linux-kernel - [PATCH v2 1/6] mtd: spi-nor: core: use 2 data bytes for template ops

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Date:   Mon, 31 May 2021 23:47:52 +0530
From:   Pratyush Yadav <p.yadav@...com>
To:     Tudor Ambarus <tudor.ambarus@...rochip.com>,
        Michael Walle <michael@...le.cc>,
        Pratyush Yadav <p.yadav@...com>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        Mark Brown <broonie@...nel.org>,
        <linux-mtd@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
        <linux-spi@...r.kernel.org>
Subject: [PATCH v2 1/6] mtd: spi-nor: core: use 2 data bytes for template ops

The template ops used in spi_nor_spimem_check_pp() and
spi_nor_spimem_check_readop() currently set the data phase to 1 byte
long. This is problematic for 8D-8D-8D protocol where odd length data
phase is invalid since one cycle transfers 2 bytes and odd number of
bytes would mean half a cycle is left over. This could result in a
controller rejecting the op as "not supported" even though it actually
supports the protocol.

Change the data length to 2 bytes in these templates. One might argue
that this should only be done for 8D-8D-8D operations but when talking
about these templates, there is no functional difference between one and
two bytes, even in STR modes.

Signed-off-by: Pratyush Yadav <p.yadav@...com>
---

(no changes since v1)

 drivers/mtd/spi-nor/core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
index f6a6ef2d8bd8..d521ca577884 100644
--- a/drivers/mtd/spi-nor/core.c
+++ b/drivers/mtd/spi-nor/core.c
@@ -2143,7 +2143,7 @@ static int spi_nor_spimem_check_readop(struct spi_nor *nor,
 	struct spi_mem_op op = SPI_MEM_OP(SPI_MEM_OP_CMD(read->opcode, 0),
 					  SPI_MEM_OP_ADDR(3, 0, 0),
 					  SPI_MEM_OP_DUMMY(1, 0),
-					  SPI_MEM_OP_DATA_IN(1, NULL, 0));
+					  SPI_MEM_OP_DATA_IN(2, NULL, 0));
 
 	spi_nor_spimem_setup_op(nor, &op, read->proto);
 
@@ -2169,7 +2169,7 @@ static int spi_nor_spimem_check_pp(struct spi_nor *nor,
 	struct spi_mem_op op = SPI_MEM_OP(SPI_MEM_OP_CMD(pp->opcode, 0),
 					  SPI_MEM_OP_ADDR(3, 0, 0),
 					  SPI_MEM_OP_NO_DUMMY,
-					  SPI_MEM_OP_DATA_OUT(1, NULL, 0));
+					  SPI_MEM_OP_DATA_OUT(2, NULL, 0));
 
 	spi_nor_spimem_setup_op(nor, &op, pp->proto);
 
-- 
2.30.0