target/linux/mvebu/patches-4.14/504-spi-a3700-Change-SPI-mode-before-asserting-chip-sele.patch

   1 From dd7aa8d4b53b3484ba31ba56f3ff1be7deb38530 Mon Sep 17 00:00:00 2001
   2 From: Maxime Chevallier <maxime.chevallier@smile.fr>
   3 Date: Tue, 10 Oct 2017 10:43:18 +0200
   4 Subject: spi: a3700: Change SPI mode before asserting chip-select
   5
   6 The spi device mode should be configured in the controller before the
   7 chip-select is asserted, so that a clock polarity configuration change
   8 is not interpreted as a clock tick by the device.
   9
  10 This patch moves the mode setting to the 'prepare_message' function
  11 instead of the 'transfer_one' function.
  12
  13 By doing so, this patch also removes redundant code in
  14 a3700_spi_clock_set.
  15
  16 This was tested on EspressoBin board, with spidev.
  17
  18 Signed-off-by: Maxime Chevallier <maxime.chevallier@smile.fr>
  19 Signed-off-by: Mark Brown <broonie@kernel.org>
  20 ---
  21  drivers/spi/spi-armada-3700.c | 17 ++++-------------
  22  1 file changed, 4 insertions(+), 13 deletions(-)
  23
  24 --- a/drivers/spi/spi-armada-3700.c
  25 +++ b/drivers/spi/spi-armada-3700.c
  26 @@ -214,7 +214,7 @@ static void a3700_spi_mode_set(struct a3
  27  }
  28
  29  static void a3700_spi_clock_set(struct a3700_spi *a3700_spi,
  30 -                               unsigned int speed_hz, u16 mode)
  31 +                               unsigned int speed_hz)
  32  {
  33         u32 val;
  34         u32 prescale;
  35 @@ -239,17 +239,6 @@ static void a3700_spi_clock_set(struct a
  36                 val |= A3700_SPI_CLK_CAPT_EDGE;
  37                 spireg_write(a3700_spi, A3700_SPI_IF_TIME_REG, val);
  38         }
  39 -
  40 -       val = spireg_read(a3700_spi, A3700_SPI_IF_CFG_REG);
  41 -       val &= ~(A3700_SPI_CLK_POL | A3700_SPI_CLK_PHA);
  42 -
  43 -       if (mode & SPI_CPOL)
  44 -               val |= A3700_SPI_CLK_POL;
  45 -
  46 -       if (mode & SPI_CPHA)
  47 -               val |= A3700_SPI_CLK_PHA;
  48 -
  49 -       spireg_write(a3700_spi, A3700_SPI_IF_CFG_REG, val);
  50  }
  51
  52  static void a3700_spi_bytelen_set(struct a3700_spi *a3700_spi, unsigned int len)
  53 @@ -431,7 +420,7 @@ static void a3700_spi_transfer_setup(str
  54
  55         a3700_spi = spi_master_get_devdata(spi->master);
  56
  57 -       a3700_spi_clock_set(a3700_spi, xfer->speed_hz, spi->mode);
  58 +       a3700_spi_clock_set(a3700_spi, xfer->speed_hz);
  59
  60         byte_len = xfer->bits_per_word >> 3;
  61
  62 @@ -592,6 +581,8 @@ static int a3700_spi_prepare_message(str
  63
  64         a3700_spi_bytelen_set(a3700_spi, 4);
  65
  66 +       a3700_spi_mode_set(a3700_spi, spi->mode);
  67 +
  68         return 0;
  69  }
  70