[U-Boot] [PATCH 3/3] dfu: Introduction of the "dfu_checksum_method" env variable for checksum method setting

[Lukasz Majewski]

Up till now the CRC32 of received data was calculated unconditionally.
The standard crc32 implementation causes long delays when large images
were uploaded.

The "dfu_checksum_method" environment variable gives the opportunity to
enable on demand (when e.g. debugging) the crc32 calculation.
It can be done without need to recompile the u-boot binary.

By default the crc32 is not calculated.

Tests results:
400 MiB ums.img file
With 		crc32 calculation: 65 sec [avg 6.29 MB/s]
Without 		crc32 calculation: 25 sec [avg 16.17 MB/s]

Signed-off-by: Lukasz Majewski <l.majewski at samsung.com>
---
 drivers/dfu/dfu.c |   34 ++++++++++++++++++++++++++++++----
 include/dfu.h     |    5 +++++
 2 files changed, 35 insertions(+), 4 deletions(-)

diff --git a/drivers/dfu/dfu.c b/drivers/dfu/dfu.c
index e15f959..5d50b47 100644
--- a/drivers/dfu/dfu.c
+++ b/drivers/dfu/dfu.c
@@ -20,6 +20,7 @@ static bool dfu_reset_request;
 static LIST_HEAD(dfu_list);
 static int dfu_alt_num;
 static int alt_num_count;
+static int dfu_checksum_method;
 
 bool dfu_reset(void)
 {
@@ -99,6 +100,23 @@ unsigned char *dfu_get_buf(void)
 	return dfu_buf;
 }
 
+static int dfu_get_checksum_method(void)
+{
+	char *s;
+
+	s = getenv("dfu_checksum_method");
+	if (!s)
+		return DFU_NO_CHECKSUM;
+
+	if (!strcmp(s, "crc32")) {
+		debug("%s: DFU checksum method: %s\n", __func__, s);
+		return DFU_CRC32;
+	} else {
+		error("DFU checksum method: %s not supported!\n", s);
+		return -EINVAL;
+	}
+}
+
 static int dfu_write_buffer_drain(struct dfu_entity *dfu)
 {
 	long w_size;
@@ -109,8 +127,8 @@ static int dfu_write_buffer_drain(struct dfu_entity *dfu)
 	if (w_size == 0)
 		return 0;
 
-	/* update CRC32 */
-	dfu->crc = crc32(dfu->crc, dfu->i_buf_start, w_size);
+	if (dfu_checksum_method == DFU_CRC32)
+		dfu->crc = crc32(dfu->crc, dfu->i_buf_start, w_size);
 
 	ret = dfu->write_medium(dfu, dfu->offset, dfu->i_buf_start, &w_size);
 	if (ret)
@@ -234,7 +252,8 @@ static int dfu_read_buffer_fill(struct dfu_entity *dfu, void *buf, int size)
 		/* consume */
 		if (chunk > 0) {
 			memcpy(buf, dfu->i_buf, chunk);
-			dfu->crc = crc32(dfu->crc, buf, chunk);
+			if (dfu_checksum_method == DFU_CRC32)
+				dfu->crc = crc32(dfu->crc, buf, chunk);
 			dfu->i_buf += chunk;
 			dfu->b_left -= chunk;
 			dfu->r_left -= chunk;
@@ -318,7 +337,9 @@ int dfu_read(struct dfu_entity *dfu, void *buf, int size, int blk_seq_num)
 	}
 
 	if (ret < size) {
-		debug("%s: %s CRC32: 0x%x\n", __func__, dfu->name, dfu->crc);
+		if (dfu_checksum_method == DFU_CRC32)
+			debug("%s: %s CRC32: 0x%x\n", __func__, dfu->name,
+			      dfu->crc);
 		puts("\nUPLOAD ... done\nCtrl+C to exit ...\n");
 
 		dfu_free_buf();
@@ -393,6 +414,11 @@ int dfu_config_entities(char *env, char *interface, int num)
 	dfu_alt_num = dfu_find_alt_num(env);
 	debug("%s: dfu_alt_num=%d\n", __func__, dfu_alt_num);
 
+	ret = dfu_get_checksum_method();
+	if (ret < 0)
+		return ret;
+	dfu_checksum_method = ret;
+
 	dfu = calloc(sizeof(*dfu), dfu_alt_num);
 	if (!dfu)
 		return -1;
diff --git a/include/dfu.h b/include/dfu.h
index 751f0fd..855d6dc 100644
--- a/include/dfu.h
+++ b/include/dfu.h
@@ -37,6 +37,11 @@ enum dfu_op {
 	DFU_OP_WRITE,
 };
 
+enum dfu_checksum {
+	DFU_NO_CHECKSUM = 0,
+	DFU_CRC32,
+};
+
 #define DFU_NOT_SUPPORTED -1
 
 struct mmc_internal_data {
-- 
1.7.10.4