Hi Mauro and others,
On Fri, Apr 21, 2017 at 11:39:42AM -0300, Mauro Carvalho Chehab wrote:
> Em Fri, 21 Apr 2017 08:33:12 +0200
> Pavel Machek <pavel@xxxxxx> escreveu:
>
> > Hi!
> >
> > > > Better solution would be for VIDEO_EM28XX_V4L2 to depend on GPIOLIB,
> > > > too, no? If not, should there be BUG_ON(priv->pwdn_gpio);
> > > > BUG_ON(priv->resetb_gpio);?
> > >
> > > Pavel,
> > >
> > > The em28xx driver was added upstream several years the gpio driver.
> > > It controls GPIO using a different logic. It makes no sense to make
> > > it dependent on GPIOLIB, except if someone converts it to use it.
> >
> > At least comment in the sourcecode...? Remove pwdn_gpio fields from
> > structure in !GPIOLIB case, because otherwise they are trap for the
> > programmer trying to understand what is going on?
>
>
> Sorry, I answered to another e-mail thread related to it. I assumed
> that it was c/c to linux-media, but it is, in fact a private e-mail.
I thought so, too! X-)
>
> I can see two alternatives:
>
> 1) Restore old behavior, assuming that all drivers that use OV2640 will
> have GPIOLIB enabled, with a patch like:
>
> diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
> index fd181c99ce11..4e834c36f7da 100644
> --- a/drivers/media/i2c/Kconfig
> +++ b/drivers/media/i2c/Kconfig
> @@ -521,6 +521,7 @@ config VIDEO_OV2640
> tristate "OmniVision OV2640 sensor support"
> depends on VIDEO_V4L2 && I2C
> depends on MEDIA_CAMERA_SUPPORT
> + depends on GPIOLIB if OF
> help
> This is a Video4Linux2 sensor-level driver for the OmniVision
> OV2640 camera.
>
> However, I was told that some OF drivers don't actually define the GPIO
> pins.
>
> So, the other option is:
>
> 2) Make the logic smarter for OF, with this change:
>
>
> diff --git a/drivers/media/i2c/ov2640.c b/drivers/media/i2c/ov2640.c
> index 4a2ae24f8722..8855c81a9e1f 100644
> --- a/drivers/media/i2c/ov2640.c
> +++ b/drivers/media/i2c/ov2640.c
> @@ -1048,21 +1048,39 @@ static const struct v4l2_subdev_ops ov2640_subdev_ops = {
> static int ov2640_probe_dt(struct i2c_client *client,
> struct ov2640_priv *priv)
> {
> + int ret;
> +
> /* Request the reset GPIO deasserted */
> priv->resetb_gpio = devm_gpiod_get_optional(&client->dev, "resetb",
> GPIOD_OUT_LOW);
> - if (!priv->resetb_gpio)
> + if (!priv->resetb_gpio) {
> dev_dbg(&client->dev, "resetb gpio is not assigned!\n");
> - else if (IS_ERR(priv->resetb_gpio))
> - return PTR_ERR(priv->resetb_gpio);
> + } else {
> + ret = PTR_ERR(priv->resetb_gpio);
> +
> + if (ret && ret != -ENOSYS) {
> + dev_dbg(&client->dev,
> + "Error %d while getting resetb gpio\n",
> + ret);
> + return ret;
> + }
> + }
This would work. I just wish it'd look nicer. :-)
How about something like:
ret = PTR_ERR(priv->reset_gpio);
if (!priv->reset_gpio) {
dev_dbg("reset gpio is not assigned");
} else if (ret != -ENOSYS) {
dev_dbg("error %d while getting reset gpio, ret);
return ret;
}
I prefer this option as it's not dependent on the system firmware type.
>
> /* Request the power down GPIO asserted */
> priv->pwdn_gpio = devm_gpiod_get_optional(&client->dev, "pwdn",
> GPIOD_OUT_HIGH);
> - if (!priv->pwdn_gpio)
> + if (!priv->pwdn_gpio) {
> dev_dbg(&client->dev, "pwdn gpio is not assigned!\n");
> - else if (IS_ERR(priv->pwdn_gpio))
> - return PTR_ERR(priv->pwdn_gpio);
> + } else {
> + ret = PTR_ERR(priv->pwdn_gpio);
> +
> + if (ret && ret != -ENOSYS) {
> + dev_dbg(&client->dev,
> + "Error %d while getting pwdn gpio\n",
> + ret);
> + return ret;
> + }
> + }
>
> return 0;
> }
>
> For this to work, OF caller drivers will have to depend or select GPIOLIB,
> if they need those GPIO pins.
>
> IMHO, (2) is better, but I'd like to hear more opinions from the driver
> authors that require the usage of ov2640 I2C driver.
>
> >
> > Plus, something like this, because otherwise it is quite confusing?
> >
> > Thanks,
> > Pavel
> >
> > diff --git a/drivers/media/i2c/soc_camera/ov2640.c b/drivers/media/i2c/soc_camera/ov2640.c
> > index 56de182..85620e1 100644
> > --- a/drivers/media/i2c/soc_camera/ov2640.c
> > +++ b/drivers/media/i2c/soc_camera/ov2640.c
> > @@ -1060,7 +1060,7 @@ static int ov2640_hw_reset(struct device *dev)
> > /* Active the resetb pin to perform a reset pulse */
> > gpiod_direction_output(priv->resetb_gpio, 1);
> > usleep_range(3000, 5000);
> > - gpiod_direction_output(priv->resetb_gpio, 0);
> > + gpiod_set_value(priv->resetb_gpio, 0);
> > }
> >
> > return 0;
> >
>
> That should be, IMHO, on a separate patch. Why are you changing just
> one of the set commands there? Shouldn't it be, instead:
>
> diff --git a/drivers/media/i2c/ov2640.c b/drivers/media/i2c/ov2640.c
> index 8855c81a9e1f..4ec567569ba2 100644
> --- a/drivers/media/i2c/ov2640.c
> +++ b/drivers/media/i2c/ov2640.c
> @@ -770,12 +770,12 @@ static int ov2640_s_power(struct v4l2_subdev *sd, int on)
>
> #ifdef CONFIG_GPIOLIB
> if (priv->pwdn_gpio)
> - gpiod_direction_output(priv->pwdn_gpio, !on);
> + gpiod_set_value(priv->pwdn_gpio, !on);
As long as the direction is first set somewhere... (I haven't checked.)
> if (on && priv->resetb_gpio) {
> /* Active the resetb pin to perform a reset pulse */
> - gpiod_direction_output(priv->resetb_gpio, 1);
> + gpiod_set_value(priv->resetb_gpio, 1);
> usleep_range(3000, 5000);
> - gpiod_direction_output(priv->resetb_gpio, 0);
> + gpiod_set_value(priv->resetb_gpio, 0);
> }
> #endif
--
Kind regards,
Sakari Ailus
e-mail: sakari.ailus@xxxxxx XMPP: sailus@xxxxxxxxxxxxxx
