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Date: Mon, 18 Sep 2017 17:26:16 +0800 From: "Yang, Wenyou" <Wenyou.Yang@...rochip.com> To: Sakari Ailus <sakari.ailus@....fi> CC: Jonathan Corbet <corbet@....net>, Nicolas Ferre <nicolas.ferre@...rochip.com>, <linux-kernel@...r.kernel.org>, <linux-arm-kernel@...ts.infradead.org>, Linux Media Mailing List <linux-media@...r.kernel.org>, Mauro Carvalho Chehab <mchehab@...pensource.com> Subject: Re: [PATCH v4 3/3] media: ov7670: Add the s_power operation 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@...rochip.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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