From 4922fdffbf736540550dadefb1ab8d106b1db69e Mon Sep 17 00:00:00 2001
From: Bjorn Andersson <bjorn.andersson@linaro.org>
Date: Tue, 28 Nov 2017 18:58:02 -0800
Subject: [PATCH] firehose: Write max_payload_size chunks at a time

Reduce the number of write operations by batching up sectors in a
max_payload_size sized buffer and write them in one chunk. Using the
qcserial driver will still chop up the USB traffic in 4kB chunks, so no
measurable perfomance improvement is seen.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
---
 firehose.c | 27 +++++++++++++++++++--------
 1 file changed, 19 insertions(+), 8 deletions(-)

diff --git a/firehose.c b/firehose.c
index befc1cf..0e9db0e 100644
--- a/firehose.c
+++ b/firehose.c
@@ -227,6 +227,8 @@ static int firehose_nop(int fd)
 	return firehose_read(fd, -1, firehose_nop_parser);
 }
 
+static size_t max_payload_size = 1048576;
+
 static int firehose_configure(int fd)
 {
 	xmlNode *root;
@@ -240,7 +242,7 @@ static int firehose_configure(int fd)
 
 	node = xmlNewChild(root, NULL, (xmlChar*)"configure", NULL);
 	xml_setpropf(node, "MemoryName", "ufs");
-	xml_setpropf(node, "MaxPayloadSizeToTargetInBytes", "%d", 1024 * 1024);
+	xml_setpropf(node, "MaxPayloadSizeToTargetInBytes", "%d", max_payload_size);
 	xml_setpropf(node, "verbose", "%d", 0);
 	xml_setpropf(node, "ZLPAwareHost", "%d", 0);
 
@@ -251,10 +253,14 @@ static int firehose_configure(int fd)
 	return firehose_read(fd, -1, firehose_nop_parser);
 }
 
+#define MIN(x, y) ((x) < (y) ? (x) : (y))
+#define ROUND_UP(x, a) (((x) + (a) - 1) & ~((a) - 1))
+
 static int firehose_program(int usbfd, struct program *program, int fd)
 {
 	unsigned num_sectors;
 	struct stat sb;
+	size_t chunk_size;
 	xmlNode *root;
 	xmlNode *node;
 	xmlDoc *doc;
@@ -272,7 +278,7 @@ static int firehose_program(int usbfd, struct program *program, int fd)
 		num_sectors = (sb.st_size + program->sector_size - 1) / program->sector_size;
 	}
 
-	buf = malloc(program->sector_size);
+	buf = malloc(max_payload_size);
 	if (!buf)
 		err(1, "failed to allocate sector buffer");
 
@@ -303,24 +309,29 @@ static int firehose_program(int usbfd, struct program *program, int fd)
 	t0 = time(NULL);
 
 	lseek(fd, program->file_offset * program->sector_size, SEEK_SET);
-	for (left = num_sectors; left > 0; left--) {
+	left = num_sectors;
+	while (left > 0) {
+		chunk_size = MIN(max_payload_size / program->sector_size, left);
+
 		if (fd >= 0) {
-			n = read(fd, buf, program->sector_size);
+			n = read(fd, buf, chunk_size * program->sector_size);
 			if (n < 0)
 				err(1, "failed to read");
 		} else {
 			n = 0;
 		}
 
-		if (n < program->sector_size)
-			memset(buf + n, 0, program->sector_size - n);
+		if (n < max_payload_size)
+			memset(buf + n, 0, max_payload_size - n);
 
-		n = write(usbfd, buf, program->sector_size);
+		n = write(usbfd, buf, chunk_size * program->sector_size);
 		if (n < 0)
 			err(1, "failed to write");
 
-		if (n != program->sector_size)
+		if (n != chunk_size * program->sector_size)
 			err(1, "failed to write full sector");
+
+		left -= chunk_size;
 	}
 
 	t = time(NULL) - t0;