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nand_util: drop trailing all-0xff pages if requested

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Add a flag to nand_read_skip_bad() such that if true, any trailing
pages in an eraseblock whose contents are entirely 0xff will be
dropped.

The implementation is via a new drop_ffs() function which is
based on the function of the same name from the ubiformat
utility by Artem Bityutskiy.

This is as-per the reccomendations of the UBI FAQ [1]

[1] http://www.linux-mtd.infradead.org/doc/ubi.html#L_flasher_algo

Signed-off-by: Ben Gardiner <bengardiner@nanometrics.ca>
CC: Artem Bityutskiy <dedekind1@gmail.com>
Acked-by: Detlev Zundel <dzu@denx.de>
CC: Scott Wood <scottwood@freescale.com>
Signed-off-by: Scott Wood <scottwood@freescale.com>
This commit is contained in:
Ben Gardiner 2011-06-14 16:35:06 -04:00 committed by Scott Wood
parent c135456ff5
commit 169d54d8b3
2 changed files with 38 additions and 3 deletions
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40
drivers/mtd/nand/nand_util.c
View File

@ -11,6 +11,9 @@
* nandwrite.c by Steven J. Hill (sjhill@realitydiluted.com)
* and Thomas Gleixner (tglx@linutronix.de)
*
* Copyright (C) 2008 Nokia Corporation: drop_ffs() function by
* Artem Bityutskiy <dedekind1@gmail.com> from mtd-utils
*
* See file CREDITS for list of people who contributed to this
* project.
*
@ -436,6 +439,29 @@ static int check_skip_len(nand_info_t *nand, loff_t offset, size_t length)
return ret;
}
#ifdef CONFIG_CMD_NAND_TRIMFFS
static size_t drop_ffs(const nand_info_t *nand, const u_char *buf,
const size_t *len)
{
size_t i, l = *len;
for (i = l - 1; i >= 0; i--)
if (buf[i] != 0xFF)
break;
/* The resulting length must be aligned to the minimum flash I/O size */
l = i + 1;
l = (l + nand->writesize - 1) / nand->writesize;
l *= nand->writesize;
/*
* since the input length may be unaligned, prevent access past the end
* of the buffer
*/
return min(l, *len);
}
#endif
/**
* nand_write_skip_bad:
*
@ -502,7 +528,7 @@ int nand_write_skip_bad(nand_info_t *nand, loff_t offset, size_t *length,
return -EINVAL;
}
if (!need_skip) {
if (!need_skip && !(flags & WITH_DROP_FFS)) {
rval = nand_write (nand, offset, length, buffer);
if (rval == 0)
return 0;
@ -515,7 +541,7 @@ int nand_write_skip_bad(nand_info_t *nand, loff_t offset, size_t *length,
while (left_to_write > 0) {
size_t block_offset = offset & (nand->erasesize - 1);
size_t write_size;
size_t write_size, truncated_write_size;
WATCHDOG_RESET ();
@ -561,7 +587,15 @@ int nand_write_skip_bad(nand_info_t *nand, loff_t offset, size_t *length,
else
#endif
{
rval = nand_write (nand, offset, &write_size, p_buffer);
truncated_write_size = write_size;
#ifdef CONFIG_CMD_NAND_TRIMFFS
if (flags & WITH_DROP_FFS)
truncated_write_size = drop_ffs(nand, p_buffer,
&write_size);
#endif
rval = nand_write(nand, offset, &truncated_write_size,
p_buffer);
offset += write_size;
p_buffer += write_size;
}

1
include/nand.h
View File

@ -118,6 +118,7 @@ int nand_read_skip_bad(nand_info_t *nand, loff_t offset, size_t *length,
#define WITH_YAFFS_OOB (1 << 0) /* whether write with yaffs format. This flag
* is a 'mode' meaning it cannot be mixed with
* other flags */
#define WITH_DROP_FFS (1 << 1) /* drop trailing all-0xff pages */
int nand_write_skip_bad(nand_info_t *nand, loff_t offset, size_t *length,
u_char *buffer, int flags);