[PATCH 4.9 175/241] mtd: nand: fix interpretation of NAND_CMD_NONE in nand_command[_lp]()

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

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

From: Miquel Raynal <miquel.raynal@xxxxxxxxxxxxxxxxxx>


[ 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 == NAND_CMD_NONE.

Signed-off-by: Miquel Raynal <miquel.raynal@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/mtd/nand/nand_base.c |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -715,7 +715,8 @@ static void nand_command(struct mtd_info
 		chip->cmd_ctrl(mtd, readcmd, ctrl);
 		ctrl &= ~NAND_CTRL_CHANGE;
 	}
-	chip->cmd_ctrl(mtd, command, ctrl);
+	if (command != NAND_CMD_NONE)
+		chip->cmd_ctrl(mtd, command, ctrl);
 
 	/* Address cycle, when necessary */
 	ctrl = NAND_CTRL_ALE | NAND_CTRL_CHANGE;
@@ -744,6 +745,7 @@ static void nand_command(struct mtd_info
 	 */
 	switch (command) {
 
+	case NAND_CMD_NONE:
 	case NAND_CMD_PAGEPROG:
 	case NAND_CMD_ERASE1:
 	case NAND_CMD_ERASE2:
@@ -806,7 +808,9 @@ static void nand_command_lp(struct mtd_i
 	}
 
 	/* Command latch cycle */
-	chip->cmd_ctrl(mtd, command, NAND_NCE | NAND_CLE | NAND_CTRL_CHANGE);
+	if (command != NAND_CMD_NONE)
+		chip->cmd_ctrl(mtd, command,
+			       NAND_NCE | NAND_CLE | NAND_CTRL_CHANGE);
 
 	if (column != -1 || page_addr != -1) {
 		int ctrl = NAND_CTRL_CHANGE | NAND_NCE | NAND_ALE;
@@ -842,6 +846,7 @@ static void nand_command_lp(struct mtd_i
 	 */
 	switch (command) {
 
+	case NAND_CMD_NONE:
 	case NAND_CMD_CACHEDPROG:
 	case NAND_CMD_PAGEPROG:
 	case NAND_CMD_ERASE1: