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@xxxxxxxx>
---
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
