Em Mon, 24 Apr 2017 17:44:02 +0300
Sakari Ailus <sakari.ailus@xxxxxx> escreveu:
> 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);
It still need to test if ret == 0, as otherwise it will do the wrong thing
here.
I guess the patch below does the trick and it is not ugly :-)
> return ret;
> }
>
> I prefer this option as it's not dependent on the system firmware type.
Thanks,
Mauro
[PATCH] ov2640: print error if devm_*_optional*() fails
devm_gpiod_get_optional() can return -ENOSYS if GPIOLIB is
disabled, causing probe to fail. Warn the user if this
happens.
Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxxx>
diff --git a/drivers/media/i2c/ov2640.c b/drivers/media/i2c/ov2640.c
index 4a2ae24f8722..8c87ed8306ea 100644
--- a/drivers/media/i2c/ov2640.c
+++ b/drivers/media/i2c/ov2640.c
@@ -765,17 +765,17 @@ static int ov2640_s_register(struct v4l2_subdev *sd,
static int ov2640_s_power(struct v4l2_subdev *sd, int on)
{
+#ifdef CONFIG_GPIOLIB
struct i2c_client *client = v4l2_get_subdevdata(sd);
struct ov2640_priv *priv = to_ov2640(client);
-#ifdef CONFIG_GPIOLIB
if (priv->pwdn_gpio)
gpiod_direction_output(priv->pwdn_gpio, !on);
if (on && priv->resetb_gpio) {
/* 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);
}
#endif
return 0;
@@ -1048,21 +1048,35 @@ 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)
dev_dbg(&client->dev, "resetb gpio is not assigned!\n");
- else if (IS_ERR(priv->resetb_gpio))
- return PTR_ERR(priv->resetb_gpio);
+
+ ret = PTR_ERR_OR_ZERO(priv->pwdn_gpio);
+ if (ret && ret != -ENOSYS) {
+ dev_dbg(&client->dev,
+ "Error %d while getting resetb gpio\n", ret);
+ return ret;
+ }
/* Request the power down GPIO asserted */
priv->pwdn_gpio = devm_gpiod_get_optional(&client->dev, "pwdn",
GPIOD_OUT_HIGH);
+
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);
+
+ ret = PTR_ERR_OR_ZERO(priv->pwdn_gpio);
+ if (ret && ret != -ENOSYS) {
+ dev_dbg(&client->dev,
+ "Error %d while getting pwdn gpio\n", ret);
+ return ret;
+ }
return 0;
}
