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From:   Ben Hutchings <ben@decadent.org.uk>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
CC:     akpm@linux-foundation.org,
        "Boris Brezillon" <boris.brezillon@free-electrons.com>,
        "Brent Taylor" <motobud@gmail.com>
Date:   Sun, 11 Feb 2018 04:20:06 +0000
Message-ID: <lsq.1518322806.274990324@decadent.org.uk>
Subject: [PATCH 3.2 23/79] mtd: nand: Fix writing mtdoops to nand flash.
In-Reply-To: <lsq.1518322802.943358572@decadent.org.uk>
Sender: linux-kernel-owner@vger.kernel.org
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3.2.99-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Brent Taylor <motobud@gmail.com>

commit 30863e38ebeb500a31cecee8096fb5002677dd9b upstream.

When mtdoops calls mtd_panic_write(), it eventually calls
panic_nand_write() in nand_base.c. In order to properly wait for the
nand chip to be ready in panic_nand_wait(), the chip must first be
selected.

When using the atmel nand flash controller, a panic would occur due to
a NULL pointer exception.

Fixes: 2af7c6539931 ("mtd: Add panic_write for NAND flashes")
Signed-off-by: Brent Taylor <motobud@gmail.com>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 drivers/mtd/nand/nand_base.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -2290,6 +2290,7 @@ static int panic_nand_write(struct mtd_i
 			    size_t *retlen, const uint8_t *buf)
 {
 	struct nand_chip *chip = mtd->priv;
+	int chipnr = (int)(to >> chip->chip_shift);
 	struct mtd_oob_ops ops;
 	int ret;
 
@@ -2299,12 +2300,14 @@ static int panic_nand_write(struct mtd_i
 	if (!len)
 		return 0;
 
-	/* Wait for the device to get ready */
-	panic_nand_wait(mtd, chip, 400);
-
 	/* Grab the device */
 	panic_nand_get_device(chip, mtd, FL_WRITING);
 
+	chip->select_chip(mtd, chipnr);
+
+	/* Wait for the device to get ready */
+	panic_nand_wait(mtd, chip, 400);
+
 	ops.len = len;
 	ops.datbuf = (uint8_t *)buf;
 	ops.oobbuf = NULL;