openwrt/target/linux/ipq40xx/patches-4.14/050-0005-mtd-nand-force-drivers-to-explicitly-send-READ-PROG-.patch

From 25f815f66a141436df8a4c45e5d2765272aea2ac Mon Sep 17 00:00:00 2001
From: Boris Brezillon <boris.brezillon@free-electrons.com>
Date: Thu, 30 Nov 2017 18:01:30 +0100
Subject: [PATCH 5/7] mtd: nand: force drivers to explicitly send READ/PROG
 commands

The core currently send the READ0 and SEQIN+PAGEPROG commands in
nand_do_read/write_ops(). This is inconsistent with
->read/write_oob[_raw]() hooks behavior which are expected to send
these commands.

There's already a flag (NAND_ECC_CUSTOM_PAGE_ACCESS) to inform the core
that a specific controller wants to send the READ/SEQIN+PAGEPROG
commands on its own, but it's an opt-in flag, and existing drivers are
unlikely to be updated to pass it.

Moreover, some controllers cannot dissociate the READ/PAGEPROG commands
from the associated data transfer and ECC engine activation, and
developers have to hack things in their ->cmdfunc() implementation to
handle such complex cases, or have to accept the perf penalty of sending
twice the same command.
To address this problem we are planning on adding a new interface which
is passed all information about a NAND operation (including the amount
of data to transfer) and replacing all calls to ->cmdfunc() to calls to
this new ->exec_op() hook. But, in order to do that, we need to have all
->cmdfunc() calls placed near their associated ->read/write_buf/byte()
calls.

Modify the core and relevant drivers to make NAND_ECC_CUSTOM_PAGE_ACCESS
the default case, and remove this flag.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
[miquel.raynal@free-electrons.com: tested, fixed and rebased on nand/next]
Signed-off-by: Miquel Raynal <miquel.raynal@free-electrons.com>
Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>
---
 drivers/mtd/nand/qcom_nandc.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

--- a/drivers/mtd/nand/qcom_nandc.c
+++ b/drivers/mtd/nand/qcom_nandc.c
@@ -1725,6 +1725,7 @@ static int qcom_nandc_read_page(struct m
 	u8 *data_buf, *oob_buf = NULL;
 	int ret;
 
+	nand_read_page_op(chip, page, 0, NULL, 0);
 	data_buf = buf;
 	oob_buf = oob_required ? chip->oob_poi : NULL;
 
@@ -1750,6 +1751,7 @@ static int qcom_nandc_read_page_raw(stru
 	int i, ret;
 	int read_loc;
 
+	nand_read_page_op(chip, page, 0, NULL, 0);
 	data_buf = buf;
 	oob_buf = chip->oob_poi;
 
@@ -1850,6 +1852,8 @@ static int qcom_nandc_write_page(struct
 	u8 *data_buf, *oob_buf;
 	int i, ret;
 
+	nand_prog_page_begin_op(chip, page, 0, NULL, 0);
+
 	clear_read_regs(nandc);
 	clear_bam_transaction(nandc);
 
@@ -1902,6 +1906,9 @@ static int qcom_nandc_write_page(struct
 
 	free_descs(nandc);
 
+	if (!ret)
+		ret = nand_prog_page_end_op(chip);
+
 	return ret;
 }
 
@@ -1916,6 +1923,7 @@ static int qcom_nandc_write_page_raw(str
 	u8 *data_buf, *oob_buf;
 	int i, ret;
 
+	nand_prog_page_begin_op(chip, page, 0, NULL, 0);
 	clear_read_regs(nandc);
 	clear_bam_transaction(nandc);
 
@@ -1970,6 +1978,9 @@ static int qcom_nandc_write_page_raw(str
 
 	free_descs(nandc);
 
+	if (!ret)
+		ret = nand_prog_page_end_op(chip);
+
 	return ret;
 }