[PATCH 6.7 675/713] spi: spi-imx: fix off-by-one in mx51 CPU mode burst length

Sasha Levin
2024-03-24T22:58:33Z

From: Adam Butcher <adam@jessamine.co.uk>

[ Upstream commit cf6d79a0f5769b5f4d9579ddaf88d2c30b03b873 ]

c712c05e46c8 ("spi: imx: fix the burst length at DMA mode and CPU mode")
corrects three cases of setting the ECSPI burst length but erroneously
leaves the in-range CPU case one bit to big (in that field a value of
0 means 1 bit). The effect was that transmissions that should have been
8-bit bytes appeared as 9-bit causing failed communication with SPI
devices.

Link: https://lore.kernel.org/all/20240201105451.507005-1-carlos.song@nxp.com/
Link: https://lore.kernel.org/all/20240204091912.36488-1-carlos.song@nxp.com/
Fixes: c712c05e46c8 ("spi: imx: fix the burst length at DMA mode and CPU mode")
Signed-off-by: Adam Butcher <adam@jessamine.co.uk>
Link: https://msgid.link/r/20240318175119.3334-1-adam@jessamine.co.uk
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/spi/spi-imx.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c
index e2d3e3ec13789..0e479c5406217 100644
--- a/drivers/spi/spi-imx.c
+++ b/drivers/spi/spi-imx.c
@@ -668,8 +668,8 @@ static int mx51_ecspi_prepare_transfer(struct spi_imx_data *spi_imx,
ctrl |= (MX51_ECSPI_CTRL_MAX_BURST * BITS_PER_BYTE - 1)
<< MX51_ECSPI_CTRL_BL_OFFSET;
else
- ctrl |= spi_imx->count / DIV_ROUND_UP(spi_imx->bits_per_word,
- BITS_PER_BYTE) * spi_imx->bits_per_word
+ ctrl |= (spi_imx->count / DIV_ROUND_UP(spi_imx->bits_per_word,
+ BITS_PER_BYTE) * spi_imx->bits_per_word - 1)
<< MX51_ECSPI_CTRL_BL_OFFSET;
}
}
--
2.43.0