Use USB MaxPacketSize

Use USB MaxPacketSize to save memory for full speed devices

Author: ExtremeGTX

samples/subsys/usb/mtp/app.overlay

@@ -313,10 +313,13 @@ static int usbd_mtp_init(struct usbd_class_data *c_data)
 
 	device_version = "1.0";
 
-	LOG_DBG("Desc data: Manufacturer: %s, Product: %s, SN: %s",
+	mtp_ctx->max_packet_size = usbd_desc->bMaxPacketSize0;
+
+	LOG_DBG("Desc data: Manufacturer: %s, Product: %s, SN: %s, PktSize: %u",
 			manufacturer,
 			model,
-			d_nd->bLength > 0 ? serial_number : "NULL");
+			d_nd->bLength > 0 ? serial_number : "NULL",
+			mtp_ctx->max_packet_size);
 
 	mtp_init(mtp_ctx, manufacturer, model, device_version, serial_number);
 

subsys/usb/device_next/class/usbd_mtp.c

@@ -113,7 +113,6 @@ LOG_MODULE_REGISTER(usb_mtp_impl, CONFIG_USBD_MTP_LOG_LEVEL);
 
 /* MACROS */
 #define MAX_FILES                CONFIG_USBD_MTP_MAX_HANDLES
-#define MAX_PACKET_SIZE          512 /* Get it in a usb complaint way */
 
 #define INTERNAL_STORAGE_ID(id)  (0x00010000 + id)
 #define REMOVABLE_STORAGE_ID(id) (0x00020000 + id)
@@ -844,12 +843,12 @@ MTP_CMD_HANDLER(MTP_OP_GET_OBJECT_INFO)
 static int continue_get_object(struct mtp_context* ctx, struct net_buf *buf)
 {
 	int len = 0;
-	int total_chunks = (ctx->filestate.total_size / MAX_PACKET_SIZE);
+	int total_chunks = (ctx->filestate.total_size / ctx->max_packet_size);
 
 	memset(ctx->filebuf, 0x00, 512);
 
 	if (ctx->filestate.transferred < ctx->filestate.total_size) {
-		len = MIN(MAX_PACKET_SIZE,
+		len = MIN(ctx->max_packet_size,
 			  (ctx->filestate.total_size - ctx->filestate.transferred));
 
 		int read = fs_read(&ctx->filestate.file, ctx->filebuf, len);
@@ -920,7 +919,7 @@ MTP_CMD_HANDLER(MTP_OP_GET_OBJECT)
 	}
 
 	uint32_t filesize = storage[storage_id].filelist[object_id].size;
-	uint32_t available_buf_len = MAX_PACKET_SIZE - sizeof(struct mtp_header);
+	uint32_t available_buf_len = ctx->max_packet_size - sizeof(struct mtp_header);
 
 	LOG_DBG("Sending file: %s size: %u", path, storage[storage_id].filelist[object_id].size);
 

subsys/usb/device_next/class/usbd_mtp_class.c

@@ -13,7 +13,13 @@
 
 struct mtp_context {
 	bool session_opened;
-	uint8_t filebuf[512]; /* TODO: should match USB Packet size */
+	uint16_t max_packet_size;
+	uint8_t filebuf[512]; /* Use USB HS MPS */
+	uint16_t cmd;
+
+	bool more_data_needed;
+	int (*extra_data_fn)(struct mtp_context* ctx, struct net_buf *buf_in);
+	int (*pending_fn)(struct mtp_context* ctx, struct net_buf *buf);
 	struct {
 		struct fs_file_t file;
 		char filepath[MAX_PATH_LEN];
@@ -23,11 +29,6 @@ struct mtp_context {
 		uint32_t storage_id;
 	} filestate;
 
-	uint16_t cmd;
-	uint16_t cmd_result;
-        bool more_data_needed;
-        int (*extra_data_fn)(struct mtp_context* ctx, struct net_buf *buf_in);
-        int (*pending_fn)(struct mtp_context* ctx, struct net_buf *buf);
 };