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    Subject[PATCH AUTOSEL for 4.9 183/219] mtd: nand: fix interpretation of NAND_CMD_NONE in nand_command[_lp]()
    Date
    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 == 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 21c03086bb7f..a3e86e52640a 100644
    --- 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 *mtd, unsigned int command,
    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 *mtd, unsigned int command,
    */
    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_info *mtd, unsigned int command,
    }

    /* 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_info *mtd, unsigned int command,
    */
    switch (command) {

    + case NAND_CMD_NONE:
    case NAND_CMD_CACHEDPROG:
    case NAND_CMD_PAGEPROG:
    case NAND_CMD_ERASE1:
    --
    2.14.1
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