driver/mtd/ifc: Read Status while programming NAND flash

as per controller description,
  "While programming a NAND flash, status read should never skipped.
   Because it may happen that a new command is issued to the NAND Flash,
   even when the device has not yet finished processing the previous request.
   This may result in unpredictable behaviour."

IFC controller never polls for R/B signal after command send. It just return
control to software. This behaviour may not occur with NAND flash access.
because new commands are sent after polling R/B signal. But it may happen
in scenario where GPCM-ASIC and NAND flash device are working simultaneously.

Update the controller driver to take care of this requirement

Signed-off-by: Prabhakar Kushwaha <prabhakar@freescale.com>
---
 drivers/mtd/nand/fsl_ifc_nand.c |   34 ++++++++++++++++++++++++----------
 1 file changed, 24 insertions(+), 10 deletions(-)

Hi Artem,

This patch is present in upstream review list from a long time.
There are no review comments.

So, I request you to pick this patch for linux-mtd.git repository.

Regards,
Prabhakar


On 10/03/2013 11:36 AM, Prabhakar Kushwaha wrote:
> as per controller description,
>    "While programming a NAND flash, status read should never skipped.
>     Because it may happen that a new command is issued to the NAND Flash,
>     even when the device has not yet finished processing the previous request.
>     This may result in unpredictable behaviour."
>
> IFC controller never polls for R/B signal after command send. It just return
> control to software. This behaviour may not occur with NAND flash access.
> because new commands are sent after polling R/B signal. But it may happen
> in scenario where GPCM-ASIC and NAND flash device are working simultaneously.
>
> Update the controller driver to take care of this requirement
>
> Signed-off-by: Prabhakar Kushwaha <prabhakar@freescale.com>
> ---
>   drivers/mtd/nand/fsl_ifc_nand.c |   34 ++++++++++++++++++++++++----------
>   1 file changed, 24 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/mtd/nand/fsl_ifc_nand.c b/drivers/mtd/nand/fsl_ifc_nand.c
> index a14885b..eb150f1 100644
> --- a/drivers/mtd/nand/fsl_ifc_nand.c
> +++ b/drivers/mtd/nand/fsl_ifc_nand.c
> @@ -504,20 +504,29 @@ static void fsl_ifc_cmdfunc(struct mtd_info *mtd, unsigned int command,
>   		if (mtd->writesize > 512) {
>   			nand_fcr0 =
>   				(NAND_CMD_SEQIN << IFC_NAND_FCR0_CMD0_SHIFT) |
> -				(NAND_CMD_PAGEPROG << IFC_NAND_FCR0_CMD1_SHIFT);
> +				(NAND_CMD_STATUS << IFC_NAND_FCR0_CMD1_SHIFT) |
> +				(NAND_CMD_PAGEPROG << IFC_NAND_FCR0_CMD2_SHIFT);
>   
>   			iowrite32be(
> -				(IFC_FIR_OP_CW0 << IFC_NAND_FIR0_OP0_SHIFT) |
> -				(IFC_FIR_OP_CA0 << IFC_NAND_FIR0_OP1_SHIFT) |
> -				(IFC_FIR_OP_RA0 << IFC_NAND_FIR0_OP2_SHIFT) |
> -				(IFC_FIR_OP_WBCD << IFC_NAND_FIR0_OP3_SHIFT) |
> -				(IFC_FIR_OP_CW1 << IFC_NAND_FIR0_OP4_SHIFT),
> -				&ifc->ifc_nand.nand_fir0);
> +				 (IFC_FIR_OP_CW0 << IFC_NAND_FIR0_OP0_SHIFT) |
> +				 (IFC_FIR_OP_CA0 << IFC_NAND_FIR0_OP1_SHIFT) |
> +				 (IFC_FIR_OP_RA0 << IFC_NAND_FIR0_OP2_SHIFT) |
> +				 (IFC_FIR_OP_WBCD  << IFC_NAND_FIR0_OP3_SHIFT) |
> +				 (IFC_FIR_OP_CMD2 << IFC_NAND_FIR0_OP4_SHIFT),
> +				 &ifc->ifc_nand.nand_fir0);
> +			iowrite32be(
> +				 (IFC_FIR_OP_CW1 << IFC_NAND_FIR1_OP5_SHIFT) |
> +				 (IFC_FIR_OP_RDSTAT <<
> +					IFC_NAND_FIR1_OP6_SHIFT) |
> +				 (IFC_FIR_OP_NOP << IFC_NAND_FIR1_OP7_SHIFT),
> +				 &ifc->ifc_nand.nand_fir1);
>   		} else {
>   			nand_fcr0 = ((NAND_CMD_PAGEPROG <<
>   					IFC_NAND_FCR0_CMD1_SHIFT) |
>   				    (NAND_CMD_SEQIN <<
> -					IFC_NAND_FCR0_CMD2_SHIFT));
> +					IFC_NAND_FCR0_CMD2_SHIFT) |
> +				    (NAND_CMD_STATUS <<
> +					IFC_NAND_FCR0_CMD3_SHIFT));
>   
>   			iowrite32be(
>   				(IFC_FIR_OP_CW0 << IFC_NAND_FIR0_OP0_SHIFT) |
> @@ -526,8 +535,13 @@ static void fsl_ifc_cmdfunc(struct mtd_info *mtd, unsigned int command,
>   				(IFC_FIR_OP_RA0 << IFC_NAND_FIR0_OP3_SHIFT) |
>   				(IFC_FIR_OP_WBCD << IFC_NAND_FIR0_OP4_SHIFT),
>   				&ifc->ifc_nand.nand_fir0);
> -			iowrite32be(IFC_FIR_OP_CW1 << IFC_NAND_FIR1_OP5_SHIFT,
> -				    &ifc->ifc_nand.nand_fir1);
> +			iowrite32be(
> +				 (IFC_FIR_OP_CMD1 << IFC_NAND_FIR1_OP5_SHIFT) |
> +				 (IFC_FIR_OP_CW3 << IFC_NAND_FIR1_OP6_SHIFT) |
> +				 (IFC_FIR_OP_RDSTAT <<
> +					IFC_NAND_FIR1_OP7_SHIFT) |
> +				 (IFC_FIR_OP_NOP << IFC_NAND_FIR1_OP8_SHIFT),
> +				  &ifc->ifc_nand.nand_fir1);
>   
>   			if (column >= mtd->writesize)
>   				nand_fcr0 |=

On Thu, Oct 03, 2013 at 11:36:41AM +0530, Prabhakar Kushwaha wrote:
> as per controller description,
>   "While programming a NAND flash, status read should never skipped.
>    Because it may happen that a new command is issued to the NAND Flash,
>    even when the device has not yet finished processing the previous request.
>    This may result in unpredictable behaviour."
> 
> IFC controller never polls for R/B signal after command send. It just return
> control to software. This behaviour may not occur with NAND flash access.
> because new commands are sent after polling R/B signal. But it may happen
> in scenario where GPCM-ASIC and NAND flash device are working simultaneously.
> 
> Update the controller driver to take care of this requirement
> 
> Signed-off-by: Prabhakar Kushwaha <prabhakar@freescale.com>

Pushed to l2-mtd.git. Thanks!

Brian