usb: device: gs_usb: make capturing hardware timestamp on sof optional

Make the capturing of hardware timestamps on USB Start of Frame (SoF) events optional and disable it by default. Capturing the hardware timestamp on SoF improves the accuracy of the time synchronization between the USB host and the device (in the range of ~110 to 20 microseconds depending on the board according to my measurements), but comes with a cost of much higher CPU load. This does not affect the relative timestamping of CAN RX/TX frames, only their absolute timestamp as compared to the USB host time. Signed-off-by: Henrik Brix Andersen <[email protected]>
CANnectivity · Sep 4, 2024 · 92db3f3 · 92db3f3
1 parent 4ca426d
commit 92db3f3
Show file tree

Hide file tree

Showing 5 changed files with 47 additions and 11 deletions.
diff --git a/app/sample.yaml b/app/sample.yaml
@@ -16,6 +16,12 @@ tests:
       - frdm_k64f
       - lpcxpresso55s16
       - nucleo_h723zg
+  app.cannectivity.sof:
+    depends_on: usb_device can
+    integration_platforms:
+      - nucleo_h723zg
+    extra_configs:
+      - CONFIG_USB_DEVICE_GS_USB_TIMESTAMP_SOF=y
   app.cannectivity.release:
     depends_on: usb_device can
     extra_args:
@@ -31,6 +37,14 @@ tests:
     integration_platforms:
       - frdm_k64f
       - lpcxpresso55s16
+  app.cannectivity.usbd_next.sof:
+    depends_on: usbd can
+    extra_args:
+      - FILE_SUFFIX=usbd_next
+    integration_platforms:
+      - lpcxpresso55s16
+    extra_configs:
+      - CONFIG_USBD_GS_USB_TIMESTAMP_SOF=y
   app.cannectivity.usbd_next.release:
     depends_on: usbd can
     extra_args:

diff --git a/subsys/usb/device/class/Kconfig.gs_usb b/subsys/usb/device/class/Kconfig.gs_usb
@@ -43,10 +43,17 @@ config USB_DEVICE_GS_USB_IDENTIFICATION
 
 config USB_DEVICE_GS_USB_TIMESTAMP
 	bool "Enable support for hardware timestamps"
-	imply USB_DEVICE_SOF
 	help
 	  Enable support for hardware timestamps provided by the application.
 
+config USB_DEVICE_GS_USB_TIMESTAMP_SOF
+	bool "Capture hardware timestamp on USB SoF"
+	depends on USB_DEVICE_GS_USB_TIMESTAMP
+	select USB_DEVICE_SOF
+	help
+	  Capture the hardware timestamp on each USB Start of Frame event. This improves the
+	  timestamp accurracy with the cost of a higher CPU load.
+
 config USB_DEVICE_GS_USB_TERMINATION
 	bool "Enable support for CAN bus termination resistors"
 	help

diff --git a/subsys/usb/device/class/gs_usb.c b/subsys/usb/device/class/gs_usb.c
@@ -53,10 +53,10 @@ struct gs_usb_data {
 	void *user_data;
 	struct net_buf_pool *pool;
 
-#ifdef CONFIG_USB_DEVICE_GS_USB_TIMESTAMP
+#ifdef CONFIG_USB_DEVICE_GS_USB_TIMESTAMP_SOF
 	uint32_t timestamp;
 	bool sof_seen;
-#endif /* CONFIG_USB_DEVICE_GS_USB_TIMESTAMP */
+#endif /* CONFIG_USB_DEVICE_GS_USB_TIMESTAMP_SOF */
 
 	struct k_fifo rx_fifo;
 	struct k_thread rx_thread;
@@ -648,17 +648,21 @@ static int gs_usb_request_timestamp(const struct device *dev, int32_t *tlen, uin
 		return -ENOTSUP;
 	}
 
+#ifdef CONFIG_USB_DEVICE_GS_USB_TIMESTAMP_SOF
 	if (data->sof_seen) {
 		timestamp = data->timestamp;
 		data->sof_seen = false;
 	} else {
+#endif /* CONFIG_USB_DEVICE_GS_USB_TIMESTAMP_SOF */
 		err = data->ops.timestamp(dev, &timestamp, data->user_data);
 		if (err != 0) {
 			LOG_ERR("failed to get current timestamp (err %d)", err);
 			return err;
 		}
+#ifdef CONFIG_USB_DEVICE_GS_USB_TIMESTAMP_SOF
 		LOG_WRN_ONCE("USB SoF event not supported, timestamp will be less accurate");
 	}
+#endif /* CONFIG_USB_DEVICE_GS_USB_TIMESTAMP_SOF */
 
 	LOG_DBG("timestamp: 0x%08x", timestamp);
 
@@ -1370,7 +1374,7 @@ static void gs_usb_status_callback(struct usb_cfg_data *cfg, enum usb_dc_status_
 		LOG_DBG("USB device clear halt");
 		break;
 	case USB_DC_SOF:
-#ifdef CONFIG_USB_DEVICE_GS_USB_TIMESTAMP
+#ifdef CONFIG_USB_DEVICE_GS_USB_TIMESTAMP_SOF
 		int err;
 
 		if (data->ops.timestamp != NULL) {
@@ -1383,7 +1387,7 @@ static void gs_usb_status_callback(struct usb_cfg_data *cfg, enum usb_dc_status_
 			/* Not all USB device controller drivers support SoF events */
 			data->sof_seen = true;
 		}
-#endif /* CONFIG_USB_DEVICE_GS_USB_TIMESTAMP */
+#endif /* CONFIG_USB_DEVICE_GS_USB_TIMESTAMP_SOF */
 		break;
 	case USB_DC_UNKNOWN:
 		__fallthrough;

diff --git a/subsys/usb/device_next/class/Kconfig.gs_usb b/subsys/usb/device_next/class/Kconfig.gs_usb
@@ -47,6 +47,13 @@ config USBD_GS_USB_TIMESTAMP
 	help
 	  Enable support for hardware timestamps provided by the application.
 
+config USBD_GS_USB_TIMESTAMP_SOF
+	bool "Capture hardware timestamp on USB SoF"
+	depends on USBD_GS_USB_TIMESTAMP
+	help
+	  Capture the hardware timestamp on each USB Start of Frame event. This improves the
+	  timestamp accurracy with the cost of a higher CPU load.
+
 config USBD_GS_USB_TERMINATION
 	bool "Enable support for CAN bus termination resistors"
 	help

diff --git a/subsys/usb/device_next/class/gs_usb.c b/subsys/usb/device_next/class/gs_usb.c
@@ -62,10 +62,10 @@ struct gs_usb_data {
 	struct net_buf_pool *pool;
 
 	atomic_t state;
-#ifdef CONFIG_USBD_GS_USB_TIMESTAMP
+#ifdef CONFIG_USBD_GS_USB_TIMESTAMP_SOF
 	uint32_t timestamp;
 	bool sof_seen;
-#endif /* CONFIG_USBD_GS_USB_TIMESTAMP */
+#endif /* CONFIG_USBD_GS_USB_TIMESTAMP_SOF */
 
 	struct k_sem in_sem;
 	struct k_fifo rx_fifo;
@@ -638,7 +638,7 @@ static int gs_usb_request_device_config(const struct device *dev, struct net_buf
 	return 0;
 }
 
-#ifdef CONFIG_USBD_GS_USB_TIMESTAMP
+#ifdef CONFIG_USBD_GS_USB_TIMESTAMP_SOF
 static void gs_usb_sof(struct usbd_class_data *const c_data)
 {
 	const struct device *dev = usbd_class_get_private(c_data);
@@ -658,7 +658,7 @@ static void gs_usb_sof(struct usbd_class_data *const c_data)
 	/* Not all USB device controller drivers support SoF events */
 	data->sof_seen = true;
 }
-#endif /* CONFIG_USBD_GS_USB_TIMESTAMP */
+#endif /* CONFIG_USBD_GS_USB_TIMESTAMP_SOF */
 
 static int gs_usb_request_timestamp(const struct device *dev, struct net_buf *buf)
 {
@@ -672,17 +672,21 @@ static int gs_usb_request_timestamp(const struct device *dev, struct net_buf *bu
 		return -ENOTSUP;
 	}
 
+#ifdef CONFIG_USBD_GS_USB_TIMESTAMP_SOF
 	if (data->sof_seen) {
 		timestamp = data->timestamp;
 		data->sof_seen = false;
 	} else {
+#endif /* CONFIG_USBD_GS_USB_TIMESTAMP_SOF */
 		err = data->ops.timestamp(dev, &timestamp, data->user_data);
 		if (err != 0) {
 			LOG_ERR("failed to get current timestamp (err %d)", err);
 			return err;
 		}
+#ifdef CONFIG_USBD_GS_USB_TIMESTAMP_SOF
 		LOG_WRN_ONCE("USB SoF event not supported, timestamp will be less accurate");
 	}
+#endif /* CONFIG_USBD_GS_USB_TIMESTAMP_SOF */
 
 	LOG_DBG("timestamp: 0x%08x", timestamp);
 	net_buf_add_le32(buf, timestamp);
@@ -1558,9 +1562,9 @@ struct usbd_class_api gs_usb_api = {
 	.control_to_dev = gs_usb_control_to_dev,
 	.control_to_host = gs_usb_control_to_host,
 	.request = gs_usb_request,
-#ifdef CONFIG_USBD_GS_USB_TIMESTAMP
+#ifdef CONFIG_USBD_GS_USB_TIMESTAMP_SOF
 	.sof = gs_usb_sof,
-#endif /* CONFIG_USBD_GS_USB_TIMESTAMP */
+#endif /* CONFIG_USBD_GS_USB_TIMESTAMP_SOF */
 	.enable = gs_usb_enable,
 	.disable = gs_usb_disable,
 	.get_desc = gs_usb_get_desc,