On Wed, Dec 02, 2015 at 10:38:20AM +0000, Michal Suchanek wrote:
> The spi-nor write loop assumes that what is passed to the hardware
> driver write() is what gets written.
>
> When write() writes less than page size at once data is dropped on the
> floor. Check the amount of data writen and exit if it does not match
> requested amount.
>
> Signed-off-by: Michal Suchanek <hramr...@gmail.com>
>
> ---
>
> - add warning when writing incomplete pages
> - refuse to continue writing when full page was not written
> ---
> drivers/mtd/spi-nor/spi-nor.c | 58
> +++++++++++++++++++------------------------
> 1 file changed, 25 insertions(+), 33 deletions(-)
>
> diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
> index 3d02803..115c123 100644
> --- a/drivers/mtd/spi-nor/spi-nor.c
> +++ b/drivers/mtd/spi-nor/spi-nor.c
> @@ -1005,8 +1005,8 @@ static int spi_nor_write(struct mtd_info *mtd, loff_t
> to, size_t len,
> size_t *retlen, const u_char *buf)
> {
> struct spi_nor *nor = mtd_to_spi_nor(mtd);
> - u32 page_offset, page_size, i;
> - int ret;
> + size_t page_offset, page_remain, i;
> + ssize_t ret;
>
> dev_dbg(nor->dev, "to 0x%08x, len %zd\n", (u32)to, len);
>
> @@ -1014,45 +1014,37 @@ static int spi_nor_write(struct mtd_info *mtd, loff_t
> to, size_t len,
> if (ret)
> return ret;
>
> - write_enable(nor);
> -
> - page_offset = to & (nor->page_size - 1);
> + for (i = 0; i < len; ) {
> + ssize_t written;
>
> - /* do all the bytes fit onto one page? */
> - if (page_offset + len <= nor->page_size) {
> - ret = nor->write(nor, to, len, buf);
> - if (ret < 0)
> - goto write_err;
> - *retlen += ret;
> - } else {
> + page_offset = to & (nor->page_size - 1);
> + WARN_ONCE(page_offset,
> + "Writing at offset %zu into a NOR page. Writing
> partial pages may decrease reliability and increase wear of NOR flash.",
> + page_offset);
> /* the size of data remaining on the first page */
> - page_size = nor->page_size - page_offset;
> - ret = nor->write(nor, to, page_size, buf);
> + page_remain = min_t(size_t,
> + nor->page_size - page_offset, len - i);
> +
> + write_enable(nor);
> + ret = nor->write(nor, to + i, page_remain, buf + i);
Previous implementation was trying to write nor->page_size byte data in
each loop, except the first and last loop, if possible. But this change
may write only (nor->page_size - page_offset) in each loop, for the
worst case, if page_offset equals nor->page_size -1, it writes byte by
byte.
> if (ret < 0)
> goto write_err;
> - *retlen += ret;
> -
> - /* write everything in nor->page_size chunks */
> - for (i = ret; i < len; ) {
> - page_size = len - i;
> - if (page_size > nor->page_size)
> - page_size = nor->page_size;
> -
> - ret = spi_nor_wait_till_ready(nor);
> - if (ret)
> - goto write_err;
> + written = ret;
>
> - write_enable(nor);
> -
> - ret = nor->write(nor, to + i, page_size, buf + i);
> - if (ret < 0)
> - goto write_err;
> - *retlen += ret;
> - i += ret;
> + ret = spi_nor_wait_till_ready(nor);
> + if (ret)
> + goto write_err;
> + *retlen += written;
> + i += written;
> + if (written != page_remain) {
> + dev_err(nor->dev,
> + "While writing %zu bytes written %zd bytes\n",
> + page_remain, written);
> + ret = -EIO;
> + goto write_err;
> }
> }
>
> - ret = spi_nor_wait_till_ready(nor);
> write_err:
> spi_nor_unlock_and_unprep(nor, SPI_NOR_OPS_WRITE);
> return ret;
> --
> 2.6.2
>
--
Best Regards,
Han "Allen" Xu
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