target/linux/brcm2708/patches-4.19/950-0144-spi-Make-GPIO-CSs-honour-the-SPI_NO_CS-flag.patch

   1 From d7aa9d52b7f9b2d600f9b2479767c24d438a2c68 Mon Sep 17 00:00:00 2001
   2 From: Phil Elwell <phil@raspberrypi.org>
   3 Date: Tue, 3 Jul 2018 14:23:47 +0100
   4 Subject: [PATCH] spi: Make GPIO CSs honour the SPI_NO_CS flag
   5
   6 The SPI configuration state includes an SPI_NO_CS flag that disables
   7 all CS line manipulation, for applications that want to manage their
   8 own chip selects. However, this flag is ignored by the GPIO CS code
   9 in the SPI framework.
  10
  11 Correct this omission with a trivial patch.
  12
  13 See: https://github.com/raspberrypi/linux/issues/2169
  14
  15 Signed-off-by: Phil Elwell <phil@raspberrypi.org>
  16 ---
  17  drivers/spi/spi.c | 4 +++-
  18  1 file changed, 3 insertions(+), 1 deletion(-)
  19
  20 --- a/drivers/spi/spi.c
  21 +++ b/drivers/spi/spi.c
  22 @@ -733,7 +733,9 @@ static void spi_set_cs(struct spi_device
  23                 enable = !enable;
  24
  25         if (gpio_is_valid(spi->cs_gpio)) {
  26 -               gpio_set_value_cansleep(spi->cs_gpio, !enable);
  27 +               /* Honour the SPI_NO_CS flag */
  28 +               if (!(spi->mode & SPI_NO_CS))
  29 +                       gpio_set_value_cansleep(spi->cs_gpio, !enable);
  30                 /* Some SPI masters need both GPIO CS & slave_select */
  31                 if ((spi->controller->flags & SPI_MASTER_GPIO_SS) &&
  32                     spi->controller->set_cs)