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SubjectRe: [PATCH v4 3/3] media: ov7670: Add the s_power operation
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Hi Sakari,


On 2017/9/18 15:35, Sakari Ailus wrote:
> Hi Wenyou,
>
> Thanks for the update.
>
> The driver exposes controls that are accessible through the sub-device node
> even if the device hasn't been powered on.
>
> Many ISP and bridge drivers will also power the sensor down once the last
> user of the user space device nodes disappears. You could keep the device
> powered at all times or change the behaviour so that controls can be
> accessed when the power is off.
>
> The best option would be to convert the driver to use runtime PM.
Yes, I agree with you.
I also noticed there are a lot of things needed to improve except for
it, such as the platform data via device tree.
I would like do it in another patch set. I will continue to work on it.
> An example of this can be found in drivers/media/i2c/ov13858.c .
A good example, thank you for your providing.
>
> On Mon, Sep 18, 2017 at 02:45:14PM +0800, Wenyou Yang wrote:
>> Add the s_power operation which is responsible for manipulating the
>> power dowm mode through the PWDN pin and the reset operation through
>> the RESET pin.
>>
>> Signed-off-by: Wenyou Yang <wenyou.yang@microchip.com>
>> ---
>>
>> Changes in v4: None
>> Changes in v3: None
>> Changes in v2:
>> - Add the patch to support the get_fmt ops.
>> - Remove the redundant invoking ov7670_init_gpio().
>>
>> drivers/media/i2c/ov7670.c | 32 +++++++++++++++++++++++++++-----
>> 1 file changed, 27 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/media/i2c/ov7670.c b/drivers/media/i2c/ov7670.c
>> index 456f48057605..304abc769a67 100644
>> --- a/drivers/media/i2c/ov7670.c
>> +++ b/drivers/media/i2c/ov7670.c
>> @@ -1542,6 +1542,22 @@ static int ov7670_s_register(struct v4l2_subdev *sd, const struct v4l2_dbg_regis
>> }
>> #endif
>>
>> +static int ov7670_s_power(struct v4l2_subdev *sd, int on)
>> +{
>> + struct ov7670_info *info = to_state(sd);
>> +
>> + if (info->pwdn_gpio)
>> + gpiod_direction_output(info->pwdn_gpio, !on);
>> + if (on && info->resetb_gpio) {
>> + gpiod_set_value(info->resetb_gpio, 1);
>> + usleep_range(500, 1000);
>> + gpiod_set_value(info->resetb_gpio, 0);
>> + usleep_range(3000, 5000);
>> + }
>> +
>> + return 0;
>> +}
>> +
>> static void ov7670_get_default_format(struct v4l2_subdev *sd,
>> struct v4l2_mbus_framefmt *format)
>> {
>> @@ -1575,6 +1591,7 @@ static const struct v4l2_subdev_core_ops ov7670_core_ops = {
>> .g_register = ov7670_g_register,
>> .s_register = ov7670_s_register,
>> #endif
>> + .s_power = ov7670_s_power,
>> };
>>
>> static const struct v4l2_subdev_video_ops ov7670_video_ops = {
>> @@ -1692,23 +1709,25 @@ static int ov7670_probe(struct i2c_client *client,
>> if (ret)
>> return ret;
>>
>> - ret = ov7670_init_gpio(client, info);
>> - if (ret)
>> - goto clk_disable;
>> -
>> info->clock_speed = clk_get_rate(info->clk) / 1000000;
>> if (info->clock_speed < 10 || info->clock_speed > 48) {
>> ret = -EINVAL;
>> goto clk_disable;
>> }
>>
>> + ret = ov7670_init_gpio(client, info);
>> + if (ret)
>> + goto clk_disable;
>> +
>> + ov7670_s_power(sd, 1);
>> +
>> /* Make sure it's an ov7670 */
>> ret = ov7670_detect(sd);
>> if (ret) {
>> v4l_dbg(1, debug, client,
>> "chip found @ 0x%x (%s) is not an ov7670 chip.\n",
>> client->addr << 1, client->adapter->name);
>> - goto clk_disable;
>> + goto power_off;
>> }
>> v4l_info(client, "chip found @ 0x%02x (%s)\n",
>> client->addr << 1, client->adapter->name);
>> @@ -1787,6 +1806,8 @@ static int ov7670_probe(struct i2c_client *client,
>> #endif
>> hdl_free:
>> v4l2_ctrl_handler_free(&info->hdl);
>> +power_off:
>> + ov7670_s_power(sd, 0);
>> clk_disable:
>> clk_disable_unprepare(info->clk);
>> return ret;
>> @@ -1804,6 +1825,7 @@ static int ov7670_remove(struct i2c_client *client)
>> #if defined(CONFIG_MEDIA_CONTROLLER)
>> media_entity_cleanup(&info->sd.entity);
>> #endif
>> + ov7670_s_power(sd, 0);
>> return 0;
>> }
>>
>> --
>> 2.13.0
>>

Best Regards,
Wenyou Yang

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