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From:   Sasha Levin <Alexander.Levin@microsoft.com>
To:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "stable@vger.kernel.org" <stable@vger.kernel.org>
CC:     Miquel Raynal <miquel.raynal@free-electrons.com>,
        Boris Brezillon <boris.brezillon@free-electrons.com>,
        Sasha Levin <Alexander.Levin@microsoft.com>
Subject: [PATCH AUTOSEL for 4.4 092/115] mtd: nand: fix interpretation of
 NAND_CMD_NONE in nand_command[_lp]()
Thread-Topic: [PATCH AUTOSEL for 4.4 092/115] mtd: nand: fix interpretation of
 NAND_CMD_NONE in nand_command[_lp]()
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Date:   Sat, 3 Mar 2018 22:31:44 +0000
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From: Miquel Raynal <miquel.raynal@free-electrons.com>

[ Upstream commit df467899da0b71465760b4e35127bce837244eee ]

Some drivers (like nand_hynix.c) call ->cmdfunc() with NAND_CMD_NONE
and a column address and expect the controller to only send address
cycles. Right now, the default ->cmdfunc() implementations provided by
the core do not filter out the command cycle in this case and forwards
the request to the controller driver through the ->cmd_ctrl() method.
The thing is, NAND controller drivers can get this wrong and send a
command cycle with a NAND_CMD_NONE opcode and since NAND_CMD_NONE is
-1, and the command field is usually casted to an u8, we end up sending
the 0xFF command which is actually a RESET operation.

Add conditions in nand_command[_lp]() functions to sending the initial
command cycle when command =3D=3D NAND_CMD_NONE.

Signed-off-by: Miquel Raynal <miquel.raynal@free-electrons.com>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
 drivers/mtd/nand/nand_base.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index 27864c0863ef..8406f346b0be 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -626,7 +626,8 @@ static void nand_command(struct mtd_info *mtd, unsigned=
 int command,
 		chip->cmd_ctrl(mtd, readcmd, ctrl);
 		ctrl &=3D ~NAND_CTRL_CHANGE;
 	}
-	chip->cmd_ctrl(mtd, command, ctrl);
+	if (command !=3D NAND_CMD_NONE)
+		chip->cmd_ctrl(mtd, command, ctrl);
=20
 	/* Address cycle, when necessary */
 	ctrl =3D NAND_CTRL_ALE | NAND_CTRL_CHANGE;
@@ -655,6 +656,7 @@ static void nand_command(struct mtd_info *mtd, unsigned=
 int command,
 	 */
 	switch (command) {
=20
+	case NAND_CMD_NONE:
 	case NAND_CMD_PAGEPROG:
 	case NAND_CMD_ERASE1:
 	case NAND_CMD_ERASE2:
@@ -717,7 +719,9 @@ static void nand_command_lp(struct mtd_info *mtd, unsig=
ned int command,
 	}
=20
 	/* Command latch cycle */
-	chip->cmd_ctrl(mtd, command, NAND_NCE | NAND_CLE | NAND_CTRL_CHANGE);
+	if (command !=3D NAND_CMD_NONE)
+		chip->cmd_ctrl(mtd, command,
+			       NAND_NCE | NAND_CLE | NAND_CTRL_CHANGE);
=20
 	if (column !=3D -1 || page_addr !=3D -1) {
 		int ctrl =3D NAND_CTRL_CHANGE | NAND_NCE | NAND_ALE;
@@ -750,6 +754,7 @@ static void nand_command_lp(struct mtd_info *mtd, unsig=
ned int command,
 	 */
 	switch (command) {
=20
+	case NAND_CMD_NONE:
 	case NAND_CMD_CACHEDPROG:
 	case NAND_CMD_PAGEPROG:
 	case NAND_CMD_ERASE1:
--=20
2.14.1