From 436fb2b84dc24853298f1768c596f7ee02d582d7 Mon Sep 17 00:00:00 2001
From: Masahiro Yamada <yamada.masahiro@socionext.com>
Date: Wed, 22 Nov 2017 02:38:27 +0900
Subject: [PATCH] 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>
[Linux commit: 477544c62a84d3bacd9f90ba75ffc16c04d78071]
---
drivers/mtd/nand/nand_base.c | 8 ++++++++
include/linux/mtd/nand.h | 2 ++
2 files changed, 10 insertions(+)
diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index 16d4554fae..f3c515b6df 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -1720,6 +1720,9 @@ 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 = !IS_ALIGNED((unsigned long)buf,
+ chip->buf_align);
else
use_bufpoi = 0;
@@ -2575,6 +2578,9 @@ 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 = !IS_ALIGNED((unsigned long)buf,
+ chip->buf_align);
else
use_bufpoi = 0;
@@ -3119,6 +3125,8 @@ static void nand_set_defaults(struct nand_chip *chip, int busw)
init_waitqueue_head(&chip->controller->wq);
}
+ if (!chip->buf_align)
+ chip->buf_align = 1;
}
/* Sanitize ONFI strings so we can safely print them */
diff --git a/include/linux/mtd/nand.h b/include/linux/mtd/nand.h
index be30059632..90c6010105 100644
--- a/include/linux/mtd/nand.h
+++ b/include/linux/mtd/nand.h
@@ -752,6 +752,7 @@ nand_get_sdr_timings(const struct nand_data_interface *conf)
* setting the read-retry mode. Mostly needed for MLC NAND.
* @ecc: [BOARDSPECIFIC] ECC control structure
* @buffers: buffer structure for read/write
+ * @buf_align: minimum buffer alignment required by a platform
* @hwcontrol: platform-specific hardware control structure
* @erase: [REPLACEABLE] erase function
* @scan_bbt: [REPLACEABLE] function to scan bad block table
@@ -893,6 +894,7 @@ struct nand_chip {
struct nand_ecc_ctrl ecc;
struct nand_buffers *buffers;
+ unsigned long buf_align;
struct nand_hw_control hwcontrol;
uint8_t *bbt;
--
2.39.5