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Date: Fri, 20 Sep 2019 11:55:29 -0500
From: Benoit Parrot <bparrot@...com>
To: Sakari Ailus <sakari.ailus@...ux.intel.com>
CC: Hans Verkuil <hverkuil@...all.nl>,
Prabhakar Lad <prabhakar.csengg@...il.com>,
<linux-media@...r.kernel.org>, <devicetree@...r.kernel.org>,
<linux-kernel@...r.kernel.org>
Subject: Re: [Patch v2 5/7] media: i2c: ov2659: Add powerdown/reset gpio
handling
Sakari Ailus <sakari.ailus@...ux.intel.com> wrote on Fri [2019-Sep-20 13:17:06 +0300]:
> Hi Benoit,
>
> Thanks for the update.
>
> On Thu, Sep 19, 2019 at 03:39:53PM -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.
> >
> > Now originally the driver assumed tat the sensor would always stay
> > powered and there keep its register setting. We cannot assume that 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@...com>
> > ---
> > drivers/media/i2c/Kconfig | 2 +-
> > drivers/media/i2c/ov2659.c | 88 +++++++++++++++++++++++++++++++++++++-
> > 2 files changed, 88 insertions(+), 2 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 f77320e8a60d..170f80a1a51f 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[] = {
> > @@ -1184,9 +1191,17 @@ 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 = pm_runtime_get_sync(&client->dev);
> > + if (ret < 0) {
> > + pm_runtime_put_noidle(&client->dev);
> > + goto unlock;
> > + }
> > +
> > + ov2659_init(sd, 0);
> > ov2659_set_pixel_clock(ov2659);
> > ov2659_set_frame_size(ov2659);
> > ov2659_set_format(ov2659);
> > @@ -1243,6 +1258,32 @@ static const char * const ov2659_test_pattern_menu[] = {
> > "Vertical Color Bars",
> > };
> >
> > +static int ov2659_set_power(struct ov2659 *ov2659, int on)
> > +{
> > + struct i2c_client *client = ov2659->client;
> > +
> > + dev_dbg(&client->dev, "%s: on: %d\n", __func__, on);
> > +
> > + if (on) {
> > + if (ov2659->pwdn_gpio)
> > + gpiod_direction_output(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);
> > + }
>
> Please move the code to the runtime PM callbacks.
>
> > + } else {
> > + if (ov2659->pwdn_gpio)
> > + gpiod_direction_output(ov2659->pwdn_gpio, 1);
>
> Gpiod API works with NULL GPIOs, too, so no need to check here.
Didn't realize that. I'll check.
>
> Isn't the direction supposed to be already output, so set_value would be
> more appropriate here, and above.
Oh yeah the direction should already be set.
>
> > + }
> > +
> > + ov2659->on = on;
> > +
> > + return 0;
> > +}
> > +
> > /* -----------------------------------------------------------------------------
> > * V4L2 subdev internal operations
> > */
> > @@ -1323,7 +1364,6 @@ 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);
> > }
> > }
> >
> > @@ -1400,6 +1440,18 @@ 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,
> > @@ -1445,6 +1497,9 @@ static int ov2659_probe(struct i2c_client *client)
> > ov2659->frame_size = &ov2659_framesizes[2];
> > ov2659->format_ctrl_regs = ov2659_formats[0].format_ctrl_regs;
> >
> > + pm_runtime_enable(&client->dev);
> > + pm_runtime_get_sync(&client->dev);
>
> This makes the driver depend on runtime PM.
Obviously.
Why? Is that bad?
>
> See e.g. the smiapp driver for an example how to make it work without. It
> wasn't trivial. :I You won't need autosuspend.
I took a look at that driver, but I don't get your reference to being able
to work without runtime pm!
That driver looks pretty similar to ov7740.c which I used as a reference
for this.
>
> > +
> > ret = ov2659_detect(sd);
> > if (ret < 0)
> > goto error;
> > @@ -1458,10 +1513,14 @@ static int ov2659_probe(struct i2c_client *client)
> >
> > dev_info(&client->dev, "%s sensor driver registered !!\n", sd->name);
> >
> > + pm_runtime_put(&client->dev);
> > +
> > return 0;
> >
> > error:
> > v4l2_ctrl_handler_free(&ov2659->ctrls);
> > + pm_runtime_put(&client->dev);
> > + pm_runtime_disable(&client->dev);
> > media_entity_cleanup(&sd->entity);
> > mutex_destroy(&ov2659->lock);
> > return ret;
> > @@ -1477,9 +1536,35 @@ static int ov2659_remove(struct i2c_client *client)
> > media_entity_cleanup(&sd->entity);
> > mutex_destroy(&ov2659->lock);
> >
> > + pm_runtime_disable(&client->dev);
> > +
> > return 0;
> > }
> >
> > +static int ov2659_runtime_suspend(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);
> > +
> > + ov2659_set_power(ov2659, 0);
> > +
> > + return 0;
> > +}
> > +
> > +static int ov2659_runtime_resume(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);
> > +
> > + return ov2659_set_power(ov2659, 1);
> > +}
> > +
> > +static const struct dev_pm_ops ov2659_pm_ops = {
> > + SET_RUNTIME_PM_OPS(ov2659_runtime_suspend, ov2659_runtime_resume, NULL)
> > +};
> > +
> > static const struct i2c_device_id ov2659_id[] = {
> > { "ov2659", 0 },
> > { /* sentinel */ },
> > @@ -1497,6 +1582,7 @@ 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,
>
> --
> Kind regards,
>
> Sakari Ailus
> sakari.ailus@...ux.intel.com
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