From 30863e38ebeb500a31cecee8096fb5002677dd9b Mon Sep 17 00:00:00 2001
From: Brent Taylor <motobud@gmail.com>
Date: Mon, 30 Oct 2017 22:32:45 -0500
Subject: [PATCH] mtd: nand: Fix writing mtdoops to nand flash.
Git-commit: 30863e38ebeb500a31cecee8096fb5002677dd9b
Patch-mainline: v4.15-rc1
References: bsc#1051510

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")
Cc: <stable@vger.kernel.org>
Signed-off-by: Brent Taylor <motobud@gmail.com>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/mtd/nand/nand_base.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index 4c867115c53b..e48bf8260f54 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -2799,15 +2799,18 @@ static int panic_nand_write(struct mtd_info *mtd, loff_t to, size_t len,
 			    size_t *retlen, const uint8_t *buf)
 {
 	struct nand_chip *chip = mtd_to_nand(mtd);
+	int chipnr = (int)(to >> chip->chip_shift);
 	struct mtd_oob_ops ops;
 	int ret;
 
-	/* 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);
+
 	memset(&ops, 0, sizeof(ops));
 	ops.len = len;
 	ops.datbuf = (uint8_t *)buf;
-- 
2.16.4