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Subject[PATCH v3 03/10] media: i2c: imx290: fix reset GPIO pin handling
Date
According to https://www.kernel.org/doc/Documentation/gpio/consumer.txt,

- all of the gpiod_set_value_xxx() functions operate with the *logical* value.
So in imx290_power_on() the reset signal should be cleared/de-asserted with
gpiod_set_value_cansleep(imx290->rst_gpio, 0), and in imx290_power_off() the
value of 1 must be used to apply/assert the reset to the sensor. In the device
tree the reset pin is described as GPIO_ACTIVE_LOW, and gpiod_set_value_xxx()
functions take this into account,

- when devm_gpiod_get_optional() is called with GPIOD_ASIS, the GPIO is not
initialized, and the direction must be set later; using a GPIO
without setting its direction first is illegal and will result in undefined
behavior. Fix this by using GPIOD_OUT_HIGH instead of GPIOD_ASIS (this asserts
the reset signal to the sensor initially).

Signed-off-by: Andrey Konovalov <andrey.konovalov@linaro.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
---
drivers/media/i2c/imx290.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/media/i2c/imx290.c b/drivers/media/i2c/imx290.c
index d0322f9a8856..7b1de1f0c8b7 100644
--- a/drivers/media/i2c/imx290.c
+++ b/drivers/media/i2c/imx290.c
@@ -628,7 +628,7 @@ static int imx290_power_on(struct device *dev)
}

usleep_range(1, 2);
- gpiod_set_value_cansleep(imx290->rst_gpio, 1);
+ gpiod_set_value_cansleep(imx290->rst_gpio, 0);
usleep_range(30000, 31000);

return 0;
@@ -641,7 +641,7 @@ static int imx290_power_off(struct device *dev)
struct imx290 *imx290 = to_imx290(sd);

clk_disable_unprepare(imx290->xclk);
- gpiod_set_value_cansleep(imx290->rst_gpio, 0);
+ gpiod_set_value_cansleep(imx290->rst_gpio, 1);
regulator_bulk_disable(IMX290_NUM_SUPPLIES, imx290->supplies);

return 0;
@@ -757,7 +757,8 @@ static int imx290_probe(struct i2c_client *client)
goto free_err;
}

- imx290->rst_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_ASIS);
+ imx290->rst_gpio = devm_gpiod_get_optional(dev, "reset",
+ GPIOD_OUT_HIGH);
if (IS_ERR(imx290->rst_gpio)) {
dev_err(dev, "Cannot get reset gpio\n");
ret = PTR_ERR(imx290->rst_gpio);
--
2.17.1
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