Re: [PATCH 1/2] mtd/nand:Fix wrong address read in is_blank()
From: Scott Wood <hidden>
Date: 2012-01-03 20:24:13
On 12/28/2011 10:59 PM, Prabhakar Kushwaha wrote:
quoted hunk ↗ jump to hunk
IFC NAND Machine calculates ECC on 512byte sector. Same is taken care in fsl_ifc_run_command() while ECC status verification. Here buffer number is calculated assuming 512byte sector and same is passed to is_blank. However in is_blank() buffer address is calculated using mdt->writesize which is wrong. It should be calculated on basis of ecc sector size. Also, in fsl_ifc_run_command() bufferpage is calculated on the basis of ecc sector size instead of hard coded value. Signed-off-by: Poonam Aggrwal <redacted> Signed-off-by: Prabhakar Kushwaha <redacted> --- git://git.kernel.org/pub/scm/linux/kernel/git/galak/powerpc.git (branch next) Tested on P1010RDB drivers/mtd/nand/fsl_ifc_nand.c | 6 ++++-- 1 files changed, 4 insertions(+), 2 deletions(-)diff --git a/drivers/mtd/nand/fsl_ifc_nand.c b/drivers/mtd/nand/fsl_ifc_nand.c index 8475b88..2df7206 100644 --- a/drivers/mtd/nand/fsl_ifc_nand.c +++ b/drivers/mtd/nand/fsl_ifc_nand.c@@ -191,7 +191,9 @@ static int is_blank(struct mtd_info *mtd, unsigned int bufnum) { struct nand_chip *chip = mtd->priv; struct fsl_ifc_mtd *priv = chip->priv; - u8 __iomem *addr = priv->vbase + bufnum * (mtd->writesize * 2); + int bufperpage = mtd->writesize / chip->ecc.size; + u8 __iomem *addr = priv->vbase + bufnum / bufperpage + * (mtd->writesize * 2); u32 __iomem *mainarea = (u32 *)addr; u8 __iomem *oob = addr + mtd->writesize; int i;
This function should only be checking one ECC block, not the entire page. The caller is responsible for passing in the appropriate buffer numbers. I think what the current code needs is for (mtd->writesize * 2) to be replaced with chip->ecc.size, and for the calling code to multiply the starting bufnum by two.
quoted hunk ↗ jump to hunk
@@ -273,7 +275,7 @@ static void fsl_ifc_run_command(struct mtd_info *mtd) dev_err(priv->dev, "NAND Flash Write Protect Error\n"); if (nctrl->eccread) { - int bufperpage = mtd->writesize / 512; + int bufperpage = mtd->writesize / chip->ecc.size; int bufnum = (nctrl->page & priv->bufnum_mask) * bufperpage; int bufnum_end = bufnum + bufperpage - 1;
Currently this driver always sets chip->ecc.size to 512. If we want to support other ECC block sizes that future versions of IFC may have, can we calculate bufperpage during chip init (similar to bufnum_mask) to avoid the runtime division? It's probably not huge overhead compared to everything else we do per NAND page transfer, but still... -Scott