target/linux/ath79/patches-5.10/0054-spi-sync-up-initial-chipselect-state.patch

   1 From 4b7d7f85abac1e7ad9e8b745694e470f0729f527 Mon Sep 17 00:00:00 2001
   2 From: David Bauer <mail@david-bauer.net>
   3 Date: Wed, 3 Mar 2021 17:11:34 +0100
   4 Subject: [PATCH] spi: sync up initial chipselect state
   5
   6 When initially probing the SPI slave device, the call for disabling an
   7 SPI device without the SPI_CS_HIGH flag is not applied, as the
   8 condition for checking whether or not the state to be applied equals the
   9 one currently set evaluates to true.
  10
  11 This however might not necessarily be the case, as the chipselect might
  12 be active.
  13
  14 Add a force flag to spi_set_cs which allows to override this
  15 early access condition. Set it to false everywhere except when called
  16 from spi_setup to sync up the initial CS state.
  17
  18 Fixes commit d40f0b6f2e21 ("spi: Avoid setting the chip select if we don't
  19 need to")
  20
  21 Signed-off-by: David Bauer <mail@david-bauer.net>
  22 ---
  23  drivers/spi/spi.c | 16 ++++++++--------
  24  1 file changed, 8 insertions(+), 8 deletions(-)
  25
  26 --- a/drivers/spi/spi.c
  27 +++ b/drivers/spi/spi.c
  28 @@ -787,7 +787,7 @@ int spi_register_board_info(struct spi_b
  29
  30  /*-------------------------------------------------------------------------*/
  31
  32 -static void spi_set_cs(struct spi_device *spi, bool enable)
  33 +static void spi_set_cs(struct spi_device *spi, bool enable, bool force)
  34  {
  35         bool enable1 = enable;
  36
  37 @@ -795,7 +795,7 @@ static void spi_set_cs(struct spi_device
  38          * Avoid calling into the driver (or doing delays) if the chip select
  39          * isn't actually changing from the last time this was called.
  40          */
  41 -       if ((spi->controller->last_cs_enable == enable) &&
  42 +       if (!force && (spi->controller->last_cs_enable == enable) &&
  43             (spi->controller->last_cs_mode_high == (spi->mode & SPI_CS_HIGH)))
  44                 return;
  45
  46 @@ -1243,7 +1243,7 @@ static int spi_transfer_one_message(stru
  47         struct spi_statistics *statm = &ctlr->statistics;
  48         struct spi_statistics *stats = &msg->spi->statistics;
  49
  50 -       spi_set_cs(msg->spi, true);
  51 +       spi_set_cs(msg->spi, true, false);
  52
  53         SPI_STATISTICS_INCREMENT_FIELD(statm, messages);
  54         SPI_STATISTICS_INCREMENT_FIELD(stats, messages);
  55 @@ -1311,9 +1311,9 @@ fallback_pio:
  56                                          &msg->transfers)) {
  57                                 keep_cs = true;
  58                         } else {
  59 -                               spi_set_cs(msg->spi, false);
  60 +                               spi_set_cs(msg->spi, false, false);
  61                                 _spi_transfer_cs_change_delay(msg, xfer);
  62 -                               spi_set_cs(msg->spi, true);
  63 +                               spi_set_cs(msg->spi, true, false);
  64                         }
  65                 }
  66
  67 @@ -1322,7 +1322,7 @@ fallback_pio:
  68
  69  out:
  70         if (ret != 0 || !keep_cs)
  71 -               spi_set_cs(msg->spi, false);
  72 +               spi_set_cs(msg->spi, false, false);
  73
  74         if (msg->status == -EINPROGRESS)
  75                 msg->status = ret;
  76 @@ -3400,11 +3400,11 @@ int spi_setup(struct spi_device *spi)
  77                  */
  78                 status = 0;
  79
  80 -               spi_set_cs(spi, false);
  81 +               spi_set_cs(spi, false, true);
  82                 pm_runtime_mark_last_busy(spi->controller->dev.parent);
  83                 pm_runtime_put_autosuspend(spi->controller->dev.parent);
  84         } else {
  85 -               spi_set_cs(spi, false);
  86 +               spi_set_cs(spi, false, true);
  87         }
  88
  89         mutex_unlock(&spi->controller->io_mutex);