[PATCH 2/3] MTD: spi-nor: check for short writes in spi_nor_write.

[Michal Suchanek]

My SPI controller driver does not support DMA so writes are truncated to
FIFO size.
Check the amount of data actually written by the driver.

Signed-off-by: Michal Suchanek <hramrach at gmail.com>
---
 drivers/mtd/spi-nor/spi-nor.c | 42 +++++++++++++++++-------------------------
 1 file changed, 17 insertions(+), 25 deletions(-)

diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
index 14a5d23..75904b5 100644
--- a/drivers/mtd/spi-nor/spi-nor.c
+++ b/drivers/mtd/spi-nor/spi-nor.c
@@ -807,7 +807,7 @@ static int spi_nor_write(struct mtd_info *mtd, loff_t to, size_t len,
 	size_t *retlen, const u_char *buf)
 {
 	struct spi_nor *nor = mtd_to_spi_nor(mtd);
-	u32 page_offset, page_size, i;
+	u32 page_offset, page_remainder, page_size, i;
 	int ret;
 
 	dev_dbg(nor->dev, "to 0x%08x, len %zd\n", (u32)to, len);
@@ -816,36 +816,28 @@ static int spi_nor_write(struct mtd_info *mtd, loff_t to, size_t len,
 	if (ret)
 		return ret;
 
-	write_enable(nor);
-
-	page_offset = to & (nor->page_size - 1);
-
-	/* do all the bytes fit onto one page? */
-	if (page_offset + len <= nor->page_size) {
-		nor->write(nor, to, len, retlen, buf);
-	} else {
-		/* the size of data remaining on the first page */
-		page_size = nor->page_size - page_offset;
-		nor->write(nor, to, page_size, retlen, buf);
+	/* write everything in nor->page_size chunks */
+	/* check the size of data actually written */
+	for (i = 0; i < len; i += *retlen) {
+		page_size = len - i;
+		page_offset = (to + i) & (nor->page_size - 1);
+		page_remainder = nor->page_size - page_offset;
+		if (page_size > nor->page_size)
+			page_size = nor->page_size;
+		if (page_remainder && (page_size > page_remainder))
+			page_size = page_remainder;
 
-		/* write everything in nor->page_size chunks */
-		for (i = page_size; i < len; i += page_size) {
-			page_size = len - i;
-			if (page_size > nor->page_size)
-				page_size = nor->page_size;
-
-			ret = spi_nor_wait_till_ready(nor);
-			if (ret)
-				goto write_err;
+		write_enable(nor);
 
-			write_enable(nor);
+		nor->write(nor, to + i, page_size, retlen, buf + i);
 
-			nor->write(nor, to + i, page_size, retlen, buf + i);
-		}
+		ret = spi_nor_wait_till_ready(nor);
+		if (ret)
+			goto write_err;
 	}
 
-	ret = spi_nor_wait_till_ready(nor);
 write_err:
+	*retlen = i;
 	spi_nor_unlock_and_unprep(nor, SPI_NOR_OPS_WRITE);
 	return ret;
 }
-- 
2.1.4