linux-kernel - [PATCH 4.19 088/103] mtd: devices: fix mchp23k256 read and write

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Date:   Wed, 22 Jan 2020 10:29:44 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Angelo Dureghello <angelo.dureghello@...esys.com>,
        Andrew Lunn <andrew@...n.ch>,
        Miquel Raynal <miquel.raynal@...tlin.com>
Subject: [PATCH 4.19 088/103] mtd: devices: fix mchp23k256 read and write

From: Angelo Dureghello <angelo.dureghello@...esys.com>

commit 14f89e088155314d311e4d4dd9f2b4ccaeef92b2 upstream.

Due to the use of sizeof(), command size set for the spi transfer
was wrong. Driver was sending and receiving always 1 byte less
and especially on write, it was hanging.

echo -n -e "\\x1\\x2\\x3\\x4" > /dev/mtd1

And read part too now works as expected.

hexdump -C -n16 /dev/mtd1
00000000  01 02 03 04 ab f3 ad c2  ab e3 f4 36 dd 38 04 15
00000010

Fixes: 4379075a870b ("mtd: mchp23k256: Add support for mchp23lcv1024")
Signed-off-by: Angelo Dureghello <angelo.dureghello@...esys.com>
Reviewed-by: Andrew Lunn <andrew@...n.ch>
Signed-off-by: Miquel Raynal <miquel.raynal@...tlin.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/mtd/devices/mchp23k256.c |   20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

--- a/drivers/mtd/devices/mchp23k256.c
+++ b/drivers/mtd/devices/mchp23k256.c
@@ -68,15 +68,17 @@ static int mchp23k256_write(struct mtd_i
 	struct spi_transfer transfer[2] = {};
 	struct spi_message message;
 	unsigned char command[MAX_CMD_SIZE];
-	int ret;
+	int ret, cmd_len;
 
 	spi_message_init(&message);
 
+	cmd_len = mchp23k256_cmdsz(flash);
+
 	command[0] = MCHP23K256_CMD_WRITE;
 	mchp23k256_addr2cmd(flash, to, command);
 
 	transfer[0].tx_buf = command;
-	transfer[0].len = mchp23k256_cmdsz(flash);
+	transfer[0].len = cmd_len;
 	spi_message_add_tail(&transfer[0], &message);
 
 	transfer[1].tx_buf = buf;
@@ -92,8 +94,8 @@ static int mchp23k256_write(struct mtd_i
 	if (ret)
 		return ret;
 
-	if (retlen && message.actual_length > sizeof(command))
-		*retlen += message.actual_length - sizeof(command);
+	if (retlen && message.actual_length > cmd_len)
+		*retlen += message.actual_length - cmd_len;
 
 	return 0;
 }
@@ -105,16 +107,18 @@ static int mchp23k256_read(struct mtd_in
 	struct spi_transfer transfer[2] = {};
 	struct spi_message message;
 	unsigned char command[MAX_CMD_SIZE];
-	int ret;
+	int ret, cmd_len;
 
 	spi_message_init(&message);
 
+	cmd_len = mchp23k256_cmdsz(flash);
+
 	memset(&transfer, 0, sizeof(transfer));
 	command[0] = MCHP23K256_CMD_READ;
 	mchp23k256_addr2cmd(flash, from, command);
 
 	transfer[0].tx_buf = command;
-	transfer[0].len = mchp23k256_cmdsz(flash);
+	transfer[0].len = cmd_len;
 	spi_message_add_tail(&transfer[0], &message);
 
 	transfer[1].rx_buf = buf;
@@ -130,8 +134,8 @@ static int mchp23k256_read(struct mtd_in
 	if (ret)
 		return ret;
 
-	if (retlen && message.actual_length > sizeof(command))
-		*retlen += message.actual_length - sizeof(command);
+	if (retlen && message.actual_length > cmd_len)
+		*retlen += message.actual_length - cmd_len;
 
 	return 0;
 }