From 4b7d7f85abac1e7ad9e8b745694e470f0729f527 Mon Sep 17 00:00:00 2001 From: David Bauer Date: Wed, 3 Mar 2021 17:11:34 +0100 Subject: [PATCH] spi: sync up initial chipselect state When initially probing the SPI slave device, the call for disabling an SPI device without the SPI_CS_HIGH flag is not applied, as the condition for checking whether or not the state to be applied equals the one currently set evaluates to true. This however might not necessarily be the case, as the chipselect might be active. Add a force flag to spi_set_cs which allows to override this early access condition. Set it to false everywhere except when called from spi_setup to sync up the initial CS state. Fixes commit d40f0b6f2e21 ("spi: Avoid setting the chip select if we don't need to") Signed-off-by: David Bauer --- drivers/spi/spi.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -787,7 +787,7 @@ int spi_register_board_info(struct spi_b /*-------------------------------------------------------------------------*/ -static void spi_set_cs(struct spi_device *spi, bool enable) +static void spi_set_cs(struct spi_device *spi, bool enable, bool force) { bool enable1 = enable; @@ -795,7 +795,7 @@ static void spi_set_cs(struct spi_device * Avoid calling into the driver (or doing delays) if the chip select * isn't actually changing from the last time this was called. */ - if ((spi->controller->last_cs_enable == enable) && + if (!force && (spi->controller->last_cs_enable == enable) && (spi->controller->last_cs_mode_high == (spi->mode & SPI_CS_HIGH))) return; @@ -1243,7 +1243,7 @@ static int spi_transfer_one_message(stru struct spi_statistics *statm = &ctlr->statistics; struct spi_statistics *stats = &msg->spi->statistics; - spi_set_cs(msg->spi, true); + spi_set_cs(msg->spi, true, false); SPI_STATISTICS_INCREMENT_FIELD(statm, messages); SPI_STATISTICS_INCREMENT_FIELD(stats, messages); @@ -1311,9 +1311,9 @@ fallback_pio: &msg->transfers)) { keep_cs = true; } else { - spi_set_cs(msg->spi, false); + spi_set_cs(msg->spi, false, false); _spi_transfer_cs_change_delay(msg, xfer); - spi_set_cs(msg->spi, true); + spi_set_cs(msg->spi, true, false); } } @@ -1322,7 +1322,7 @@ fallback_pio: out: if (ret != 0 || !keep_cs) - spi_set_cs(msg->spi, false); + spi_set_cs(msg->spi, false, false); if (msg->status == -EINPROGRESS) msg->status = ret; @@ -3400,11 +3400,11 @@ int spi_setup(struct spi_device *spi) */ status = 0; - spi_set_cs(spi, false); + spi_set_cs(spi, false, true); pm_runtime_mark_last_busy(spi->controller->dev.parent); pm_runtime_put_autosuspend(spi->controller->dev.parent); } else { - spi_set_cs(spi, false); + spi_set_cs(spi, false, true); } mutex_unlock(&spi->controller->io_mutex);