[PATCH v2] mtd: nand: fix interpretation of NAND_CMD_NONE in nand_command[_lp]()

[Boris Brezillon]

On Wed,  8 Nov 2017 17:00:27 +0100
Miquel Raynal <miquel.raynal at free-electrons.com> wrote:

> 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.

Applied.

Thanks,

Boris

> 
> Signed-off-by: Miquel Raynal <miquel.raynal at free-electrons.com>
> ---
> 
> Hello,
> 
> Changes since v1:
>   - Commit message rewording.
>   - Added a case for NAND_CMD_NONE in the switch statement of each
>     function to avoid unnecesary wait.
> 
> Thanks,
> Miquèl
> 
> 
>  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 e48bf8260f54..074b67571bfc 100644
> --- a/drivers/mtd/nand/nand_base.c
> +++ b/drivers/mtd/nand/nand_base.c
> @@ -710,7 +710,8 @@ 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;
> @@ -738,6 +739,7 @@ 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:
> @@ -831,7 +833,9 @@ 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;
> @@ -866,6 +870,7 @@ 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: