drivers: video: modifications needed to get it to work

This contains only the mandatory modifications to get the
drivers to work:

- expose `struct rtio_iodev_sqe` to the drivers so that the functions
  `rtio_iodev_sqe_ok()` and `rtio_iodev_sqe_err()` can be called.

- expose `stuct rtio_cqe` to the application so that the functions
  `rtio_cqe_release()` can be called with the same completion event (cqe)
  that was just dequeued.

The implementation can be different, but these points seems to be
mandatory to operate RTIO end-to-end.

Author: josuah

drivers/video/video_buffer.c

@@ -178,23 +178,15 @@ int video_enqueue(const struct device *dev, struct video_buffer *buf)
 	return 0;
 }
 
-int video_dequeue(struct video_buffer **buf)
+struct rtio_cqe *video_dequeue(void)
 {
-	struct rtio_cqe *cqe = rtio_cqe_consume_block(&rtio);
-	*buf = cqe->userdata;
-
-	if (cqe->result < 0) {
-		LOG_ERR("I/O operation failed");
-		return cqe->result;
-	}
-
-	return 0;
+	return rtio_cqe_consume_block(&rtio);
 }
 
-void video_release_buf()
+void video_release_buf(struct rtio_cqe *cqe)
 {
 	/* Buffer will be re-queued thanks to RTIO_SQE_MULTISHOT */
-	rtio_cqe_release(&rtio, rtio_cqe_consume_block(&rtio));
+	rtio_cqe_release(&rtio, cqe);
 }
 
 struct video_buffer *video_get_buf_sqe(struct mpsc *io_q)
@@ -217,6 +209,33 @@ struct video_buffer *video_get_buf_sqe(struct mpsc *io_q)
 	return sqe->userdata;
 }
 
+struct rtio_iodev_sqe *video_pop_io_q(struct mpsc *io_q)
+{
+	struct mpsc_node *node;
+	struct rtio_iodev_sqe *iodev_sqe;
+	struct video_buffer *vbuf;
+
+	node = mpsc_pop(io_q);
+	if (node == NULL) {
+		return NULL;
+	}
+
+	iodev_sqe = CONTAINER_OF(node, struct rtio_iodev_sqe, q);
+	vbuf = iodev_sqe->sqe.userdata;
+
+	__ASSERT_NO_MSG(vbuf != NULL);
+
+	if ((vbuf->type == VIDEO_BUF_TYPE_OUTPUT && iodev_sqe->sqe.op == RTIO_OP_RX) ||
+	    (vbuf->type == VIDEO_BUF_TYPE_INPUT && iodev_sqe->sqe.op == RTIO_OP_TX)) {
+		return iodev_sqe;
+	} else {
+		LOG_ERR("Unsupported RTIO operation (%d) or video buffer type (%d)",
+			iodev_sqe->sqe.op, vbuf->type);
+		rtio_iodev_sqe_err(iodev_sqe, -EINVAL);
+		return NULL;
+	}
+}
+
 static void video_iodev_submit(struct rtio_iodev_sqe *iodev_sqe)
 {
 	struct video_interface *vi = iodev_sqe->sqe.iodev->data;

drivers/video/video_buffer.h

@@ -5,3 +5,4 @@
  */
 
 struct video_buffer *video_get_buf_sqe(struct mpsc *io_q);
+struct rtio_iodev_sqe *video_pop_io_q(struct mpsc *io_q);

include/zephyr/drivers/video.h

@@ -28,6 +28,7 @@
 #include <zephyr/device.h>
 #include <zephyr/kernel.h>
 #include <zephyr/types.h>
+#include <zephyr/rtio/rtio.h>
 
 #ifdef __cplusplus
 extern "C" {
@@ -598,13 +599,11 @@ int video_enqueue(const struct device *dev, struct video_buffer *buf);
  *
  * @param buf Pointer a video buffer pointer.
  *
- * @retval 0 Is successful.
- * @retval -EINVAL If parameters are invalid.
- * @retval -EIO General input / output error.
+ * @retval The RTIO completion event with the completed buffer.
  */
-int video_dequeue(struct video_buffer **buf);
+struct rtio_cqe *video_dequeue(void);
 
-void video_release_buf();
+void video_release_buf(struct rtio_cqe *cqe);
 
 /**
  * @brief Flush endpoint buffers.

samples/drivers/video/capture/src/main.c

@@ -19,7 +19,7 @@
 
 LOG_MODULE_REGISTER(main, LOG_LEVEL_DBG);
 #else
-LOG_MODULE_REGISTER(main, CONFIG_LOG_DEFAULT_LEVEL);
+LOG_MODULE_REGISTER(main, LOG_LEVEL_DBG);
 #endif
 
 #if DT_HAS_CHOSEN(zephyr_display)
@@ -302,12 +302,15 @@ int main(void)
 
 	/* Grab video frames */
 	while (1) {
-		err = video_dequeue(&vbuf);
-		if (err) {
-			LOG_ERR("Unable to dequeue video buf");
+		struct rtio_cqe *cqe = video_dequeue();
+		struct video_buffer *vbuf = cqe->userdata;
+
+		if (cqe->result != 0) {
+			LOG_ERR("The video buffer of size %u completed with errors", vbuf->size);
 			return 0;
 		}
 
+
 		LOG_DBG("Got frame %u! size: %u; timestamp %u ms",
 			frame++, vbuf->bytesused, vbuf->timestamp);
 
@@ -321,6 +324,6 @@ int main(void)
 		video_display_frame(display_dev, vbuf, fmt);
 #endif
 
-		video_release_buf();
+		video_release_buf(cqe);
 	}
 }