[U-Boot] [PATCH 5/5] mtd/nand: workaround for Freescale FCM to support 4k pagesize Nand chip

[Marek Vasut]

> 于 2011年12月09日 00:37, Marek Vasut 写道:
> >> Freescale FCM controller has a 2K size limitation of buffer RAM. In
> >> order to support the Nand flash chip whose page size is larger than 2K
> >> bytes, we read/write 2k data repeatedly by issuing FIR_OP_RB/FIR_OP_WB
> >> and save them to a large buffer.
> >> 
> >> Signed-off-by: Shengzhou Liu<Shengzhou.Liu at freescale.com>
> >> Signed-off-by: Liu Shuo<b35362 at freescale.com>
> >> ---
> >> 
> >>   drivers/mtd/nand/fsl_elbc_nand.c |  279
> >> 
> >> +++++++++++++++++++++++++++++++++---- 1 files changed, 248
> >> insertions(+), 31 deletions(-)
> >> 
> >> diff --git a/drivers/mtd/nand/fsl_elbc_nand.c
> >> b/drivers/mtd/nand/fsl_elbc_nand.c index 52362b1..3983c8c 100644
> >> --- a/drivers/mtd/nand/fsl_elbc_nand.c
> >> +++ b/drivers/mtd/nand/fsl_elbc_nand.c
> >> @@ -64,7 +64,6 @@ struct fsl_elbc_mtd {
> >> 
> >>   	struct device *dev;
> >>   	int bank;               /* Chip select bank number           */
> >>   	u8 __iomem *vbase;      /* Chip select base virtual address  */
> >> 
> >> -	int page_size;          /* NAND page size (0=512, 1=2048)    */
> >> 
> >>   	unsigned int fmr;       /* FCM Flash Mode Register value     */
> >>   
> >>   };
> >> 
> >> @@ -85,6 +84,8 @@ struct fsl_elbc_ctrl {
> >> 
> >>   	unsigned int mdr;        /* UPM/FCM Data Register value           */
> >>   	unsigned int use_mdr;    /* Non zero if the MDR is to be set      */
> >>   	unsigned int oob;        /* Non zero if operating on OOB data     */
> >> 
> >> +	char *buffer;            /* just used when pagesize is greater    */
> > 
> > Start sentence with capital letter
> > 
> >> +				 /* than FCM RAM 2K limitation		  */
> >> 
> >>   };
> >>   
> >>   /* These map to the positions used by the FCM hardware ECC generator
> >>   */
> >> 
> >> @@ -159,6 +160,44 @@ static struct nand_bbt_descr bbt_mirror_descr = {
> >> 
> >>   	.pattern = mirror_pattern,
> >>   
> >>   };
> >> 
> >> +static void io_to_buffer(struct mtd_info *mtd, int subpage, int oob)
> >> +{
> >> +	struct nand_chip *chip = mtd->priv;
> >> +	struct fsl_elbc_mtd *priv = chip->priv;
> >> +	struct fsl_elbc_ctrl *ctrl = priv->ctrl;
> >> +	void *src, *dst;
> >> +	int len = (oob ? 64 : 2048);
> > 
> > No parenthesis ...
> > 
> >> +
> >> +	/* for emulating 4096+ bytes NAND using 2048-byte FCM RAM */
> >> +	if (oob)
> >> +		dst = ctrl->buffer + mtd->writesize + subpage * 64;
> >> +	else
> >> +		dst = ctrl->buffer + subpage * 2048;
> > 
> > subpage * len ?
> 
> dst = ctrl->buffer + (oob ? mtd->writesize : 0) + subpage * len ?
> Is this important ? I think it is ok.

dst = ctrl->buffer + subpage * len;

if (oob)
	dst += mtd->writesize;

it's important, this code looks like mess. You introduce len and don't use it 
anywhere then ?

M