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SubjectRe: [Patch v4 6/8] media: i2c: ov2659: Add powerdown/reset gpio handling
Hi Benoit,

On Fri, Sep 27, 2019 at 01:47:20PM -0500, Benoit Parrot wrote:
> On some board it is possible that the sensor 'powerdown' and or 'reset'
> pin might be controlled by gpio instead of being tied.
>
> To implement we add pm_runtime support which will handle the power
> up/down sequence when it is available otherwise the sensor will be
> powered on at module insertion/probe and powered off at module removal.
>
> Now originally the driver assumed that the sensor would always stay
> powered and keep its register setting. We cannot assume this anymore, so
> every time we "power up" we need to re-program the initial registers
> configuration first. This was previously done only at probe time.
>
> Signed-off-by: Benoit Parrot <bparrot@ti.com>
> ---
> drivers/media/i2c/Kconfig | 2 +-
> drivers/media/i2c/ov2659.c | 88 +++++++++++++++++++++++++++++++++++++-
> 2 files changed, 87 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
> index 7eee1812bba3..315c1d8bdb7b 100644
> --- a/drivers/media/i2c/Kconfig
> +++ b/drivers/media/i2c/Kconfig
> @@ -634,7 +634,7 @@ config VIDEO_OV2640
> config VIDEO_OV2659
> tristate "OmniVision OV2659 sensor support"
> depends on VIDEO_V4L2 && I2C
> - depends on MEDIA_CAMERA_SUPPORT
> + depends on MEDIA_CAMERA_SUPPORT && GPIOLIB
> select V4L2_FWNODE
> help
> This is a Video4Linux2 sensor driver for the OmniVision
> diff --git a/drivers/media/i2c/ov2659.c b/drivers/media/i2c/ov2659.c
> index cd4625432264..7d0baa386644 100644
> --- a/drivers/media/i2c/ov2659.c
> +++ b/drivers/media/i2c/ov2659.c
> @@ -22,9 +22,11 @@
>
> #include <linux/clk.h>
> #include <linux/delay.h>
> +#include <linux/gpio/consumer.h>
> #include <linux/i2c.h>
> #include <linux/module.h>
> #include <linux/of_graph.h>
> +#include <linux/pm_runtime.h>
>
> #include <media/i2c/ov2659.h>
> #include <media/v4l2-ctrls.h>
> @@ -218,6 +220,11 @@ struct ov2659 {
> struct sensor_register *format_ctrl_regs;
> struct ov2659_pll_ctrl pll;
> int streaming;
> + /* used to control the sensor PWDN pin */
> + struct gpio_desc *pwdn_gpio;
> + /* used to control the sensor RESETB pin */
> + struct gpio_desc *resetb_gpio;
> + int on;

Please use runtime PM for this instead. It's hard to get this right
otherwise.

Access to "on" is not serialised with the power state changes. In this case
e.g. drivers/media/i2c/ov5670.c is a good example. I think I'll see how I
could improve smiapp as well.

--
Sakari Ailus
sakari.ailus@linux.intel.com

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