linux-kernel - [PATCH] spi: tegra114: Preserve SPI mode bits in def_command1

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Message-ID: <20260204141212.1540382-1-va@nvidia.com>
Date: Wed, 4 Feb 2026 14:12:12 +0000
From: Vishwaroop A <va@...dia.com>
To: Mark Brown <broonie@...nel.org>
CC: Laxman Dewangan <ldewangan@...dia.com>, Thierry Reding
	<thierry.reding@...il.com>, Jonathan Hunter <jonathanh@...dia.com>,
	Vishwaroop A <va@...dia.com>, <linux-spi@...r.kernel.org>,
	<linux-tegra@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH] spi: tegra114: Preserve SPI mode bits in def_command1_reg

The COMMAND1 register bits [29:28] set the SPI mode, which controls
the clock idle level. When a transfer ends, tegra_spi_transfer_end()
writes def_command1_reg back to restore the default state, but this
register value currently lacks the mode bits. This results in the
clock always being configured as idle low, breaking devices that
need it high.

Fix this by storing the mode bits in def_command1_reg during setup,
to prevent this field from always being cleared.

Fixes: f333a331adfa ("spi/tegra114: add spi driver")
Signed-off-by: Vishwaroop A <va@...dia.com>
---
 drivers/spi/spi-tegra114.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/spi/spi-tegra114.c b/drivers/spi/spi-tegra114.c
index 795a8482c2c7..48fb11fea55f 100644
--- a/drivers/spi/spi-tegra114.c
+++ b/drivers/spi/spi-tegra114.c
@@ -978,11 +978,14 @@ static int tegra_spi_setup(struct spi_device *spi)
 	if (spi_get_csgpiod(spi, 0))
 		gpiod_set_value(spi_get_csgpiod(spi, 0), 0);
 
+	/* Update default register to include CS polarity and SPI mode */
 	val = tspi->def_command1_reg;
 	if (spi->mode & SPI_CS_HIGH)
 		val &= ~SPI_CS_POL_INACTIVE(spi_get_chipselect(spi, 0));
 	else
 		val |= SPI_CS_POL_INACTIVE(spi_get_chipselect(spi, 0));
+	val &= ~SPI_CONTROL_MODE_MASK;
+	val |= SPI_MODE_SEL(spi->mode & 0x3);
 	tspi->def_command1_reg = val;
 	tegra_spi_writel(tspi, tspi->def_command1_reg, SPI_COMMAND1);
 	spin_unlock_irqrestore(&tspi->lock, flags);
-- 
2.17.1