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drivers: video: Add get_volatile_ctrl driver's API

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Add get_volatile_ctrl() driver's API to retrieve the current value of a
control marked as volatile, e.g. gain, exposure. This function triggers
a hardware register reading instead of returning a cached value to ensure
that users always get a fresh value which is constantly updated by the HW.

Note that the driver is responsible for marking a control as volatile by
setting VIDEO_CTRL_FLAG_VOLATILE when registering a control because not
all hardwares work the same way for the same control.

Signed-off-by: Phi Bang Nguyen <phibang.nguyen@nxp.com>
This commit is contained in:
Phi Bang Nguyen 2025-03-28 23:37:52 +01:00 • committed by Benjamin Cabé
commit cbf104f3d0
2 changed files with 17 additions and 5 deletions
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11
drivers/video/video_ctrls.c
View file

@ -151,6 +151,17 @@ int video_get_ctrl(const struct device *dev, struct video_control *control)
return -EACCES;
}
if (ctrl->flags & VIDEO_CTRL_FLAG_VOLATILE) {
if (DEVICE_API_GET(video, ctrl->vdev->dev)->get_volatile_ctrl == NULL) {
return -ENOSYS;
}
/* Call driver's get_volatile_ctrl */
return DEVICE_API_GET(video, ctrl->vdev->dev)
->get_volatile_ctrl(ctrl->vdev->dev, control);
}
/* Read control value in cache memory */
if (ctrl->type == VIDEO_CTRL_TYPE_INTEGER64) {
control->val64 = ctrl->val64;
} else {

11
include/zephyr/drivers/video.h
View file

@ -318,12 +318,12 @@ typedef int (*video_api_flush_t)(const struct device *dev, enum video_endpoint_i
typedef int (*video_api_set_stream_t)(const struct device *dev, bool enable);
/**
* @typedef video_api_set_ctrl_t
* @brief Set a video control value.
* @typedef video_api_ctrl_t
* @brief Set/Get a video control value.
*
* See video_set_ctrl() for argument descriptions.
* See video_set_ctrl() or video_get_ctrl() for argument descriptions.
*/
typedef int (*video_api_set_ctrl_t)(const struct device *dev, struct video_control *ctrl);
typedef int (*video_api_ctrl_t)(const struct device *dev, struct video_control *ctrl);
/**
* @typedef video_api_get_caps_t
@ -353,7 +353,8 @@ __subsystem struct video_driver_api {
video_api_enqueue_t enqueue;
video_api_dequeue_t dequeue;
video_api_flush_t flush;
video_api_set_ctrl_t set_ctrl;
video_api_ctrl_t set_ctrl;
video_api_ctrl_t get_volatile_ctrl;
video_api_set_signal_t set_signal;
video_api_set_frmival_t set_frmival;
video_api_get_frmival_t get_frmival;