releases/3.16.3/spi-omap2-mcspi-configure-hardware-when-slave-driver-changes-mode.patch

   1 From 97ca0d6cc118716840ea443e010cb3d5f2d25eaf Mon Sep 17 00:00:00 2001
   2 From: "Mark A. Greer" <mgreer@animalcreek.com>
   3 Date: Tue, 1 Jul 2014 20:28:32 -0700
   4 Subject: spi: omap2-mcspi: Configure hardware when slave driver changes mode
   5
   6 From: "Mark A. Greer" <mgreer@animalcreek.com>
   7
   8 commit 97ca0d6cc118716840ea443e010cb3d5f2d25eaf upstream.
   9
  10 Commit id 2bd16e3e23d9df41592c6b257c59b6860a9cc3ea
  11 (spi: omap2-mcspi: Do not configure the controller
  12 on each transfer unless needed) does its job too
  13 well so omap2_mcspi_setup_transfer() isn't called
  14 even when an SPI slave driver changes 'spi->mode'.
  15 The result is that the mode requested by the SPI
  16 slave driver never takes effect.
  17
  18 Fix this by adding the 'mode' member to the
  19 omap2_mcspi_cs structure which holds the mode
  20 value that the hardware is configured for.
  21 When the SPI slave driver changes 'spi->mode'
  22 it will be different than the value of this new
  23 member and the SPI master driver will know that
  24 the hardware must be reconfigured (by calling
  25 omap2_mcspi_setup_transfer()).
  26
  27 Fixes: 2bd16e3e23 (spi: omap2-mcspi: Do not configure the controller on each transfer unless needed)
  28 Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
  29 Signed-off-by: Mark Brown <broonie@linaro.org>
  30 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  31
  32 ---
  33  drivers/spi/spi-omap2-mcspi.c |   14 ++++++++++++++
  34  1 file changed, 14 insertions(+)
  35
  36 --- a/drivers/spi/spi-omap2-mcspi.c
  37 +++ b/drivers/spi/spi-omap2-mcspi.c
  38 @@ -149,6 +149,7 @@ struct omap2_mcspi_cs {
  39         void __iomem            *base;
  40         unsigned long           phys;
  41         int                     word_len;
  42 +       u16                     mode;
  43         struct list_head        node;
  44         /* Context save and restore shadow register */
  45         u32                     chconf0, chctrl0;
  46 @@ -926,6 +927,8 @@ static int omap2_mcspi_setup_transfer(st
  47
  48         mcspi_write_chconf0(spi, l);
  49
  50 +       cs->mode = spi->mode;
  51 +
  52         dev_dbg(&spi->dev, "setup: speed %d, sample %s edge, clk %s\n",
  53                         speed_hz,
  54                         (spi->mode & SPI_CPHA) ? "trailing" : "leading",
  55 @@ -998,6 +1001,7 @@ static int omap2_mcspi_setup(struct spi_
  56                         return -ENOMEM;
  57                 cs->base = mcspi->base + spi->chip_select * 0x14;
  58                 cs->phys = mcspi->phys + spi->chip_select * 0x14;
  59 +               cs->mode = 0;
  60                 cs->chconf0 = 0;
  61                 cs->chctrl0 = 0;
  62                 spi->controller_state = cs;
  63 @@ -1079,6 +1083,16 @@ static void omap2_mcspi_work(struct omap
  64         cs = spi->controller_state;
  65         cd = spi->controller_data;
  66
  67 +       /*
  68 +        * The slave driver could have changed spi->mode in which case
  69 +        * it will be different from cs->mode (the current hardware setup).
  70 +        * If so, set par_override (even though its not a parity issue) so
  71 +        * omap2_mcspi_setup_transfer will be called to configure the hardware
  72 +        * with the correct mode on the first iteration of the loop below.
  73 +        */
  74 +       if (spi->mode != cs->mode)
  75 +               par_override = 1;
  76 +
  77         omap2_mcspi_set_enable(spi, 0);
  78         list_for_each_entry(t, &m->transfers, transfer_list) {
  79                 if (t->tx_buf == NULL && t->rx_buf == NULL && t->len) {