i2c: mux: pca954x: force reset on probe if available

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 <mike.looijmans@topic.nl>
Signed-off-by: Peter Rosin <peda@axentia.se>

diff --git a/drivers/i2c/muxes/i2c-mux-pca954x.c b/drivers/i2c/muxes/i2c-mux-pca954x.c
index 09bafd3e68faf8a5bd600cb0a8fd6464443985f3..fe20b8ec52474786c87065df64127c1edc81c0cb 100644 (file)
--- 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 +390,16 @@ 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) {
+               udelay(1);
+               gpiod_set_value_cansleep(gpio, 0);
+               /* Give the chip some time to recover. */
+               udelay(1);
+       }
 
        match = of_match_device(of_match_ptr(pca954x_of_match), &client->dev);
        if (match)