[PATCH v5 4/5] mtd: nand: Allocate extra buffers needed for on-die ECC controller.

[Gerhard Sittig]

On Mon, 2014-04-14 at 13:35 -0600, David Mosberger wrote:
> 
> To avoid unnecessary rewrites, it is necessary to count the number of
> actual bitflips that occurred when the NAND_STATUS_REWRITE bit is set.
> This patch introduces the extra buffers needed to implement that
> counting.  The actual counting is in the next patch.

I'd suggest to s/the next patch/a subsequent patch/ -- the order
of commits in the mainline repo need not strictly follow
arbitrary submission sequences

> --- a/drivers/mtd/nand/nand_base.c
> +++ b/drivers/mtd/nand/nand_base.c
> @@ -3939,13 +3939,24 @@ int nand_scan_tail(struct mtd_info *mtd)
>  			!(chip->bbt_options & NAND_BBT_USE_FLASH));
>  
>  	if (!(chip->options & NAND_OWN_BUFFERS)) {
> +		size_t on_die_bufsz = 0;
> +
> +		if (chip->ecc.mode == NAND_ECC_HW_ON_DIE)
> +			on_die_bufsz = 2*(mtd->writesize + mtd->oobsize);
> +
>  		nbuf = kzalloc(sizeof(*nbuf) + mtd->writesize
> -				+ mtd->oobsize * 3, GFP_KERNEL);
> +				+ mtd->oobsize * 3 + on_die_bufsz, GFP_KERNEL);
>  		if (!nbuf)
>  			return -ENOMEM;
>  		nbuf->ecccalc = (uint8_t *)(nbuf + 1);
>  		nbuf->ecccode = nbuf->ecccalc + mtd->oobsize;
>  		nbuf->databuf = nbuf->ecccode + mtd->oobsize;
> +		if (chip->ecc.mode == NAND_ECC_HW_ON_DIE) {
> +			nbuf->chkbuf = (nbuf->databuf + mtd->writesize
> +					+ mtd->oobsize);
> +			nbuf->rawbuf = (nbuf->chkbuf + mtd->writesize
> +					+ mtd->oobsize);
> +		}
>  
>  		chip->buffers = nbuf;
>  	} else {

you introduce the 'on_die_bufsz' variable, can you use it (under
a more appropriate name then) to first determine the required
amount of memory and then have a kzalloc() call with a size spec
that is not as complex as the current implementation?

independent from this optional style improvement, you should
fixup the whitespace issues around operators, and remove the
unnecessary parentheses; having the "writesize + oobsize" in
another variable might help eliminate more duplication and trim
line length, and better reflect how the size calculation and the
pointer calculation match each other


virtually yours
Gerhard Sittig
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