A question about nand_read()
ext-adrian.hunter at nokia.com
Mon Nov 24 04:53:05 EST 2008
Patrick Turley wrote:
> No love? Is my question too n00bish?
People are busy.
You should test this yourself, and if you can make it go wrong
submit a patch.
I glanced at the code and it looks OK because struct nand_chip
is always initialised to zero and chip->ops.mode is never assigned.
> On Tue, 18 Nov 2008 18:43:55 -0600, Patrick Turley
> <patrick.turley at freescale.com> wrote:
>> My tree is up-to-date as I'm writing this message.
>> I'm looking at nand_read() in nand_base.c, starting at line 1175, quoted
>> here for your convenience:
>> static int nand_read(struct mtd_info *mtd, loff_t from, size_t len,
>> size_t *retlen, uint8_t *buf)
>> struct nand_chip *chip = mtd->priv;
>> int ret;
>> /* Do not allow reads past end of device */
>> if ((from + len) > mtd->size)
>> return -EINVAL;
>> if (!len)
>> return 0;
>> nand_get_device(chip, mtd, FL_READING);
>> chip->ops.len = len;
>> chip->ops.datbuf = buf;
>> chip->ops.oobbuf = NULL;
>> ret = nand_do_read_ops(mtd, from, &chip->ops);
>> *retlen = chip->ops.retlen;
>> return ret;
>> In particular, I'm looking at the preparation to call nand_do_read_ops(),
>> where the chip->ops structure is filled in.
>> Here's a small excerpt from nand_do_read_ops() that concerns me:
>> /* Now read the page into the buffer */
>> if (unlikely(ops->mode == MTD_OOB_RAW))
>> ret = chip->ecc.read_page_raw(mtd, chip, bufpoi);
>> else if (!aligned && NAND_SUBPAGE_READ(chip) && !oob)
>> ret = chip->ecc.read_subpage(mtd, chip, col, bytes, bufpoi);
>> ret = chip->ecc.read_page(mtd, chip, bufpoi);
>> if (ret < 0)
>> Note that nand_do_read_ops() will look at the mode field of the ops
>> structure, but this field hasn't been set by nand_read().
>> On the face of it, this looks like a bug. Is there something I don't know
>> that makes this not a bug? For example, is the value in the mode field
>> intended to persist across operations?
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