| Message ID | 20240902-imx290-avail-v3-6-b32a12799fed@skidata.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | media: i2c: imx290: check for availability in probe() | expand |
Hi Benjamin On Mon, 2 Sept 2024 at 16:58, <bbara93@gmail.com> wrote: > > From: Benjamin Bara <benjamin.bara@skidata.com> > > Currently, the V4L2 subdevice is also created when the device is not > available/connected. From userspace perspective, there is no visible > difference between a working and not-working subdevice (except when > trying it out). > > This commit adds a simple availability check before starting with the > subdev initialization to error out instead. > > Signed-off-by: Benjamin Bara <benjamin.bara@skidata.com> > --- > Changes since v2: > - the new 1/8 is split out > - use dev_err_probe() (thx Laurent) > --- > drivers/media/i2c/imx290.c | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/drivers/media/i2c/imx290.c b/drivers/media/i2c/imx290.c > index 9610e9fd2059..6b292bbb0856 100644 > --- a/drivers/media/i2c/imx290.c > +++ b/drivers/media/i2c/imx290.c > @@ -1571,6 +1571,7 @@ static int imx290_probe(struct i2c_client *client) > { > struct device *dev = &client->dev; > struct imx290 *imx290; > + u64 val; > int ret; > > imx290 = devm_kzalloc(dev, sizeof(*imx290), GFP_KERNEL); > @@ -1631,6 +1632,17 @@ static int imx290_probe(struct i2c_client *client) > pm_runtime_set_autosuspend_delay(dev, 1000); > pm_runtime_use_autosuspend(dev); > > + /* Make sure the sensor is available before V4L2 subdev init. */ > + ret = cci_read(imx290->regmap, IMX290_STANDBY, &val, NULL); > + if (ret) { > + ret = dev_err_probe(dev, -ENODEV, "Failed to detect sensor\n"); > + goto err_pm; > + } > + if (val != IMX290_STANDBY_STANDBY) { As Laurent commented on v2, this is a slightly unsafe check. If the device isn't controlled via a regulator then there's no guarantee that the sensor will be in standby. The cci_read call will already have returned an error if the sensor isn't present which will be 99.999% of the error cases. If you want to catch the case where it's not in standby, why not put it into standby as a recovery mechanism. It'd be a better user experience than just bombing out of the probe. Dave > + ret = dev_err_probe(dev, -ENODEV, "Sensor is not in standby\n"); > + goto err_pm; > + } > + > /* Initialize the V4L2 subdev. */ > ret = imx290_subdev_init(imx290); > if (ret) > > -- > 2.46.0 > >
On Mon, Sep 02, 2024 at 07:22:43PM +0100, Dave Stevenson wrote: > Hi Benjamin > > On Mon, 2 Sept 2024 at 16:58, <bbara93@gmail.com> wrote: > > > > From: Benjamin Bara <benjamin.bara@skidata.com> > > > > Currently, the V4L2 subdevice is also created when the device is not > > available/connected. From userspace perspective, there is no visible > > difference between a working and not-working subdevice (except when > > trying it out). > > > > This commit adds a simple availability check before starting with the > > subdev initialization to error out instead. > > > > Signed-off-by: Benjamin Bara <benjamin.bara@skidata.com> > > --- > > Changes since v2: > > - the new 1/8 is split out > > - use dev_err_probe() (thx Laurent) > > --- > > drivers/media/i2c/imx290.c | 12 ++++++++++++ > > 1 file changed, 12 insertions(+) > > > > diff --git a/drivers/media/i2c/imx290.c b/drivers/media/i2c/imx290.c > > index 9610e9fd2059..6b292bbb0856 100644 > > --- a/drivers/media/i2c/imx290.c > > +++ b/drivers/media/i2c/imx290.c > > @@ -1571,6 +1571,7 @@ static int imx290_probe(struct i2c_client *client) > > { > > struct device *dev = &client->dev; > > struct imx290 *imx290; > > + u64 val; > > int ret; > > > > imx290 = devm_kzalloc(dev, sizeof(*imx290), GFP_KERNEL); > > @@ -1631,6 +1632,17 @@ static int imx290_probe(struct i2c_client *client) > > pm_runtime_set_autosuspend_delay(dev, 1000); > > pm_runtime_use_autosuspend(dev); > > > > + /* Make sure the sensor is available before V4L2 subdev init. */ > > + ret = cci_read(imx290->regmap, IMX290_STANDBY, &val, NULL); > > + if (ret) { > > + ret = dev_err_probe(dev, -ENODEV, "Failed to detect sensor\n"); > > + goto err_pm; > > + } > > + if (val != IMX290_STANDBY_STANDBY) { > > As Laurent commented on v2, this is a slightly unsafe check. If the > device isn't controlled via a regulator then there's no guarantee that > the sensor will be in standby. > The cci_read call will already have returned an error if the sensor > isn't present which will be 99.999% of the error cases. > > If you want to catch the case where it's not in standby, why not put > it into standby as a recovery mechanism. It'd be a better user > experience than just bombing out of the probe. I would also just drop the value check. I don't think it would really catch real world issues. > > + ret = dev_err_probe(dev, -ENODEV, "Sensor is not in standby\n"); > > + goto err_pm; > > + } > > + > > /* Initialize the V4L2 subdev. */ > > ret = imx290_subdev_init(imx290); > > if (ret)
Hi Dave! On Mon, 2 Sept 2024 at 20:22, Dave Stevenson <dave.stevenson@raspberrypi.com> wrote: > On Mon, 2 Sept 2024 at 16:58, <bbara93@gmail.com> wrote: > > > > From: Benjamin Bara <benjamin.bara@skidata.com> > > > > Currently, the V4L2 subdevice is also created when the device is not > > available/connected. From userspace perspective, there is no visible > > difference between a working and not-working subdevice (except when > > trying it out). > > > > This commit adds a simple availability check before starting with the > > subdev initialization to error out instead. > > > > Signed-off-by: Benjamin Bara <benjamin.bara@skidata.com> > > --- > > Changes since v2: > > - the new 1/8 is split out > > - use dev_err_probe() (thx Laurent) > > --- > > drivers/media/i2c/imx290.c | 12 ++++++++++++ > > 1 file changed, 12 insertions(+) > > > > diff --git a/drivers/media/i2c/imx290.c b/drivers/media/i2c/imx290.c > > index 9610e9fd2059..6b292bbb0856 100644 > > --- a/drivers/media/i2c/imx290.c > > +++ b/drivers/media/i2c/imx290.c > > @@ -1571,6 +1571,7 @@ static int imx290_probe(struct i2c_client *client) > > { > > struct device *dev = &client->dev; > > struct imx290 *imx290; > > + u64 val; > > int ret; > > > > imx290 = devm_kzalloc(dev, sizeof(*imx290), GFP_KERNEL); > > @@ -1631,6 +1632,17 @@ static int imx290_probe(struct i2c_client *client) > > pm_runtime_set_autosuspend_delay(dev, 1000); > > pm_runtime_use_autosuspend(dev); > > > > + /* Make sure the sensor is available before V4L2 subdev init. */ > > + ret = cci_read(imx290->regmap, IMX290_STANDBY, &val, NULL); > > + if (ret) { > > + ret = dev_err_probe(dev, -ENODEV, "Failed to detect sensor\n"); > > + goto err_pm; > > + } > > + if (val != IMX290_STANDBY_STANDBY) { > > As Laurent commented on v2, this is a slightly unsafe check. If the > device isn't controlled via a regulator then there's no guarantee that > the sensor will be in standby. > The cci_read call will already have returned an error if the sensor > isn't present which will be 99.999% of the error cases. > > If you want to catch the case where it's not in standby, why not put > it into standby as a recovery mechanism. It'd be a better user > experience than just bombing out of the probe. Thanks for the idea - no idea why it didn't come to my mind. I would also prefer setting STANDBY instead of reading the value. Kind regards Benjamin > Dave > > > + ret = dev_err_probe(dev, -ENODEV, "Sensor is not in standby\n"); > > + goto err_pm; > > + } > > + > > /* Initialize the V4L2 subdev. */ > > ret = imx290_subdev_init(imx290); > > if (ret) > > > > -- > > 2.46.0 > > > >
diff --git a/drivers/media/i2c/imx290.c b/drivers/media/i2c/imx290.c index 9610e9fd2059..6b292bbb0856 100644 --- a/drivers/media/i2c/imx290.c +++ b/drivers/media/i2c/imx290.c @@ -1571,6 +1571,7 @@ static int imx290_probe(struct i2c_client *client) { struct device *dev = &client->dev; struct imx290 *imx290; + u64 val; int ret; imx290 = devm_kzalloc(dev, sizeof(*imx290), GFP_KERNEL); @@ -1631,6 +1632,17 @@ static int imx290_probe(struct i2c_client *client) pm_runtime_set_autosuspend_delay(dev, 1000); pm_runtime_use_autosuspend(dev); + /* Make sure the sensor is available before V4L2 subdev init. */ + ret = cci_read(imx290->regmap, IMX290_STANDBY, &val, NULL); + if (ret) { + ret = dev_err_probe(dev, -ENODEV, "Failed to detect sensor\n"); + goto err_pm; + } + if (val != IMX290_STANDBY_STANDBY) { + ret = dev_err_probe(dev, -ENODEV, "Sensor is not in standby\n"); + goto err_pm; + } + /* Initialize the V4L2 subdev. */ ret = imx290_subdev_init(imx290); if (ret)