diff options
Diffstat (limited to 'drivers/spi/spi-gpio.c')
| -rw-r--r-- | drivers/spi/spi-gpio.c | 16 |
1 files changed, 13 insertions, 3 deletions
diff --git a/drivers/spi/spi-gpio.c b/drivers/spi/spi-gpio.c index e7dc1fad4a87..282c5ee41a62 100644 --- a/drivers/spi/spi-gpio.c +++ b/drivers/spi/spi-gpio.c @@ -244,9 +244,19 @@ static int spi_gpio_set_direction(struct spi_device *spi, bool output) if (output) return gpiod_direction_output(spi_gpio->mosi, 1); - ret = gpiod_direction_input(spi_gpio->mosi); - if (ret) - return ret; + /* + * Only change MOSI to an input if using 3WIRE mode. + * Otherwise, MOSI could be left floating if there is + * no pull resistor connected to the I/O pin, or could + * be left logic high if there is a pull-up. Transmitting + * logic high when only clocking MISO data in can put some + * SPI devices in to a bad state. + */ + if (spi->mode & SPI_3WIRE) { + ret = gpiod_direction_input(spi_gpio->mosi); + if (ret) + return ret; + } /* * Send a turnaround high impedance cycle when switching * from output to input. Theoretically there should be |