From: Yogesh Gaur <yogeshnarayan.gaur@nxp.com>
Date: Wed, 13 Jun 2018 11:39:18 +0530
Subject: mtd: devices: m25p80: Make sure WRITE_EN is issued before each write

Git-commit: 3baa8ec88c2feb902328e59a4dcf0f0aaab7d2ff
Patch-mainline: v4.20-rc1
References: fate#326572

Some SPI controllers can't write nor->page_size bytes in a single step
because their TX FIFO is too small, but when that happens we should
make sure a WRITE_EN command before each write access and READ_SR command
after each write access is issued.

The core is already taking care of that, so all we have to do here is
return the actual number of bytes that were written during the
spi_mem_exec_op() operation.

Signed-off-by: Yogesh Gaur <yogeshnarayan.gaur@nxp.com>
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
Signed-off-by: Mian Yousaf Kaukab <yousaf.kaukab@suse.com>
---
 drivers/mtd/devices/m25p80.c | 23 ++++++++---------------
 1 file changed, 8 insertions(+), 15 deletions(-)

diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c
index cbfafc453274..cb14cf985b95 100644
--- a/drivers/mtd/devices/m25p80.c
+++ b/drivers/mtd/devices/m25p80.c
@@ -70,7 +70,6 @@ static ssize_t m25p80_write(struct spi_nor *nor, loff_t to, size_t len,
 				   SPI_MEM_OP_ADDR(nor->addr_width, to, 1),
 				   SPI_MEM_OP_NO_DUMMY,
 				   SPI_MEM_OP_DATA_OUT(len, buf, 1));
-	size_t remaining = len;
 	int ret;
 
 	/* get transfer protocols. */
@@ -81,22 +80,16 @@ static ssize_t m25p80_write(struct spi_nor *nor, loff_t to, size_t len,
 	if (nor->program_opcode == SPINOR_OP_AAI_WP && nor->sst_write_second)
 		op.addr.nbytes = 0;
 
-	while (remaining) {
-		op.data.nbytes = remaining < UINT_MAX ? remaining : UINT_MAX;
-		ret = spi_mem_adjust_op_size(flash->spimem, &op);
-		if (ret)
-			return ret;
-
-		ret = spi_mem_exec_op(flash->spimem, &op);
-		if (ret)
-			return ret;
+	ret = spi_mem_adjust_op_size(flash->spimem, &op);
+	if (ret)
+		return ret;
+	op.data.nbytes = len < op.data.nbytes ? len : op.data.nbytes;
 
-		op.addr.val += op.data.nbytes;
-		remaining -= op.data.nbytes;
-		op.data.buf.out += op.data.nbytes;
-	}
+	ret = spi_mem_exec_op(flash->spimem, &op);
+	if (ret)
+		return ret;
 
-	return len;
+	return op.data.nbytes;
 }
 
 /*
-- 
2.11.0