samples: usb: uvc: add indirection for UVC source device

In preparation for the introduction of video encoder support
add an indirection for handling of the buffers of the UVC
source device. Currently this is only video_dev however it
can also be an encoder device when encoder is introduced
between video capture device and the UVC device.

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

Author: Alain Volmat

samples/subsys/usb/uvc/src/main.c

@@ -23,6 +23,11 @@ const static struct device *const video_dev = DEVICE_DT_GET(DT_CHOSEN(zephyr_cam
 /* Format capabilities of video_dev, used everywhere through the sample */
 static struct video_caps video_caps = {.type = VIDEO_BUF_TYPE_OUTPUT};
 
+static const struct device *app_uvc_source_dev(void)
+{
+	return video_dev;
+}
+
 /* Pixel formats present in one of the UVC 1.5 standard */
 static bool app_is_supported_format(uint32_t pixfmt)
 {
@@ -46,6 +51,7 @@ static bool app_has_supported_format(void)
 
 static void app_add_format(uint32_t pixfmt, uint32_t width, uint32_t height, bool has_sup_fmts)
 {
+	const struct device *uvc_src_dev = app_uvc_source_dev();
 	struct video_format fmt = {
 		.pixelformat = pixfmt,
 		.width = width,
@@ -60,7 +66,7 @@ static void app_add_format(uint32_t pixfmt, uint32_t width, uint32_t height, boo
 	}
 
 	/* Set the format to get the size */
-	ret = video_set_compose_format(video_dev, &fmt);
+	ret = video_set_compose_format(uvc_src_dev, &fmt);
 	if (ret != 0) {
 		LOG_ERR("Could not set the format of %s to %s %ux%u (size %u)",
 			video_dev->name, VIDEO_FOURCC_TO_STR(fmt.pixelformat),
@@ -141,6 +147,7 @@ static void app_add_filtered_formats(void)
 
 int main(void)
 {
+	const struct device *uvc_src_dev = app_uvc_source_dev();
 	struct usbd_context *sample_usbd;
 	struct video_buffer *vbuf;
 	struct video_format fmt = {0};
@@ -162,7 +169,7 @@ int main(void)
 	}
 
 	/* Must be called before usb_enable() */
-	uvc_set_video_dev(uvc_dev, video_dev);
+	uvc_set_video_dev(uvc_dev, uvc_src_dev);
 
 	/* Must be called before usb_enable() */
 	app_add_filtered_formats();
@@ -269,17 +276,19 @@ int main(void)
 			return ret;
 		}
 
-		ret = video_transfer_buffer(video_dev, uvc_dev,
+		ret = video_transfer_buffer(uvc_src_dev, uvc_dev,
 					    VIDEO_BUF_TYPE_OUTPUT, VIDEO_BUF_TYPE_INPUT, K_NO_WAIT);
 		if (ret != 0 && ret != -EAGAIN) {
-			LOG_ERR("Failed to transfer from %s to %s", video_dev->name, uvc_dev->name);
+			LOG_ERR("Failed to transfer from %s to %s",
+				uvc_src_dev->name, uvc_dev->name);
 			return ret;
 		}
 
-		ret = video_transfer_buffer(uvc_dev, video_dev,
+		ret = video_transfer_buffer(uvc_dev, uvc_src_dev,
 					    VIDEO_BUF_TYPE_INPUT, VIDEO_BUF_TYPE_OUTPUT, K_NO_WAIT);
 		if (ret != 0 && ret != -EAGAIN) {
-			LOG_ERR("Failed to transfer from %s to %s", uvc_dev->name, video_dev->name);
+			LOG_ERR("Failed to transfer from %s to %s",
+				uvc_dev->name, uvc_src_dev->name);
 			return ret;
 		}