X-Git-Url: https://git.ao2.it/libam7xxx.git/blobdiff_plain/9afe9f1293358f92483fba4c7052517e29f831aa..189a9391eb6cbc584cc0cc9d72dd4b91b9c71f4f:/src/am7xxx.c

diff --git a/src/am7xxx.c b/src/am7xxx.c
index 2ba9561..76df87d 100644
--- a/src/am7xxx.c
+++ b/src/am7xxx.c
@@ -53,7 +53,7 @@
 
 static void log_message(am7xxx_context *ctx,
 			int level,
-			const char *function,
+			const char *function_name,
 			int line,
 			const char *fmt,
 			...) __attribute__ ((format (printf, 5, 6)));
@@ -341,7 +341,7 @@ static inline unsigned int in_80chars(unsigned int i)
 {
 	/* The 3 below is the length of "xx " where xx is the hex string
 	 * representation of a byte */
-	return ((i+1) % (80/3));
+	return ((i + 1) % (80 / 3));
 }
 
 static void trace_dump_buffer(am7xxx_context *ctx, const char *message,
@@ -381,8 +381,9 @@ static void trace_dump_buffer(am7xxx_context *ctx, const char *message,
 static int read_data(am7xxx_device *dev, uint8_t *buffer, unsigned int len)
 {
 	int ret;
-	int transferred = 0;
+	int transferred;
 
+	transferred = 0;
 	ret = libusb_bulk_transfer(dev->usb_device, 0x81, buffer, len, &transferred, 0);
 	if (ret != 0 || (unsigned int)transferred != len) {
 		error(dev->ctx, "%s. Transferred: %d (expected %u)\n",
@@ -398,10 +399,11 @@ static int read_data(am7xxx_device *dev, uint8_t *buffer, unsigned int len)
 static int send_data(am7xxx_device *dev, uint8_t *buffer, unsigned int len)
 {
 	int ret;
-	int transferred = 0;
+	int transferred;
 
 	trace_dump_buffer(dev->ctx, "sending -->", buffer, len);
 
+	transferred = 0;
 	ret = libusb_bulk_transfer(dev->usb_device, 0x1, buffer, len, &transferred, 0);
 	if (ret != 0 || (unsigned int)transferred != len) {
 		error(dev->ctx, "%s. Transferred: %d (expected %u)\n",
@@ -489,8 +491,8 @@ static int send_data_async(am7xxx_device *dev, uint8_t *buffer, unsigned int len
 
 	/* Make a copy of the buffer so the caller can safely reuse it just
 	 * after libusb_submit_transfer() has returned. This technique
-	 * requires more allocations than a proper double-buffering approach
-	 * but it takes a lot less code. */
+	 * requires more dynamic allocations compared to a proper
+	 * double-buffering approach but it takes a lot less code. */
 	transfer_buffer = malloc(len);
 	if (transfer_buffer == NULL) {
 		error(dev->ctx, "cannot allocate transfer buffer (%s)\n",
@@ -626,7 +628,7 @@ static int send_command(am7xxx_device *dev, am7xxx_packet_type type)
  * set up */
 static void log_message(am7xxx_context *ctx,
 			int level,
-			const char *function,
+			const char *function_name,
 			int line,
 			const char *fmt,
 			...)
@@ -634,8 +636,8 @@ static void log_message(am7xxx_context *ctx,
 	va_list ap;
 
 	if (level == AM7XXX_LOG_FATAL || (ctx && level <= ctx->log_level)) {
-		if (function) {
-			fprintf(stderr, "%s", function);
+		if (function_name) {
+			fprintf(stderr, "%s", function_name);
 			if (line)
 				fprintf(stderr, "[%d]", line);
 			fprintf(stderr, ": ");
@@ -662,7 +664,7 @@ static am7xxx_device *add_new_device(am7xxx_context *ctx,
 
 	new_device = malloc(sizeof(*new_device));
 	if (new_device == NULL) {
-		fatal("cannot allocate a new device (%s)\n", strerror(errno));
+		debug(ctx, "cannot allocate a new device (%s)\n", strerror(errno));
 		return NULL;
 	}
 	memset(new_device, 0, sizeof(*new_device));
@@ -718,7 +720,6 @@ static int open_device(am7xxx_context *ctx,
 
 	/* the usb device has already been opened */
 	if ((*dev)->usb_device) {
-		debug(ctx, "(*dev)->usb_device already set\n");
 		ret = 1;
 		goto out;
 	}
@@ -744,13 +745,24 @@ static int open_device(am7xxx_context *ctx,
 
 	if (current_configuration != (*dev)->desc->configuration) {
 		/*
-		 * In principle kernel drivers bound to each interface should
-		 * be detached before setting the configuration, but in
-		 * practice this is not necessary for most devices.
+		 * In principle, before setting a new configuration, kernel
+		 * drivers should be detached from _all_ interfaces; for
+		 * example calling something like the following "invented"
+		 * function _before_ setting the new configuration:
 		 *
-		 * For example something like the following function would be
-		 * called:
-		 * 	libusb_detach_all_kernel_drivers((*dev)->usb_device);
+		 *   libusb_detach_all_kernel_drivers((*dev)->usb_device);
+		 *
+		 * However, in practice, this is not necessary for most
+		 * devices as they have only one configuration.
+		 *
+		 * When a device only has one configuration:
+		 *
+		 *   - if there was a kernel driver bound to the device, it
+		 *     had already set the configuration and the call below
+		 *     will be skipped;
+		 *
+		 *   - if no kernel driver was bound to the device, the call
+		 *     below will suceed.
 		 */
 		ret = libusb_set_configuration((*dev)->usb_device,
 					       (*dev)->desc->configuration);
@@ -788,7 +800,7 @@ static int open_device(am7xxx_context *ctx,
 	}
 
 	if (current_configuration != (*dev)->desc->configuration) {
-		debug(ctx, "libusb configuration changed (expected: %hhu, current: %hhu\n",
+		debug(ctx, "libusb configuration changed (expected: %hhu, current: %d\n",
 		      (*dev)->desc->configuration, current_configuration);
 		ret = -EINVAL;
 		goto out_libusb_release_interface;
@@ -1090,8 +1102,10 @@ AM7XXX_PUBLIC int am7xxx_init(am7xxx_context **ctx)
 	(*ctx)->log_level = AM7XXX_LOG_TRACE;
 
 	ret = libusb_init(&((*ctx)->usb_context));
-	if (ret < 0)
+	if (ret < 0) {
+		error(*ctx, "libusb_init failed: %s\n", libusb_error_name(ret));
 		goto out_free_context;
+	}
 
 	libusb_set_debug((*ctx)->usb_context, LIBUSB_LOG_LEVEL_INFO);