[PATCH v2] spi: rzv2h-rspi: Fix SPDR read access width for 16-bit RX

[Felix Gu]

The RZ/V2H hardware manual (section 7.5.2.2.1) specifies that read access
size for the SPI Data Register (SPDR) are fixed at 32 bits. The
RZV2H_RSPI_RX macro for the 16-bit data path used readw(), violating
this requirement.

Switch to readl() for the 16-bit RX path to conform to the hardware
specification.

Fixes: 8b61c8919dff ("spi: Add driver for the RZ/V2H(P) RSPI IP")
Suggested-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Signed-off-by: Felix Gu <ustc.gu@xxxxxxxxx>
---
Changes in v2:
- Fix comments from Geert.
- Link to v1: https://patch.msgid.link/20260605-rzv2h-rspi-v1-1-c1d5ed562249@xxxxxxxxx

To: Fabrizio Castro <fabrizio.castro.jz@xxxxxxxxxxx>
To: Mark Brown <broonie@xxxxxxxxxx>
Cc: linux-spi@xxxxxxxxxxxxxxx
Cc: linux-renesas-soc@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
 drivers/spi/spi-rzv2h-rspi.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi-rzv2h-rspi.c b/drivers/spi/spi-rzv2h-rspi.c
index 1655efda7d20..6ed3fad873b8 100644
--- a/drivers/spi/spi-rzv2h-rspi.c
+++ b/drivers/spi/spi-rzv2h-rspi.c
@@ -135,8 +135,9 @@ static inline void rzv2h_rspi_rx_##type(struct rzv2h_rspi_priv *rspi,	\
 RZV2H_RSPI_TX(writel, u32)
 RZV2H_RSPI_TX(writew, u16)
 RZV2H_RSPI_TX(writeb, u8)
+/* The read access size for RSPI_SPDR is fixed at 32 bits */
 RZV2H_RSPI_RX(readl, u32)
-RZV2H_RSPI_RX(readw, u16)
+RZV2H_RSPI_RX(readl, u16)
 RZV2H_RSPI_RX(readl, u8)
 
 static void rzv2h_rspi_reg_rmw(const struct rzv2h_rspi_priv *rspi,

---
base-commit: a225caacc36546a09586e3ece36c0313146e7da9
change-id: 20260605-rzv2h-rspi-3c8dd168fb72

Best regards,
--  
Felix Gu <ustc.gu@xxxxxxxxx>