drivers: video: Introduce video_mdev structure

ngphibang · ngphibang · commit 950e7306fa5c · 2025-04-21T21:09:42.000+02:00
The video_mdev structure is used to determine a video device, usually a
DMA or ISP device, as a main device of the video pipeline it belongs to.
The main video device represents the whole pipeline to communicate with
the application.

The video subsystem expose the list of main video devices to userspace
via two APIs:

- video_get_dev() : get a video device by index
- video_get_devs_num() : get the number of registered video devices

With this, we don't need to define a zephyr,camera chosen node anymore.
Moreover, application can switch between multiple video devices/pipelines
and not restricted to a single pre-defined camera node.

Signed-off-by: Phi Bang Nguyen &lt;phibang.nguyen@nxp.com&gt;
diff --git a/boards/arduino/nicla_vision/arduino_nicla_vision_stm32h747xx_m7.dts b/boards/arduino/nicla_vision/arduino_nicla_vision_stm32h747xx_m7.dts
@@ -22,7 +22,6 @@
 		zephyr,sram = &sram0;
 		zephyr,flash = &flash0;
 		zephyr,code-partition = &slot0_partition;
-		zephyr,camera = &dcmi;
 	};
 
 	aliases {
diff --git a/boards/espressif/esp32s3_eye/esp32s3_eye_procpu.dts b/boards/espressif/esp32s3_eye/esp32s3_eye_procpu.dts
@@ -31,7 +31,6 @@
 		zephyr,code-partition = &slot0_partition;
 		zephyr,bt-hci = &esp32_bt_hci;
 		zephyr,display = &st7789v;
-		zephyr,camera = &lcd_cam;
 	};
 
 	buttons {
diff --git a/boards/seeed/xiao_esp32s3/xiao_esp32s3_procpu_sense.dts b/boards/seeed/xiao_esp32s3/xiao_esp32s3_procpu_sense.dts
@@ -11,10 +11,6 @@
 / {
 	model = "Seeed Xiao ESP32S3 PROCPU Sense";
 	compatible = "seeed,xiao-esp32s3";
-
-	chosen {
-		zephyr,camera = &lcd_cam;
-	};
 };
 
 &i2c1 {
diff --git a/boards/shields/dvp_fpc24_mt9m114/dvp_fpc24_mt9m114.overlay b/boards/shields/dvp_fpc24_mt9m114/dvp_fpc24_mt9m114.overlay
@@ -4,12 +4,6 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-/{
-	chosen {
-		zephyr,camera = &dvp_fpc24_interface;
-	};
-};
-
 &dvp_fpc24_i2c {
 	mt9m114: mt9m114@48 {
 		compatible = "aptina,mt9m114";
diff --git a/boards/shields/nxp_btb44_ov5640/nxp_btb44_ov5640.overlay b/boards/shields/nxp_btb44_ov5640/nxp_btb44_ov5640.overlay
@@ -6,12 +6,6 @@
 
 #include <zephyr/dt-bindings/video/video-interfaces.h>
 
-/{
-	chosen {
-		zephyr,camera = &nxp_csi;
-	};
-};
-
 &nxp_cam_i2c {
 	status = "okay";
 
diff --git a/boards/shields/st_b_cams_omv_mb1683/st_b_cams_omv_mb1683.overlay b/boards/shields/st_b_cams_omv_mb1683/st_b_cams_omv_mb1683.overlay
@@ -7,12 +7,6 @@
 
 #include <zephyr/dt-bindings/video/video-interfaces.h>
 
-/ {
-	chosen {
-		zephyr,camera = &st_cam_dvp;
-	};
-};
-
 &st_cam_i2c {
 
 	ov5640: ov5640@3c {
diff --git a/boards/shields/weact_ov2640_cam_module/weact_ov2640_cam_module.overlay b/boards/shields/weact_ov2640_cam_module/weact_ov2640_cam_module.overlay
@@ -4,12 +4,6 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-/ {
-	chosen {
-		zephyr,camera = &zephyr_camera_dvp;
-	};
-};
-
 &zephyr_camera_i2c {
 	status = "okay";
 	clock-frequency = <I2C_BITRATE_FAST>;
diff --git a/cmake/linker_script/common/common-ram.cmake b/cmake/linker_script/common/common-ram.cmake
@@ -127,6 +127,7 @@ endif()
 
 if(CONFIG_VIDEO)
   zephyr_iterable_section(NAME video_device GROUP DATA_REGION ${XIP_ALIGN_WITH_INPUT} SUBALIGN ${CONFIG_LINKER_ITERABLE_SUBALIGN})
+  zephyr_iterable_section(NAME video_mdev GROUP DATA_REGION ${XIP_ALIGN_WITH_INPUT} SUBALIGN ${CONFIG_LINKER_ITERABLE_SUBALIGN})
 endif()
 
 if(CONFIG_LOG)
diff --git a/drivers/video/video.ld b/drivers/video/video.ld
@@ -1,3 +1,4 @@
 #include <zephyr/linker/iterable_sections.h>
 
 ITERABLE_SECTION_RAM(video_device, Z_LINK_ITERABLE_SUBALIGN)
+ITERABLE_SECTION_RAM(video_mdev, Z_LINK_ITERABLE_SUBALIGN)
diff --git a/drivers/video/video_device.c b/drivers/video/video_device.c
@@ -4,6 +4,8 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
+#include <zephyr/drivers/video.h>
+
 #include "video_device.h"
 
 struct video_device *video_find_vdev(const struct device *dev)
@@ -20,3 +22,21 @@ struct video_device *video_find_vdev(const struct device *dev)
 
 	return NULL;
 }
+
+const struct device *video_get_dev(uint8_t i)
+{
+	const struct video_mdev *vmd = NULL;
+
+	STRUCT_SECTION_GET(video_mdev, i, &vmd);
+
+	return vmd->dev;
+}
+
+uint8_t video_get_devs_num(void)
+{
+	uint8_t count = 0;
+
+	STRUCT_SECTION_COUNT(video_mdev, &count);
+
+	return count;
+}
diff --git a/drivers/video/video_device.h b/drivers/video/video_device.h
@@ -16,13 +16,22 @@ struct video_device {
 	sys_dlist_t ctrls;
 };
 
+struct video_mdev {
+	const struct device *dev;
+};
+
 #define VIDEO_DEVICE_DEFINE(name, device, source)                                                  \
 	static STRUCT_SECTION_ITERABLE(video_device, name) = {                                     \
 		.dev = device,                                                                     \
 		.src_dev = source,                                                                 \
 		.ctrls = SYS_DLIST_STATIC_INIT(&name.ctrls),                                       \
 	}
 
+#define VIDEO_MDEV_DEFINE(name, device)                                                            \
+	static STRUCT_SECTION_ITERABLE(video_mdev, name_##mdev) = {                                \
+		.dev = device,                                                                     \
+	}
+
 struct video_device *video_find_vdev(const struct device *dev);
 
 #endif /* ZEPHYR_INCLUDE_DRIVERS_VIDEO_VIDEO_DEVICE_H_ */
diff --git a/drivers/video/video_emul_rx.c b/drivers/video/video_emul_rx.c
@@ -282,6 +282,8 @@ int emul_rx_init(const struct device *dev)
 	DEVICE_DT_INST_DEFINE(n, &emul_rx_init, NULL, &emul_rx_data_##n, &emul_rx_cfg_##n,         \
 			      POST_KERNEL, CONFIG_VIDEO_INIT_PRIORITY, &emul_rx_driver_api);       \
                                                                                                    \
-	VIDEO_DEVICE_DEFINE(emul_rx_##n, DEVICE_DT_INST_GET(n), emul_rx_cfg_##n.source_dev);
+	VIDEO_DEVICE_DEFINE(emul_rx_##n, DEVICE_DT_INST_GET(n), emul_rx_cfg_##n.source_dev);       \
+                                                                                                   \
+	VIDEO_MDEV_DEFINE(emul_rx_##n, DEVICE_DT_INST_GET(n));
 
 DT_INST_FOREACH_STATUS_OKAY(EMUL_RX_DEFINE)
diff --git a/drivers/video/video_esp32_dvp.c b/drivers/video/video_esp32_dvp.c
@@ -452,6 +452,8 @@ DEVICE_DT_INST_DEFINE(0, video_esp32_init, NULL, &esp32_data, &esp32_config, POS
 
 VIDEO_DEVICE_DEFINE(esp32, DEVICE_DT_INST_GET(0), esp32_config.source_dev);
 
+VIDEO_MDEV_DEFINE(esp32, DEVICE_DT_INST_GET(0));
+
 static int video_esp32_cam_init_master_clock(void)
 {
 	int ret = 0;
diff --git a/drivers/video/video_mcux_csi.c b/drivers/video/video_mcux_csi.c
@@ -483,4 +483,6 @@ DEVICE_DT_INST_DEFINE(0, &video_mcux_csi_init_0, NULL, &video_mcux_csi_data_0,
 
 VIDEO_DEVICE_DEFINE(csi, DEVICE_DT_INST_GET(0), video_mcux_csi_config_0.source_dev);
 
+VIDEO_MDEV_DEFINE(csi, DEVICE_DT_INST_GET(0));
+
 #endif
diff --git a/drivers/video/video_mcux_smartdma.c b/drivers/video/video_mcux_smartdma.c
@@ -383,6 +383,8 @@ static DEVICE_API(video, nxp_video_sdma_api) = {
 			      &sdma_config_##inst, POST_KERNEL,                                    \
 			      CONFIG_KERNEL_INIT_PRIORITY_DEVICE, &nxp_video_sdma_api);            \
                                                                                                    \
-	VIDEO_DEVICE_DEFINE(sdma_##inst, DEVICE_DT_INST_GET(inst), sdma_config_##inst.sensor_dev);
+	VIDEO_DEVICE_DEFINE(sdma_##inst, DEVICE_DT_INST_GET(inst), sdma_config_##inst.sensor_dev); \
+                                                                                                   \
+	VIDEO_MDEV_DEFINE(sdma_##inst, DEVICE_DT_INST_GET(inst));
 
 DT_INST_FOREACH_STATUS_OKAY(NXP_VIDEO_SDMA_INIT)
diff --git a/drivers/video/video_stm32_dcmi.c b/drivers/video/video_stm32_dcmi.c
@@ -501,3 +501,5 @@ DEVICE_DT_INST_DEFINE(0, &video_stm32_dcmi_init,
 		    &video_stm32_dcmi_driver_api);
 
 VIDEO_DEVICE_DEFINE(dcmi, DEVICE_DT_INST_GET(0), video_stm32_dcmi_config_0.sensor_dev);
+
+VIDEO_MDEV_DEFINE(dcmi, DEVICE_DT_INST_GET(0));
diff --git a/drivers/video/video_sw_generator.c b/drivers/video/video_sw_generator.c
@@ -371,3 +371,5 @@ DEVICE_DEFINE(video_sw_generator, "VIDEO_SW_GENERATOR", &video_sw_generator_init
 	      &video_sw_generator_driver_api);
 
 VIDEO_DEVICE_DEFINE(video_sw_generator, DEVICE_GET(video_sw_generator), NULL);
+
+VIDEO_MDEV_DEFINE(video_sw_generator, DEVICE_GET(video_sw_generator));
diff --git a/include/zephyr/drivers/video.h b/include/zephyr/drivers/video.h
@@ -819,6 +819,26 @@ void video_closest_frmival_stepwise(const struct video_frmival_stepwise *stepwis
 void video_closest_frmival(const struct device *dev, enum video_endpoint_id ep,
 			   struct video_frmival_enum *match);
 
+/**
+ * @brief Get a video device by index
+ *
+ * The video subsystem keeps a list of registered video devices that application
+ * can use for streaming. This function is to get a video device in this list by
+ * specifying an index.
+ *
+ * @param i Index of the video device to get
+ */
+const struct device *video_get_dev(uint8_t i);
+
+/**
+ * @brief Get the number of registered video devices
+ *
+ * The video subsystem keeps a list of registered video devices that application
+ * can use for streaming. This function is to retrieve the size of this list.
+ *
+ */
+uint8_t video_get_devs_num(void);
+
 /**
  * @defgroup video_pixel_formats Video pixel formats
  * The '|' characters separate the pixels or logical blocks, and spaces separate the bytes.
diff --git a/samples/drivers/video/capture/boards/frdm_mcxn947_cpu0.overlay b/samples/drivers/video/capture/boards/frdm_mcxn947_cpu0.overlay
diff --git a/samples/drivers/video/capture/src/main.c b/samples/drivers/video/capture/src/main.c
@@ -92,22 +92,24 @@ int main(void)
 	size_t bsize;
 	int i = 0;
 	int err;
-
-#if DT_HAS_CHOSEN(zephyr_camera)
-	const struct device *const video_dev = DEVICE_DT_GET(DT_CHOSEN(zephyr_camera));
-
-	if (!device_is_ready(video_dev)) {
-		LOG_ERR("%s: video device is not ready", video_dev->name);
-		return 0;
+	const struct device *video_dev = NULL;
+	const struct device *const vsg = device_get_binding(VIDEO_DEV_SW);
+	uint8_t vdevs_num = video_get_devs_num();
+	bool found_vdev = false;
+
+	/* Get the 1st video HW available, otherwise fallbacks to video sw generator */
+	for (int j = 0; j < vdevs_num; j++) {
+		video_dev = video_get_dev(j);
+		if (device_is_ready(video_dev) && (vdevs_num == 1 || video_dev != vsg)) {
+			found_vdev = true;
+			break;
+		}
 	}
-#else
-	const struct device *const video_dev = device_get_binding(VIDEO_DEV_SW);
 
-	if (video_dev == NULL) {
-		LOG_ERR("%s: video device not found or failed to initialized", VIDEO_DEV_SW);
+	if (!found_vdev) {
+		LOG_ERR("No video device ready!");
 		return 0;
 	}
-#endif
 
 	LOG_INF("Video device: %s", video_dev->name);
 
diff --git a/samples/drivers/video/capture_to_lvgl/src/main.c b/samples/drivers/video/capture_to_lvgl/src/main.c
@@ -26,26 +26,29 @@ int main(void)
 	const struct device *video_dev;
 	size_t bsize;
 	int i = 0;
+	const struct device *const vsg = device_get_binding(VIDEO_DEV_SW);
+	uint8_t vdevs_num = video_get_devs_num();
+	bool found_vdev = false;
 
 	display_dev = DEVICE_DT_GET(DT_CHOSEN(zephyr_display));
 	if (!device_is_ready(display_dev)) {
 		LOG_ERR("Device not ready, aborting test");
 		return 0;
 	}
 
-#if DT_HAS_CHOSEN(zephyr_camera)
-	video_dev = DEVICE_DT_GET(DT_CHOSEN(zephyr_camera));
-	if (!device_is_ready(video_dev)) {
-		LOG_ERR("%s device is not ready", video_dev->name);
-		return 0;
+	/* Get the 1st video HW available, otherwise fallbacks to video sw generator */
+	for (int j = 0; j < vdevs_num; j++) {
+		video_dev = video_get_dev(j);
+		if (device_is_ready(video_dev) && (vdevs_num == 1 || video_dev != vsg)) {
+			found_vdev = true;
+			break;
+		}
 	}
-#else
-	video_dev = device_get_binding(VIDEO_DEV_SW);
-	if (video_dev == NULL) {
-		LOG_ERR("%s device not found", VIDEO_DEV_SW);
+
+	if (!found_vdev) {
+		LOG_ERR("No video device ready!");
 		return 0;
 	}
-#endif
 
 	LOG_INF("- Device name: %s", video_dev->name);
 
diff --git a/samples/drivers/video/tcpserversink/src/main.c b/samples/drivers/video/tcpserversink/src/main.c
@@ -42,21 +42,24 @@ int main(void)
 	int i, ret, sock, client;
 	struct video_format fmt;
 	struct video_caps caps;
-#if DT_HAS_CHOSEN(zephyr_camera)
-	const struct device *const video = DEVICE_DT_GET(DT_CHOSEN(zephyr_camera));
-
-	if (!device_is_ready(video)) {
-		LOG_ERR("%s: video device not ready.", video->name);
-		return 0;
+	const struct device *video = NULL;
+	const struct device *const vsg = device_get_binding(VIDEO_DEV_SW);
+	uint8_t vdevs_num = video_get_devs_num();
+	bool found_vdev = false;
+
+	/* Get the 1st video HW available, otherwise fallbacks to video sw generator */
+	for (int j = 0; j < vdevs_num; j++) {
+		video = video_get_dev(j);
+		if (device_is_ready(video) && (vdevs_num == 1 || video != vsg)) {
+			found_vdev = true;
+			break;
+		}
 	}
-#else
-	const struct device *const video = device_get_binding(VIDEO_DEV_SW);
 
-	if (video == NULL) {
-		LOG_ERR("%s: video device not found or failed to initialized.", VIDEO_DEV_SW);
+	if (!found_vdev) {
+		LOG_ERR("No video device ready!");
 		return 0;
 	}
-#endif
 	/* Prepare Network */
 	(void)memset(&addr, 0, sizeof(addr));
 	addr.sin_family = AF_INET;

Original file line number	Diff line number	Diff line change
`@@ -1,3 +1,4 @@`
`1`	`1`	`#include <zephyr/linker/iterable_sections.h>`
`2`	`2`
`3`	`3`	`ITERABLE_SECTION_RAM(video_device, Z_LINK_ITERABLE_SUBALIGN)`
	`4`	`+ITERABLE_SECTION_RAM(video_mdev, Z_LINK_ITERABLE_SUBALIGN)`