spi_writel(as, CR, SPI_BIT(FIFOEN));
  47  }
  48
  49  static int atmel_spi_probe(struct platform_device *pdev)