From mboxrd@z Thu Jan 1 00:00:00 1970 From: Han Xu Subject: Re: [PATCH v6 06/10] mtd: spi-nor: simplify write loop Date: Tue, 15 Dec 2015 14:22:17 -0600 Message-ID: <20151215202216.GA11742@chopperman.am.freescale.net> References: <2236d87ad516f118f58eb5df232d441f970c4499.1449052427.git.hramrach@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Cc: Heiner Kallweit , David Woodhouse , Brian Norris , Mark Brown , Boris Brezillon , Javier Martinez Canillas , Rafal Milecki , Jagan Teki , "Andrew F. Davis" , Mika Westerberg , Gabor Juhos , Bean Huo , Furquan Shaikh , , , To: Michal Suchanek Return-path: Content-Disposition: inline In-Reply-To: <2236d87ad516f118f58eb5df232d441f970c4499.1449052427.git.hramrach-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> Sender: linux-spi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: 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 > > --- > > - 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 -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html