video: introduce video_set_compose_format helper

Some devices allow for downscale / upscale via the set_selection
compose API. When using it, it is necessary to perform a
set_selection of the compose target prior to setting the format.
In order to allow non-compose aware application to benefit from
it, introduce a helper which take care of setting the compose
prior to setting the format.

Signed-off-by: Alain Volmat <[email protected]>

Author: Alain Volmat

drivers/video/video_common.c

@@ -443,3 +443,24 @@ int64_t video_get_csi_link_freq(const struct device *dev, uint8_t bpp, uint8_t l
 	/* CSI D-PHY is using a DDR data bus so bitrate is twice the frequency */
 	return ctrl.val64 * bpp / (2 * lane_nb);
 }
+
+int video_set_compose_format(const struct device *dev, struct video_format *fmt)
+{
+	struct video_selection sel = {
+		.type = fmt->type,
+		.target = VIDEO_SEL_TGT_COMPOSE,
+		.rect.left = 0,
+		.rect.top = 0,
+		.rect.width = fmt->width,
+		.rect.height = fmt->height,
+	};
+	int ret;
+
+	ret = video_set_selection(dev, &sel);
+	if (ret < 0 && ret != -ENOSYS) {
+		LOG_ERR("Unable to set selection compose");
+		return ret;
+	}
+
+	return video_set_format(dev, fmt);
+}

include/zephyr/drivers/video.h

@@ -988,6 +988,22 @@ void video_closest_frmival(const struct device *dev, struct video_frmival_enum *
  */
 int64_t video_get_csi_link_freq(const struct device *dev, uint8_t bpp, uint8_t lane_nb);
 
+/**
+ * @brief Set compose rectangle (if applicable) prior to setting format
+ *
+ * Some devices expose compose capabilities, allowing them to apply a transformation
+ * (downscale / upscale) to the frame. For those devices, it is necessary to set the
+ * compose rectangle before being able to apply the frame format (which must have the
+ * same width / height and the compose rectangle width / height.
+ * In order to allow non-compose aware application to be able to control such devices,
+ * introduce a helper which, if available, will apply the compose rectangle prior to
+ * setting the format.
+ *
+ * @param dev Video device to query.
+ * @param fmt Video format structure pointer
+ */
+int video_set_compose_format(const struct device *dev, struct video_format *fmt);
+
 /**
  * @defgroup video_pixel_formats Video pixel formats
  * The '|' characters separate the pixels or logical blocks, and spaces separate the bytes.