From: Boris Brezillon <redacted>

commit 0ebb261a0b2d090de618a383d2378d4a00834958 upstream.

When defining spi_mem_op templates we don't necessarily know the size
that will be passed when the template is actually used, and basing the
supports_op() check on op->data.nbytes to know whether there will be
data transferred for a specific operation is this not possible.

Add SPI_MEM_NO_DATA to the spi_mem_data_dir enum so that we can base
our checks on op->data.dir instead of op->data.nbytes.

Signed-off-by: Boris Brezillon <redacted>
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
[PL: manually applied the changes]
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
---
 drivers/spi/spi-mem.c       | 2 +-
 include/linux/spi/spi-mem.h | 2 ++
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi-mem.c b/drivers/spi/spi-mem.c
index 62a7b80801d2..967f581bca4f 100644
--- a/drivers/spi/spi-mem.c
+++ b/drivers/spi/spi-mem.c

@@ -142,7 +142,7 @@ static bool spi_mem_default_supports_op(struct spi_mem *mem,
 	    spi_check_buswidth_req(mem, op->dummy.buswidth, true))
 		return false;
 
-	if (op->data.nbytes &&
+	if (op->data.dir != SPI_MEM_NO_DATA &&
 	    spi_check_buswidth_req(mem, op->data.buswidth,
 				   op->data.dir == SPI_MEM_DATA_OUT))
 		return false;

diff --git a/include/linux/spi/spi-mem.h b/include/linux/spi/spi-mem.h
index 69ee30456864..80db2de83402 100644
--- a/include/linux/spi/spi-mem.h
+++ b/include/linux/spi/spi-mem.h

@@ -57,10 +57,12 @@
 /**
  * enum spi_mem_data_dir - describes the direction of a SPI memory data
  *			   transfer from the controller perspective
+ * @SPI_MEM_NO_DATA: no data transferred
  * @SPI_MEM_DATA_IN: data coming from the SPI memory
  * @SPI_MEM_DATA_OUT: data sent the SPI memory
  */
 enum spi_mem_data_dir {
+	SPI_MEM_NO_DATA,
 	SPI_MEM_DATA_IN,
 	SPI_MEM_DATA_OUT,
 };

-- 
2.17.1