Re: [PATCH v3 06/11] v4l: subdev: Make the v4l2-subdev core code enable/disable the privacy LED if present

Laurent Pinchart
2022-12-16T13:56:41Z

Hi Hans,

Thank you for the patch.

On Fri, Dec 16, 2022 at 12:30:08PM +0100, Hans de Goede wrote:
> Extend the call_s_stream() wrapper to enable/disable sensor privacy LEDs
> for sensors with a privacy LED, rather then having to duplicate this code
> in all the sensor drivers.
>
> Suggested-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
> ---
> drivers/media/v4l2-core/v4l2-subdev.c | 40 +++++++++++++++++++++++++++
> include/media/v4l2-subdev.h | 3 ++
> 2 files changed, 43 insertions(+)
>
> diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
> index 4988a25bd8f4..7344f6cd58b7 100644
> --- a/drivers/media/v4l2-core/v4l2-subdev.c
> +++ b/drivers/media/v4l2-core/v4l2-subdev.c
> @@ -318,10 +318,44 @@ static int call_get_mbus_config(struct v4l2_subdev *sd, unsigned int pad,
> sd->ops->pad->get_mbus_config(sd, pad, config);
> }
>
> +#if IS_REACHABLE(CONFIG_LEDS_CLASS)
> +#include <linux/leds.h>

Can this be moved to the top of the file ? It doesn't have to be
conditionally compiled there.

> +
> +static void call_s_stream_update_pled(struct v4l2_subdev *sd, int enable)
> +{
> + if (!sd->dev)
> + return;
> +
> + /* Try to get privacy-led once, at first s_stream() */
> + if (!sd->privacy_led)
> + sd->privacy_led = led_get(sd->dev, "privacy-led");

I'm not sure I like this much. If the LED provider isn't available
(yet), the LED will stay off. That's a privacy concern.

> +
> + if (IS_ERR(sd->privacy_led))
> + return;
> +
> + mutex_lock(&sd->privacy_led->led_access);
> +
> + if (enable) {
> + led_sysfs_disable(sd->privacy_led);
> + led_trigger_remove(sd->privacy_led);
> + led_set_brightness(sd->privacy_led, sd->privacy_led->max_brightness);
> + } else {
> + led_set_brightness(sd->privacy_led, 0);
> + led_sysfs_enable(sd->privacy_led);

I don't think you should reenable control through sysfs here. I don't
really see a use case, and you've removed the trigger anyway, so the
behaviour would be quite inconsistent.

> + }
> +
> + mutex_unlock(&sd->privacy_led->led_access);
> +}
> +#else
> +static void call_s_stream_update_pled(struct v4l2_subdev *sd, int enable) {}
> +#endif
> +
> static int call_s_stream(struct v4l2_subdev *sd, int enable)
> {
> int ret;
>
> + call_s_stream_update_pled(sd, enable);
> +
> ret = sd->ops->video->s_stream(sd, enable);
>
> if (!enable && ret < 0) {

You need to turn the LED off when enabling if .s_stream() fails.

> @@ -1050,6 +1084,11 @@ EXPORT_SYMBOL_GPL(__v4l2_subdev_init_finalize);
>
> void v4l2_subdev_cleanup(struct v4l2_subdev *sd)
> {
> +#if IS_REACHABLE(CONFIG_LEDS_CLASS)
> + if (!IS_ERR_OR_NULL(sd->privacy_led))
> + led_put(sd->privacy_led);
> +#endif
> +
> __v4l2_subdev_state_free(sd->active_state);
> sd->active_state = NULL;
> }
> @@ -1090,6 +1129,7 @@ void v4l2_subdev_init(struct v4l2_subdev *sd, const struct v4l2_subdev_ops *ops)
> sd->grp_id = 0;
> sd->dev_priv = NULL;
> sd->host_priv = NULL;
> + sd->privacy_led = NULL;
> #if defined(CONFIG_MEDIA_CONTROLLER)
> sd->entity.name = sd->name;
> sd->entity.obj_type = MEDIA_ENTITY_TYPE_V4L2_SUBDEV;
> diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
> index b15fa9930f30..0547313f98cc 100644
> --- a/include/media/v4l2-subdev.h
> +++ b/include/media/v4l2-subdev.h
> @@ -38,6 +38,7 @@ struct v4l2_subdev;
> struct v4l2_subdev_fh;
> struct tuner_setup;
> struct v4l2_mbus_frame_desc;
> +struct led_classdev;
>
> /**
> * struct v4l2_decode_vbi_line - used to decode_vbi_line
> @@ -982,6 +983,8 @@ struct v4l2_subdev {
> * appropriate functions.
> */
>
> + struct led_classdev *privacy_led;
> +
> /*
> * TODO: active_state should most likely be changed from a pointer to an
> * embedded field. For the time being it's kept as a pointer to more

--
Regards,

Laurent Pinchart