linux-kernel - [PATCH 1/3] spi: spi-nxp-fspi: re-config the clock rate when operation require new clock rate

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Message-Id: <20250922-fspi-fix-v1-1-ff4315359d31@nxp.com>
Date: Mon, 22 Sep 2025 16:47:13 +0800
From: Haibo Chen <haibo.chen@....com>
To: Han Xu <han.xu@....com>, Yogesh Gaur <yogeshgaur.83@...il.com>, 
 Mark Brown <broonie@...nel.org>, Miquel Raynal <miquel.raynal@...tlin.com>, 
 Frank Li <Frank.Li@....com>
Cc: linux-spi@...r.kernel.org, imx@...ts.linux.dev, 
 linux-kernel@...r.kernel.org, Haibo Chen <haibo.chen@....com>
Subject: [PATCH 1/3] spi: spi-nxp-fspi: re-config the clock rate when
 operation require new clock rate

Current operation contain the max_freq, so new coming operation may use
new clock rate, need to re-config the clock rate to match the requirement.

Fixes: 26851cf65ffc ("spi: nxp-fspi: Support per spi-mem operation frequency switches")
Signed-off-by: Haibo Chen <haibo.chen@....com>
---
 drivers/spi/spi-nxp-fspi.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/spi/spi-nxp-fspi.c b/drivers/spi/spi-nxp-fspi.c
index f9371f98a65bdc7e5eaa612c0770a6228bdda364..4e82f9e900acb91c6de46559efd265f07cf4437d 100644
--- a/drivers/spi/spi-nxp-fspi.c
+++ b/drivers/spi/spi-nxp-fspi.c
@@ -404,6 +404,8 @@ struct nxp_fspi {
 #define FSPI_NEED_INIT		BIT(0)
 #define FSPI_DTR_MODE		BIT(1)
 	int flags;
+	/* save the previous operation clock rate */
+	unsigned long pre_op_rate;
 };
 
 static inline int needs_ip_only(struct nxp_fspi *f)
@@ -780,11 +782,17 @@ static void nxp_fspi_select_mem(struct nxp_fspi *f, struct spi_device *spi,
 	uint64_t size_kb;
 
 	/*
-	 * Return, if previously selected target device is same as current
-	 * requested target device. Also the DTR or STR mode do not change.
+	 * Return when following condition all meet,
+	 * 1, if previously selected target device is same as current
+	 *    requested target device.
+	 * 2, the DTR or STR mode do not change.
+	 * 3, previous operation max rate equals current one.
+	 *
+	 * For other case, need to re-config.
 	 */
 	if ((f->selected == spi_get_chipselect(spi, 0)) &&
-	    (!!(f->flags & FSPI_DTR_MODE) == op_is_dtr))
+	    (!!(f->flags & FSPI_DTR_MODE) == op_is_dtr) &&
+	    (f->pre_op_rate == op->max_freq))
 		return;
 
 	/* Reset FLSHxxCR0 registers */
@@ -832,6 +840,8 @@ static void nxp_fspi_select_mem(struct nxp_fspi *f, struct spi_device *spi,
 	else
 		nxp_fspi_dll_override(f);
 
+	f->pre_op_rate = op->max_freq;
+
 	f->selected = spi_get_chipselect(spi, 0);
 }
 

-- 
2.34.1