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From:   "Lad, Prabhakar" <prabhakar.csengg@gmail.com>
Date:   Fri, 27 Sep 2019 22:09:45 +0100
Message-ID: <CA+V-a8vdjYoVxScjBAt5fb-sPWjsj53R8JpEfWt4Dvd5Kcr_0Q@mail.gmail.com>
Subject: Re: [Patch v4 6/8] media: i2c: ov2659: Add powerdown/reset gpio handling
To:     Benoit Parrot <bparrot@ti.com>
Cc:     Hans Verkuil <hverkuil@xs4all.nl>,
        Sakari Ailus <sakari.ailus@linux.intel.com>,
        linux-media <linux-media@vger.kernel.org>,
        devicetree@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>
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Sender: linux-kernel-owner@vger.kernel.org
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Hi Benoit,

thank you for the patch.

On Fri, Sep 27, 2019 at 7:49 PM Benoit Parrot <bparrot@ti.com> 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;
>  };
>
>  static const struct sensor_register ov2659_init_regs[] = {
> @@ -1184,10 +1191,19 @@ static int ov2659_s_stream(struct v4l2_subdev *sd, int on)
>                 /* Stop Streaming Sequence */
>                 ov2659_set_streaming(ov2659, 0);
>                 ov2659->streaming = on;
> +               pm_runtime_put(&client->dev);
>                 goto unlock;
>         }
>
> -       ret = ov2659_set_pixel_clock(ov2659);
> +       ret = pm_runtime_get_sync(&client->dev);
> +       if (ret < 0) {
> +               pm_runtime_put_noidle(&client->dev);
> +               goto unlock;
> +       }
> +
> +       ret = ov2659_init(sd, 0);
> +       if (!ret)
> +               ret = ov2659_set_pixel_clock(ov2659);
>         if (!ret)
>                 ret = ov2659_set_frame_size(ov2659);
>         if (!ret)
> @@ -1229,6 +1245,9 @@ static int ov2659_s_ctrl(struct v4l2_ctrl *ctrl)
>         struct ov2659 *ov2659 =
>                         container_of(ctrl->handler, struct ov2659, ctrls);
>
> +       if (!ov2659->on)
> +               return 0;
> +
why is this check only in s_ctrl() ? I think we could just drop this variable.

Cheers,
--Prabhakar

>         switch (ctrl->id) {
>         case V4L2_CID_TEST_PATTERN:
>                 return ov2659_set_test_pattern(ov2659, ctrl->val);
> @@ -1246,6 +1265,43 @@ static const char * const ov2659_test_pattern_menu[] = {
>         "Vertical Color Bars",
>  };
>
> +static int ov2659_power_off(struct device *dev)
> +{
> +       struct i2c_client *client = to_i2c_client(dev);
> +       struct v4l2_subdev *sd = i2c_get_clientdata(client);
> +       struct ov2659 *ov2659 = to_ov2659(sd);
> +
> +       dev_dbg(&client->dev, "%s:\n", __func__);
> +
> +       gpiod_set_value(ov2659->pwdn_gpio, 1);
> +
> +       ov2659->on = false;
> +
> +       return 0;
> +}
> +
> +static int ov2659_power_on(struct device *dev)
> +{
> +       struct i2c_client *client = to_i2c_client(dev);
> +       struct v4l2_subdev *sd = i2c_get_clientdata(client);
> +       struct ov2659 *ov2659 = to_ov2659(sd);
> +
> +       dev_dbg(&client->dev, "%s:\n", __func__);
> +
> +       gpiod_set_value(ov2659->pwdn_gpio, 0);
> +
> +       if (ov2659->resetb_gpio) {
> +               gpiod_set_value(ov2659->resetb_gpio, 1);
> +               usleep_range(500, 1000);
> +               gpiod_set_value(ov2659->resetb_gpio, 0);
> +               usleep_range(3000, 5000);
> +       }
> +
> +       ov2659->on = true;
> +
> +       return 0;
> +}
> +
>  /* -----------------------------------------------------------------------------
>   * V4L2 subdev internal operations
>   */
> @@ -1326,7 +1382,6 @@ static int ov2659_detect(struct v4l2_subdev *sd)
>                         ret = -ENODEV;
>                 } else {
>                         dev_info(&client->dev, "Found OV%04X sensor\n", id);
> -                       ret = ov2659_init(sd, 0);
>                 }
>         }
>
> @@ -1403,6 +1458,18 @@ static int ov2659_probe(struct i2c_client *client)
>             ov2659->xvclk_frequency > 27000000)
>                 return -EINVAL;
>
> +       /* Optional gpio don't fail if not present */
> +       ov2659->pwdn_gpio = devm_gpiod_get_optional(&client->dev, "powerdown",
> +                                                   GPIOD_OUT_LOW);
> +       if (IS_ERR(ov2659->pwdn_gpio))
> +               return PTR_ERR(ov2659->pwdn_gpio);
> +
> +       /* Optional gpio don't fail if not present */
> +       ov2659->resetb_gpio = devm_gpiod_get_optional(&client->dev, "reset",
> +                                                     GPIOD_OUT_HIGH);
> +       if (IS_ERR(ov2659->resetb_gpio))
> +               return PTR_ERR(ov2659->resetb_gpio);
> +
>         v4l2_ctrl_handler_init(&ov2659->ctrls, 2);
>         ov2659->link_frequency =
>                         v4l2_ctrl_new_std(&ov2659->ctrls, &ov2659_ctrl_ops,
> @@ -1448,6 +1515,8 @@ static int ov2659_probe(struct i2c_client *client)
>         ov2659->frame_size = &ov2659_framesizes[2];
>         ov2659->format_ctrl_regs = ov2659_formats[0].format_ctrl_regs;
>
> +       ov2659_power_on(&client->dev);
> +
>         ret = ov2659_detect(sd);
>         if (ret < 0)
>                 goto error;
> @@ -1461,10 +1530,15 @@ static int ov2659_probe(struct i2c_client *client)
>
>         dev_info(&client->dev, "%s sensor driver registered !!\n", sd->name);
>
> +       pm_runtime_set_active(&client->dev);
> +       pm_runtime_enable(&client->dev);
> +       pm_runtime_idle(&client->dev);
> +
>         return 0;
>
>  error:
>         v4l2_ctrl_handler_free(&ov2659->ctrls);
> +       ov2659_power_off(&client->dev);
>         media_entity_cleanup(&sd->entity);
>         mutex_destroy(&ov2659->lock);
>         return ret;
> @@ -1480,9 +1554,18 @@ static int ov2659_remove(struct i2c_client *client)
>         media_entity_cleanup(&sd->entity);
>         mutex_destroy(&ov2659->lock);
>
> +       pm_runtime_disable(&client->dev);
> +       if (!pm_runtime_status_suspended(&client->dev))
> +               ov2659_power_off(&client->dev);
> +       pm_runtime_set_suspended(&client->dev);
> +
>         return 0;
>  }
>
> +static const struct dev_pm_ops ov2659_pm_ops = {
> +       SET_RUNTIME_PM_OPS(ov2659_power_off, ov2659_power_on, NULL)
> +};
> +
>  static const struct i2c_device_id ov2659_id[] = {
>         { "ov2659", 0 },
>         { /* sentinel */ },
> @@ -1500,6 +1583,7 @@ MODULE_DEVICE_TABLE(of, ov2659_of_match);
>  static struct i2c_driver ov2659_i2c_driver = {
>         .driver = {
>                 .name   = DRIVER_NAME,
> +               .pm     = &ov2659_pm_ops,
>                 .of_match_table = of_match_ptr(ov2659_of_match),
>         },
>         .probe_new      = ov2659_probe,
> --
> 2.17.1
>