Hi Markus,
Thank you for the patch.
On Friday 06 November 2015 14:13:43 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.
We could use a gpio hog for this, but given that the standby signal should
eventually get used, and given that specifying it in DT is a good hardware
description, that looks good to me.
> Signed-off-by: Markus Pargmann <mpa@xxxxxxxxxxxxxx>
> Reviewed-by: Philipp Zabel <p.zabel@xxxxxxxxxxxxxx>
> ---
> .../devicetree/bindings/media/i2c/mt9v032.txt | 2 ++
> drivers/media/i2c/mt9v032.c | 23 +++++++++++++++++++
> 2 files changed, 25 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..4aefde9634f5 100644
> --- a/drivers/media/i2c/mt9v032.c
> +++ b/drivers/media/i2c/mt9v032.c
> @@ -24,6 +24,7 @@
> #include <linux/videodev2.h>
> #include <linux/v4l2-mediabus.h>
> #include <linux/module.h>
> +#include <linux/gpio/consumer.h>
module.h escaped my vigilance, but let's try to keep headers alphabetically
sorted.
>
> #include <media/mt9v032.h>
> #include <media/v4l2-ctrls.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 +315,26 @@ static int mt9v032_power_on(struct mt9v032 *mt9v032)
> struct regmap *map = mt9v032->regmap;
> int ret;
>
> + gpiod_set_value_cansleep(mt9v032->reset_gpio, 1);
> +
> ret = clk_set_rate(mt9v032->clk, mt9v032->sysclk);
> if (ret < 0)
> return ret;
>
> + /* system clock has to be enabled before releasing the reset */
Nitpicking, the driver capitalizes the first letter of comments.
> ret = clk_prepare_enable(mt9v032->clk);
> if (ret)
> return ret;
>
> udelay(1);
>
> + gpiod_set_value_cansleep(mt9v032->reset_gpio, 0);
> +
> + /*
> + * After releasing reset, it can take up to 1us until the chip is done
> + */
> + udelay(1);
> +
The delay isn't necessary if there's no reset GPIO. How about
if (mt9v032->reset_gpio) {
gpiod_set_value_cansleep(mt9v032->reset_gpio, 0);
/* After releasing reset, it can take up to 1us until the
* chip is done.
*/
udelay(1);
}
And, according to the datasheet, the delay is 10 SYSCLK periods. 1µs should be
safe as the minimum SYSCLK frequency is 13 MHz. I'd still mention it in a
comment, maybe as
/* 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);
If you're fine with these changes there's no need to resubmit the patch, I can
fix it when applying it to my tree.
> /* Reset the chip and stop data read out */
> ret = regmap_write(map, MT9V032_RESET, 1);
> if (ret < 0)
> @@ -954,6 +967,16 @@ 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
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