diff mbox series

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

Message ID 20210531181757.19458-2-p.yadav@ti.com (mailing list archive)
State New
Headers show
Series Avoid odd length/address read/writes in 8D-8D-8D mode. | expand

Commit Message

Pratyush Yadav May 31, 2021, 6:17 p.m. UTC
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@ti.com>
---

(no changes since v1)

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

Comments

Michael Walle June 1, 2021, 12:36 p.m. UTC | #1
Am 2021-05-31 20:17, schrieb Pratyush Yadav:
> 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@ti.com>
> ---

Reviewed-by: Michael Walle <michael@walle.cc>
diff mbox series

Patch

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);