mtd: nand: allow drivers to request minimum alignment for passed buffer
In some cases, nand_do_{read,write}_ops is passed with unaligned
ops->datbuf. Drivers using DMA will be unhappy about unaligned
buffer.
The new struct member, buf_align, represents the minimum alignment
the driver require for the buffer. If the buffer passed from the
upper MTD layer does not have enough alignment, nand_do_*_ops will
use bufpoi.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index c796d0e..ed49a1d 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -1954,7 +1954,9 @@ static int nand_do_read_ops(struct mtd_info *mtd, loff_t from,
if (!aligned)
use_bufpoi = 1;
else if (chip->options & NAND_USE_BOUNCE_BUFFER)
- use_bufpoi = !virt_addr_valid(buf);
+ use_bufpoi = !virt_addr_valid(buf) ||
+ !IS_ALIGNED((unsigned long)buf,
+ chip->buf_align);
else
use_bufpoi = 0;
@@ -2810,7 +2812,9 @@ static int nand_do_write_ops(struct mtd_info *mtd, loff_t to,
if (part_pagewr)
use_bufpoi = 1;
else if (chip->options & NAND_USE_BOUNCE_BUFFER)
- use_bufpoi = !virt_addr_valid(buf);
+ use_bufpoi = !virt_addr_valid(buf) ||
+ !IS_ALIGNED((unsigned long)buf,
+ chip->buf_align);
else
use_bufpoi = 0;
@@ -3429,6 +3433,8 @@ static void nand_set_defaults(struct nand_chip *chip)
nand_hw_control_init(chip->controller);
}
+ if (!chip->buf_align)
+ chip->buf_align = 1;
}
/* Sanitize ONFI strings so we can safely print them */