linux-kernel - [PATCH v4 03/10] media: i2c: imx290: fix reset GPIO pin handling

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Message-Id: <20200607163025.8409-4-andrey.konovalov@linaro.org>
Date:   Sun,  7 Jun 2020 19:30:18 +0300
From:   Andrey Konovalov <andrey.konovalov@...aro.org>
To:     mchehab@...nel.org, sakari.ailus@....fi,
        manivannan.sadhasivam@...aro.org
Cc:     linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        c.barrett@...mos.com, a.brela@...mos.com, peter.griffin@...aro.org,
        Andrey Konovalov <andrey.konovalov@...aro.org>
Subject: [PATCH v4 03/10] media: i2c: imx290: fix reset GPIO pin handling

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@...aro.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.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