From dff6d0c5144740ea47b92293306a3bb03a2a62b7 Mon Sep 17 00:00:00 2001
From: Jef Driesen <jef@libdivecomputer.org>
Date: Thu, 12 Mar 2020 21:41:17 +0100
Subject: [PATCH] Read and cache the firmware version information

By reading the firmware version information immediately after entering
download or service mode, we can identify the specific firmware version
and adapt to minor differences in the communication protocol.
---
 src/hw_ostc3.c | 34 ++++++++++++++++++++--------------
 1 file changed, 20 insertions(+), 14 deletions(-)

diff --git a/src/hw_ostc3.c b/src/hw_ostc3.c
index 0b980e7..e348514 100644
--- a/src/hw_ostc3.c
+++ b/src/hw_ostc3.c
@@ -96,6 +96,8 @@ typedef struct hw_ostc3_device_t {
 	unsigned int hardware;
 	unsigned int feature;
 	unsigned int model;
+	unsigned int serial;
+	unsigned int firmware;
 	unsigned char fingerprint[5];
 	hw_ostc3_state_t state;
 	unsigned char cache[20];
@@ -372,6 +374,8 @@ hw_ostc3_device_open (dc_device_t **out, dc_context_t *context, dc_iostream_t *i
 	device->hardware = INVALID;
 	device->feature = 0;
 	device->model = 0;
+	device->serial = 0;
+	device->firmware = 0;
 	memset (device->fingerprint, 0, sizeof (device->fingerprint));
 	memset (device->cache, 0, sizeof (device->cache));
 	device->available = 0;
@@ -546,10 +550,24 @@ hw_ostc3_device_init (hw_ostc3_device_t *device, hw_ostc3_state_t state)
 		return rc;
 	}
 
+	// Read the version information.
+	unsigned char version[SZ_VERSION] = {0};
+	rc = hw_ostc3_transfer (device, NULL, IDENTITY, NULL, 0, version, sizeof(version), NODELAY);
+	if (rc != DC_STATUS_SUCCESS) {
+		ERROR (abstract->context, "Failed to read the version information.");
+		return rc;
+	}
+
 	// Cache the descriptor.
 	device->hardware = array_uint16_be(hardware + 0);
 	device->feature = array_uint16_be(hardware + 2);
 	device->model = hardware[4];
+	device->serial = array_uint16_le (version + 0);
+	if (device->hardware == OSTC4) {
+		device->firmware = array_uint16_le (version + 2);
+	} else {
+		device->firmware = array_uint16_be (version + 2);
+	}
 
 	return DC_STATUS_SUCCESS;
 }
@@ -654,22 +672,10 @@ hw_ostc3_device_foreach (dc_device_t *abstract, dc_dive_callback_t callback, voi
 	if (rc != DC_STATUS_SUCCESS)
 		return rc;
 
-	// Download the version data.
-	unsigned char id[SZ_VERSION] = {0};
-	rc = hw_ostc3_device_version (abstract, id, sizeof (id));
-	if (rc != DC_STATUS_SUCCESS) {
-		ERROR (abstract->context, "Failed to read the version.");
-		return rc;
-	}
-
 	// Emit a device info event.
 	dc_event_devinfo_t devinfo;
-	if (device->hardware == OSTC4) {
-		devinfo.firmware = array_uint16_le (id + 2);
-	} else {
-		devinfo.firmware = array_uint16_be (id + 2);
-	}
-	devinfo.serial = array_uint16_le (id + 0);
+	devinfo.firmware = device->firmware;
+	devinfo.serial = device->serial;
 	if (device->hardware != UNKNOWN) {
 		devinfo.model = device->hardware;
 	} else {