When a sensor's fwnode references an ancillary lens or flash device (e.g. via the "lens-focus" or "flash-leds" properties), v4l2_async_create_ancillary_links() already creates a media controller link between the two entities, but their runtime PM states remain independent.
This is a problem for devices such as VCM lens actuators, which are typically spring-loaded: holding a position away from the spring's rest point requires continuous power, and the position is not retained once power is cut. If such an actuator is allowed to runtime-suspend independently of the sensor, the lens can drift back to its rest position during an otherwise active capture session. Add V4L2_SUBDEV_FL_PM_LINK to allow an ancillary subdevice to request that its runtime PM state be linked to the associated sensor. Signed-off-by: Cédric Bellegarde <[email protected]> --- Link runtime PM of ancillary devices such as lens actuators to their associated sensor, while allowing actuators to autosuspend when idle. Example usage: https://gitlab.com/gnumdk/linux/-/commit/82b2d71415a1d95b2170e19ce025afc8bbdcf145 --- drivers/media/v4l2-core/v4l2-async.c | 18 ++++++++++++++---- include/media/v4l2-subdev.h | 7 +++++++ 2 files changed, 21 insertions(+), 4 deletions(-) diff --git a/drivers/media/v4l2-core/v4l2-async.c b/drivers/media/v4l2-core/v4l2-async.c index 460bf3dbbb88..22df627153b8 100644 --- a/drivers/media/v4l2-core/v4l2-async.c +++ b/drivers/media/v4l2-core/v4l2-async.c @@ -318,6 +318,7 @@ static int v4l2_async_create_ancillary_links(struct v4l2_async_notifier *n, { #if IS_ENABLED(CONFIG_MEDIA_CONTROLLER) struct media_link *link; + struct device_link *devlink; if (sd->entity.function != MEDIA_ENT_F_LENS && sd->entity.function != MEDIA_ENT_F_FLASH) @@ -331,11 +332,20 @@ static int v4l2_async_create_ancillary_links(struct v4l2_async_notifier *n, } link = media_create_ancillary_link(&n->sd->entity, &sd->entity); - - return IS_ERR(link) ? PTR_ERR(link) : 0; -#else - return 0; + if (IS_ERR(link)) + return PTR_ERR(link); + + if (sd->flags & V4L2_SUBDEV_FL_PM_LINK) { + devlink = device_link_add(n->sd->dev, sd->dev, + DL_FLAG_PM_RUNTIME | + DL_FLAG_AUTOREMOVE_CONSUMER); + if (!devlink) + dev_warn(notifier_dev(n), + "failed to link power management of %s to %s\n", + dev_name(sd->dev), dev_name(n->sd->dev)); + } #endif + return 0; } static int v4l2_async_match_notify(struct v4l2_async_notifier *notifier, diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h index d256b7ec8f84..9f64b10afd10 100644 --- a/include/media/v4l2-subdev.h +++ b/include/media/v4l2-subdev.h @@ -972,6 +972,13 @@ struct v4l2_subdev_internal_ops { * - Multiple streams per pad are supported */ #define V4L2_SUBDEV_FL_STREAMS (1U << 4) +/* + * Set this flag to keep the subdevice active while its associated sensor is active. + * + * This is intended for ancillary devices, such as lens actuators, whose + * hardware state or physical position cannot be retained while powered off. + */ +#define V4L2_SUBDEV_FL_PM_LINK (1U << 5) struct regulator_bulk_data; --- base-commit: df2908090cda368b01ff43709f51890076c56157 change-id: 20260911-sensors_pm-787eac01aa18 Best regards, -- Cédric Bellegarde <[email protected]>
