target/linux/bcm27xx/patches-5.4/950-0653-spi-Force-CS_HIGH-if-GPIO-descriptors-are-used.patch

   1 From 5f2eface651ba5da9caaa84ccca14b9202ba6202 Mon Sep 17 00:00:00 2001
   2 From: Phil Elwell <phil@raspberrypi.com>
   3 Date: Fri, 17 Apr 2020 10:46:19 +0100
   4 Subject: [PATCH] spi: Force CS_HIGH if GPIO descriptors are used
   5
   6 Commit f3186dd87669 ("spi: Optionally use GPIO descriptors for CS GPIOs")
   7 amended of_spi_parse_dt() to always set SPI_CS_HIGH for SPI slaves whose
   8 Chip Select is defined by a "cs-gpios" devicetree property.
   9
  10 This change breaks drivers whose probe functions set the mode field of
  11 the spi_device because in doing so they clear the SPI_CS_HIGH flag.
  12
  13 Fix by setting SPI_CS_HIGH in spi_setup (under the same conditions as
  14 in of_spi_parse_dt()).
  15
  16 See also: 83b2a8fe43bd ("spi: spidev: Fix CS polarity if GPIO descriptors are used")
  17
  18 Fixes: f3186dd87669 ("spi: Optionally use GPIO descriptors for CS GPIOs")
  19 Signed-off-by: Phil Elwell <phil@raspberrypi.com>
  20 ---
  21  drivers/spi/spi.c | 9 +++++++++
  22  1 file changed, 9 insertions(+)
  23
  24 --- a/drivers/spi/spi.c
  25 +++ b/drivers/spi/spi.c
  26 @@ -3034,6 +3034,7 @@ static int __spi_validate_bits_per_word(
  27   */
  28  int spi_setup(struct spi_device *spi)
  29  {
  30 +       struct spi_controller *ctlr = spi->controller;
  31         unsigned        bad_bits, ugly_bits;
  32         int             status;
  33
  34 @@ -3051,6 +3052,14 @@ int spi_setup(struct spi_device *spi)
  35                 (SPI_TX_DUAL | SPI_TX_QUAD | SPI_TX_OCTAL |
  36                  SPI_RX_DUAL | SPI_RX_QUAD | SPI_RX_OCTAL)))
  37                 return -EINVAL;
  38 +
  39 +       if (ctlr->use_gpio_descriptors && ctlr->cs_gpiods &&
  40 +           ctlr->cs_gpiods[spi->chip_select] && !(spi->mode & SPI_CS_HIGH)) {
  41 +               dev_warn(&spi->dev,
  42 +                        "setup: forcing CS_HIGH (use_gpio_descriptors)\n");
  43 +               spi->mode |= SPI_CS_HIGH;
  44 +       }
  45 +
  46         /* help drivers fail *cleanly* when they need options
  47          * that aren't supported with their current controller
  48          * SPI_CS_WORD has a fallback software implementation,