video: stm32_dcmi: When to do what in recovery

@josuah, @avolmat-st @pillo79 and all -

This commit is giving a couple different options on what should
be done when we detect a USB failure.  The previous one, when
the callback for DMA error happens, I stopped the HDMA DMA and
in some case restarted it there.

But I found when I started doing the Snapshot earlier, I found it
would hang more often when it was done there, so I did it when
the call came back to get a buffer in the dequeue... So the new
option is to detect the error and set a state saying we
are in an error condition and when we return and are in
the dequeue function, if we see that that we errored out
it process it then.  In the case of not being in snapshot
mode there are two place.  Again when:
```
*vbuf = k_fifo_get(&data->fifo_out, timeout);
```
returns in this condition.  So we do it there.

Or if we call dequeue and the error happened while we were not
in dequeue, like we have two buffers.  And we already dequeue
one and maybe we re drawing it on the display and the
camera is still active reading in the next frame.

Once I know which way you would all prefer, will then
remove the others and squash the commits.

Signed-off-by: Kurt Eckhardt <[email protected]>

Author: KurtE

drivers/video/video_stm32_dcmi.c

@@ -6,6 +6,10 @@
 
 #define DT_DRV_COMPAT st_stm32_dcmi
 
+/* *** Experiment to see when best to stop/start in error *** */
+/*
+ *#define STOP_DMA_IN_ERROR_CBS
+ */
 #include <errno.h>
 
 #include <zephyr/kernel.h>
@@ -66,6 +70,7 @@ static void stm32_dcmi_process_dma_error(DCMI_HandleTypeDef *hdcmi)
 		return;
 	}
 
+#ifdef STOP_DMA_IN_ERROR_CBS
 	/* Lets try to recover by stopping and maybe restart */
 	if (HAL_DCMI_Stop(hdcmi) != HAL_OK) {
 		LOG_WRN("HAL_DCMI_Stop FAILED!");
@@ -82,12 +87,16 @@ static void stm32_dcmi_process_dma_error(DCMI_HandleTypeDef *hdcmi)
 	}
 	/* also cancel timeout on the fifo_out to speed up recovery */
 	k_fifo_cancel_wait(&dev_data->fifo_out);
+#else
+	dev_data->restart_dma = true;
+	k_fifo_cancel_wait(&dev_data->fifo_out);
+#endif
 }
 
 void HAL_DCMI_ErrorCallback(DCMI_HandleTypeDef *hdcmi)
 {
 	LOG_WRN("%s %p", __func__, hdcmi);
-	/*stm32_dcmi_process_dma_error(hdcmi); */
+	stm32_dcmi_process_dma_error(hdcmi);
 }
 
 void HAL_DCMI_FrameEventCallback(DCMI_HandleTypeDef *hdcmi)
@@ -348,6 +357,7 @@ static int video_stm32_dcmi_dequeue(const struct device *dev, struct video_buffe
 		if (data->vbuf == NULL) {
 			data->vbuf = k_fifo_get(&data->fifo_in, K_NO_WAIT);
 			if (data->vbuf == NULL) {
+				LOG_WRN("Snapshot: No Buffers available!");
 				return -ENOMEM;
 			}
 
@@ -363,6 +373,12 @@ static int video_stm32_dcmi_dequeue(const struct device *dev, struct video_buffe
 	} else {
 		if (data->restart_dma) {
 			/* error on last transfer try to restart it */
+			LOG_INF("Dequeue recover at start");
+#ifndef STOP_DMA_IN_ERROR_CBS
+			if (HAL_DCMI_Stop(&data->hdcmi) != HAL_OK) {
+				LOG_WRN("HAL_DCMI_Stop FAILED!");
+			}
+#endif
 			if (HAL_DCMI_Start_DMA(&data->hdcmi, DCMI_MODE_CONTINUOUS,
 					       (uint32_t)data->vbuf->buffer,
 					       data->vbuf->size / 4) != HAL_OK) {
@@ -375,6 +391,31 @@ static int video_stm32_dcmi_dequeue(const struct device *dev, struct video_buffe
 
 	*vbuf = k_fifo_get(&data->fifo_out, timeout);
 
+#ifndef STOP_DMA_IN_ERROR_CBS
+	if (data->restart_dma) {
+		LOG_INF("Dequeue recover after k_fifo_get");
+		/* Lets try to recover by stopping and maybe restart */
+		if (HAL_DCMI_Stop(&data->hdcmi) != HAL_OK) {
+			LOG_WRN("HAL_DCMI_Stop FAILED!");
+		}
+
+		if (data->snapshot_mode) {
+			if (data->vbuf != NULL) {
+				k_fifo_put(&data->fifo_in, data->vbuf);
+				data->vbuf = NULL;
+			}
+		} else {
+			/* error on last transfer try to restart it */
+			if (HAL_DCMI_Start_DMA(&data->hdcmi, DCMI_MODE_CONTINUOUS,
+					       (uint32_t)data->vbuf->buffer,
+					       data->vbuf->size / 4) != HAL_OK) {
+				LOG_WRN("Snapshot: HAL_DCMI_Start_DMA FAILED!");
+				return -EIO;
+			}
+		}
+		data->restart_dma = false;
+	}
+#endif
 	if (*vbuf == NULL) {
 		return -EAGAIN;
 	}
@@ -384,7 +425,6 @@ static int video_stm32_dcmi_dequeue(const struct device *dev, struct video_buffe
 			LOG_WRN("Snapshot: HAL_DCMI_Stop FAILED!");
 		}
 	}
-
 	return 0;
 }