From: Felix Fietkau <nbd@nbd.name>
Date: Thu, 22 Feb 2018 11:11:57 +0100
Subject: [PATCH] mtd: spi-nor: allow NOR driver to write fewer bytes than
 requested

The write size can be constrained by the maximum message/transfer size
of the SPI controller. Only check for ret = 0 to avoid an infinite loop.

Signed-off-by: Felix Fietkau <nbd@nbd.name>
---

--- a/drivers/mtd/spi-nor/spi-nor.c
+++ b/drivers/mtd/spi-nor/spi-nor.c
@@ -1371,7 +1371,7 @@ static int spi_nor_write(struct mtd_info
 
 		write_enable(nor);
 		ret = nor->write(nor, addr, page_remain, buf + i);
-		if (ret < 0)
+		if (ret <= 0)
 			goto write_err;
 		written = ret;
 
@@ -1380,13 +1380,6 @@ static int spi_nor_write(struct mtd_info
 			goto write_err;
 		*retlen += written;
 		i += written;
-		if (written != page_remain) {
-			dev_err(nor->dev,
-				"While writing %zu bytes written %zd bytes\n",
-				page_remain, written);
-			ret = -EIO;
-			goto write_err;
-		}
 	}
 
 write_err: