linux-kernel - [PATCH v2 4/9] spi: spi-fsl-lpspi: Clear status register after disabling the module

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Message-Id: <20250828-james-nxp-lpspi-v2-4-6262b9aa9be4@linaro.org>
Date: Thu, 28 Aug 2025 11:14:43 +0100
From: James Clark <james.clark@...aro.org>
To: Frank Li <Frank.Li@....com>, Mark Brown <broonie@...nel.org>, 
 Clark Wang <xiaoning.wang@....com>, Rob Herring <robh@...nel.org>, 
 Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, Shawn Guo <shawnguo@...nel.org>, 
 Sascha Hauer <s.hauer@...gutronix.de>, Fabio Estevam <festevam@...il.com>, 
 Larisa Grigore <larisa.grigore@....nxp.com>, 
 Larisa Grigore <larisa.grigore@....com>, 
 Ghennadi Procopciuc <ghennadi.procopciuc@....com>, 
 Ciprianmarian Costea <ciprianmarian.costea@....com>, s32@....com
Cc: James Clark <james.clark@...aro.org>, linux-spi@...r.kernel.org, 
 imx@...ts.linux.dev, linux-kernel@...r.kernel.org, 
 devicetree@...r.kernel.org
Subject: [PATCH v2 4/9] spi: spi-fsl-lpspi: Clear status register after
 disabling the module

From: Larisa Grigore <larisa.grigore@....com>

Clear the error flags after disabling the module to avoid the case when
a flag is set again between flag clear and module disable. And use
SR_CLEAR_MASK to replace hardcoded value for improved readability.

Although fsl_lpspi_reset() was only introduced in commit a15dc3d657fa
("spi: lpspi: Fix CLK pin becomes low before one transfer"), the
original driver only reset SR in the interrupt handler, making it
vulnerable to the same issue. Therefore the fixes commit is set at the
introduction of the driver.

Fixes: 5314987de5e5 ("spi: imx: add lpspi bus driver")
Signed-off-by: Larisa Grigore <larisa.grigore@....com>
Signed-off-by: Ciprian Marian Costea <ciprianmarian.costea@....com>
Reviewed-by: Frank Li <Frank.Li@....com>
Signed-off-by: James Clark <james.clark@...aro.org>
---
 drivers/spi/spi-fsl-lpspi.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/spi/spi-fsl-lpspi.c b/drivers/spi/spi-fsl-lpspi.c
index e50261e9a1fa..fc4d49f0717e 100644
--- a/drivers/spi/spi-fsl-lpspi.c
+++ b/drivers/spi/spi-fsl-lpspi.c
@@ -83,6 +83,8 @@
 #define TCR_RXMSK	BIT(19)
 #define TCR_TXMSK	BIT(18)
 
+#define SR_CLEAR_MASK	GENMASK(13, 8)
+
 struct fsl_lpspi_devtype_data {
 	u8 prescale_max;
 };
@@ -535,14 +537,13 @@ static int fsl_lpspi_reset(struct fsl_lpspi_data *fsl_lpspi)
 		fsl_lpspi_intctrl(fsl_lpspi, 0);
 	}
 
-	/* W1C for all flags in SR */
-	temp = 0x3F << 8;
-	writel(temp, fsl_lpspi->base + IMX7ULP_SR);
-
 	/* Clear FIFO and disable module */
 	temp = CR_RRF | CR_RTF;
 	writel(temp, fsl_lpspi->base + IMX7ULP_CR);
 
+	/* W1C for all flags in SR */
+	writel(SR_CLEAR_MASK, fsl_lpspi->base + IMX7ULP_SR);
+
 	return 0;
 }
 

-- 
2.34.1