Re: [PATCH 2/3] MTD: spi-nor: check for short writes in spi_nor_write.

Brian Norris
2015-05-20T23:38:46Z

+ linux-spi, Mark

On Thu, Apr 30, 2015 at 03:38:50PM +0200, Michal Suchanek wrote:
> My SPI controller driver does not support DMA so writes are truncated to
> FIFO size.

Which SPI master driver?

> Check the amount of data actually written by the driver.

I'm not sure if we should just reactively use the retlen, or if we
should be communicating such a limitation via the SPI API. Thoughts?

Brian

> Signed-off-by: Michal Suchanek <hramrach@gmail.com>
> ---
> drivers/mtd/spi-nor/spi-nor.c | 42 +++++++++++++++++-------------------------
> 1 file changed, 17 insertions(+), 25 deletions(-)
>
> diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
> index 14a5d23..75904b5 100644
> --- a/drivers/mtd/spi-nor/spi-nor.c
> +++ b/drivers/mtd/spi-nor/spi-nor.c
> @@ -807,7 +807,7 @@ 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;
> + u32 page_offset, page_remainder, page_size, i;
> int ret;
>
> dev_dbg(nor->dev, "to 0x%08x, len %zd\n", (u32)to, len);
> @@ -816,36 +816,28 @@ 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);
> -
> - /* do all the bytes fit onto one page? */
> - if (page_offset + len <= nor->page_size) {
> - nor->write(nor, to, len, retlen, buf);
> - } else {
> - /* the size of data remaining on the first page */
> - page_size = nor->page_size - page_offset;
> - nor->write(nor, to, page_size, retlen, buf);
> + /* write everything in nor->page_size chunks */
> + /* check the size of data actually written */
> + for (i = 0; i < len; i += *retlen) {
> + page_size = len - i;
> + page_offset = (to + i) & (nor->page_size - 1);
> + page_remainder = nor->page_size - page_offset;
> + if (page_size > nor->page_size)
> + page_size = nor->page_size;
> + if (page_remainder && (page_size > page_remainder))
> + page_size = page_remainder;
>
> - /* write everything in nor->page_size chunks */
> - for (i = page_size; i < len; i += page_size) {
> - 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;
> + write_enable(nor);
>
> - write_enable(nor);
> + nor->write(nor, to + i, page_size, retlen, buf + i);
>
> - nor->write(nor, to + i, page_size, retlen, buf + i);
> - }
> + ret = spi_nor_wait_till_ready(nor);
> + if (ret)
> + goto write_err;
> }
>
> - ret = spi_nor_wait_till_ready(nor);
> write_err:
> + *retlen = i;
> spi_nor_unlock_and_unprep(nor, SPI_NOR_OPS_WRITE);
> return ret;
> }