linux-kernel - [PATCH v7 09/10] mtd: spi-nor: add read loop

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Message-Id: <1462494716-95312-10-git-send-email-computersforpeace@gmail.com>
Date:	Thu,  5 May 2016 17:31:55 -0700
From:	Brian Norris <computersforpeace@...il.com>
To:	<linux-mtd@...ts.infradead.org>
Cc:	Heiner Kallweit <hkallweit1@...il.com>,
	Brian Norris <computersforpeace@...il.com>,
	Han Xu <han.xu@....com>, Michal Suchanek <hramrach@...il.com>,
	Boris Brezillon <boris.brezillon@...e-electrons.com>,
	Javier Martinez Canillas <javier@....samsung.com>,
	Rafal Milecki <zajec5@...il.com>,
	Jagan Teki <jteki@...nedev.com>,
	"Andrew F. Davis" <afd@...com>,
	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	Gabor Juhos <juhosg@...nwrt.org>,
	Bean Huo <beanhuo@...ron.com>, linux-kernel@...r.kernel.org,
	Bayi Cheng <bayi.cheng@...iatek.com>,
	Joachim Eastwood <manabian@...il.com>,
	Cyrille Pitchen <cyrille.pitchen@...el.com>
Subject: [PATCH v7 09/10] mtd: spi-nor: add read loop

From: Michal Suchanek <hramrach@...il.com>

mtdblock and ubi do not handle the situation when read returns less data
than requested. Loop in spi-nor until buffer is filled or an error is
returned.

Signed-off-by: Michal Suchanek <hramrach@...il.com>
Signed-off-by: Brian Norris <computersforpeace@...il.com>
---
v6 -> v7:
 * no change

 drivers/mtd/spi-nor/spi-nor.c | 25 +++++++++++++++++++------
 1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
index ff96e1b54384..a78adcda1b85 100644
--- a/drivers/mtd/spi-nor/spi-nor.c
+++ b/drivers/mtd/spi-nor/spi-nor.c
@@ -1030,14 +1030,27 @@ static int spi_nor_read(struct mtd_info *mtd, loff_t from, size_t len,
 	if (ret)
 		return ret;
 
-	ret = nor->read(nor, from, len, buf);
+	while (len) {
+		ret = nor->read(nor, from, len, buf);
+		if (ret == 0) {
+			/* We shouldn't see 0-length reads */
+			ret = -EIO;
+			goto read_err;
+		}
+		if (ret < 0)
+			goto read_err;
 
-	spi_nor_unlock_and_unprep(nor, SPI_NOR_OPS_READ);
-	if (ret < 0)
-		return ret;
+		WARN_ON(ret > len);
+		*retlen += ret;
+		buf += ret;
+		from += ret;
+		len -= ret;
+	}
+	ret = 0;
 
-	*retlen += ret;
-	return 0;
+read_err:
+	spi_nor_unlock_and_unprep(nor, SPI_NOR_OPS_READ);
+	return ret;
 }
 
 static int sst_write(struct mtd_info *mtd, loff_t to, size_t len,
-- 
2.8.0.rc3.226.g39d4020