linux-kernel - [PATCH v2] mtd: nand: Fix writing mtdoops to nand flash.

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Date:   Mon, 30 Oct 2017 22:32:45 -0500
From:   motobud@...il.com
To:     boris.brezillon@...e-electrons.com
Cc:     Brent Taylor <motobud@...il.com>,
        Richard Weinberger <richard@....at>,
        David Woodhouse <dwmw2@...radead.org>,
        Brian Norris <computersforpeace@...il.com>,
        Marek Vasut <marek.vasut@...il.com>,
        Cyrille Pitchen <cyrille.pitchen@...ev4u.fr>,
        linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2] mtd: nand: Fix writing mtdoops to nand flash.

From: Brent Taylor <motobud@...il.com>

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.

Signed-off-by: Brent Taylor <motobud@...il.com>
---
Changes in v2:
  - drop deselecting the chip
  - move select_chip and panic_nand_wait after panic_nand_get_device

 drivers/mtd/nand/nand_base.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index 12edaae17d81..2093667e2bcb 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -2802,12 +2802,16 @@ static int panic_nand_write(struct mtd_info *mtd, loff_t to, size_t len,
 	struct mtd_oob_ops ops;
 	int ret;
 
-	/* Wait for the device to get ready */
-	panic_nand_wait(mtd, chip, 400);
+	int chipnr = (int)(to >> chip->chip_shift);
 
 	/* 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;
-- 
2.14.2