[PATCH 6.18 150/752] spi: spi-mem: Limit octal DTR constraints to octal DTR situations

Sasha Levin
2026-02-28T17:50:15Z

From: Miquel Raynal <miquel.raynal@bootlin.com>

[ Upstream commit 8618271887ca10ac5108fe7e1d82ba8f1b152cf9 ]

In this helper, any operation with a single DTR cycle (like 1S-1S-8D) is
considered requiring a duplicated command opcode. This is wrong as this
constraint only applies to octal DTR operations (8D-8D-8D).

Narrow the application of this constraint to the concerned bus
interface.

Note: none of the possible XD-XD-XD pattern, with X being one of {1, 2,
4} would benefit from this check either as there is only in octal DTR
mode that a single clock edge would be enough to transmit the full
opcode.

Make sure the constraint of expecting two bytes for the command is
applied to the relevant bus interface.

Reviewed-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://patch.msgid.link/20260109-winbond-v6-17-rc1-oddr-v2-3-1fff6a2ddb80@bootlin.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/spi/spi-mem.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/spi/spi-mem.c b/drivers/spi/spi-mem.c
index 064b99204d9ac..71e3eaf59df97 100644
--- a/drivers/spi/spi-mem.c
+++ b/drivers/spi/spi-mem.c
@@ -175,8 +175,19 @@ bool spi_mem_default_supports_op(struct spi_mem *mem,
if (op->data.swap16 && !spi_mem_controller_is_capable(ctlr, swap16))
return false;

- if (op->cmd.nbytes != 2)
- return false;
+ /* Extra 8D-8D-8D limitations */
+ if (op->cmd.dtr && op->cmd.buswidth == 8) {
+ if (op->cmd.nbytes != 2)
+ return false;
+
+ if ((op->addr.nbytes % 2) ||
+ (op->dummy.nbytes % 2) ||
+ (op->data.nbytes % 2)) {
+ dev_err(&ctlr->dev,
+ "Even byte numbers not allowed in octal DTR operations\n");
+ return false;
+ }
+ }
} else {
if (op->cmd.nbytes != 1)
return false;
--
2.51.0