Re: [PATCH v2 1/3] [media] mt9v032: Add reset and standby gpios

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Markus,

Thank you for the patch.

On Monday 14 December 2015 15:41:51 Markus Pargmann wrote:
> Add optional reset and standby gpios. The reset gpio is used to reset
> the chip in power_on().
> 
> The standby gpio is not used currently. It is just unset, so the chip is
> not in standby.
> 
> Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
> Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
> Acked-by: Rob Herring <robh@kernel.org>
> ---
>  .../devicetree/bindings/media/i2c/mt9v032.txt      |  2 ++
>  drivers/media/i2c/mt9v032.c                        | 28 +++++++++++++++++++
>  2 files changed, 30 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/media/i2c/mt9v032.txt
> b/Documentation/devicetree/bindings/media/i2c/mt9v032.txt index
> 202565313e82..100f0ae43269 100644
> --- a/Documentation/devicetree/bindings/media/i2c/mt9v032.txt
> +++ b/Documentation/devicetree/bindings/media/i2c/mt9v032.txt
> @@ -20,6 +20,8 @@ Optional Properties:
> 
>  - link-frequencies: List of allowed link frequencies in Hz. Each frequency
> is expressed as a 64-bit big-endian integer.
> +- reset-gpios: GPIO handle which is connected to the reset pin of the chip.
> +- standby-gpios: GPIO handle which is connected to the standby pin of the
> chip.
> 
>  For further reading on port node refer to
>  Documentation/devicetree/bindings/media/video-interfaces.txt.
> diff --git a/drivers/media/i2c/mt9v032.c b/drivers/media/i2c/mt9v032.c
> index a68ce94ee097..c1bc564a0979 100644
> --- a/drivers/media/i2c/mt9v032.c
> +++ b/drivers/media/i2c/mt9v032.c
> @@ -14,6 +14,7 @@
> 
>  #include <linux/clk.h>
>  #include <linux/delay.h>
> +#include <linux/gpio/consumer.h>
>  #include <linux/i2c.h>
>  #include <linux/log2.h>
>  #include <linux/mutex.h>
> @@ -251,6 +252,8 @@ struct mt9v032 {
> 
>  	struct regmap *regmap;
>  	struct clk *clk;
> +	struct gpio_desc *reset_gpio;
> +	struct gpio_desc *standby_gpio;
> 
>  	struct mt9v032_platform_data *pdata;
>  	const struct mt9v032_model_info *model;
> @@ -312,16 +315,31 @@ static int mt9v032_power_on(struct mt9v032 *mt9v032)
>  	struct regmap *map = mt9v032->regmap;
>  	int ret;
> 
> +	if (mt9v032->reset_gpio)
> +		gpiod_set_value_cansleep(mt9v032->reset_gpio, 1);
> +

gpiod_set_value_cansleep() already checks whether the gpiod is NULL, you don't 
need to duplicate the check here.

Apart from that,

Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

No need to resubmit I'll fix this when applying.

>  	ret = clk_set_rate(mt9v032->clk, mt9v032->sysclk);
>  	if (ret < 0)
>  		return ret;
> 
> +	/* System clock has to be enabled before releasing the reset */
>  	ret = clk_prepare_enable(mt9v032->clk);
>  	if (ret)
>  		return ret;
> 
>  	udelay(1);
> 
> +	if (mt9v032->reset_gpio) {
> +		gpiod_set_value_cansleep(mt9v032->reset_gpio, 0);
> +
> +		/* After releasing reset we need to wait 10 clock cycles
> +		 * before accessing the sensor over I2C. As the minimum SYSCLK
> +		 * frequency is 13MHz, waiting 1µs will be enough in the worst
> +		 * case.
> +		 */
> +		udelay(1);
> +	}
> +
>  	/* Reset the chip and stop data read out */
>  	ret = regmap_write(map, MT9V032_RESET, 1);
>  	if (ret < 0)
> @@ -954,6 +972,16 @@ static int mt9v032_probe(struct i2c_client *client,
>  	if (IS_ERR(mt9v032->clk))
>  		return PTR_ERR(mt9v032->clk);
> 
> +	mt9v032->reset_gpio = devm_gpiod_get_optional(&client->dev, "reset",
> +						      GPIOD_OUT_HIGH);
> +	if (IS_ERR(mt9v032->reset_gpio))
> +		return PTR_ERR(mt9v032->reset_gpio);
> +
> +	mt9v032->standby_gpio = devm_gpiod_get_optional(&client->dev, "standby",
> +							GPIOD_OUT_LOW);
> +	if (IS_ERR(mt9v032->standby_gpio))
> +		return PTR_ERR(mt9v032->standby_gpio);
> +
>  	mutex_init(&mt9v032->power_lock);
>  	mt9v032->pdata = pdata;
>  	mt9v032->model = (const void *)did->driver_data;

-- 
Regards,

Laurent Pinchart