Instead of just hogging the reset GPIO into deactivated state, activate and then de-activate the reset. This allows for better recovery if the CPU was reset halfway through an I2C transaction for example.
Signed-off-by: Mike Looijmans <[email protected]> --- drivers/i2c/muxes/i2c-mux-pca954x.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/drivers/i2c/muxes/i2c-mux-pca954x.c b/drivers/i2c/muxes/i2c-mux-pca954x.c index 09bafd3..13e10d0 100644 --- a/drivers/i2c/muxes/i2c-mux-pca954x.c +++ b/drivers/i2c/muxes/i2c-mux-pca954x.c @@ -36,6 +36,7 @@ */ #include <linux/device.h> +#include <linux/delay.h> #include <linux/gpio/consumer.h> #include <linux/i2c.h> #include <linux/i2c-mux.h> @@ -389,10 +390,17 @@ static int pca954x_probe(struct i2c_client *client, i2c_set_clientdata(client, muxc); data->client = client; - /* Get the mux out of reset if a reset GPIO is specified. */ - gpio = devm_gpiod_get_optional(&client->dev, "reset", GPIOD_OUT_LOW); + /* Reset the mux if a reset GPIO is specified. */ + gpio = devm_gpiod_get_optional(&client->dev, "reset", GPIOD_OUT_HIGH); if (IS_ERR(gpio)) return PTR_ERR(gpio); + if (gpio) { + /* Datasheet specifies a 4 ns reset-low time */ + udelay(1); + gpiod_set_value_cansleep(gpio, 0); + /* Datasheet specifies a 500 ns reset recovery time */ + udelay(1); + } match = of_match_device(of_match_ptr(pca954x_of_match), &client->dev); if (match) -- 1.9.1
