linux-kernel - [PATCH 06/14] spi: spi-fsl-dspi: Avoid setup

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Message-Id: <20250509-james-nxp-spi-v1-6-32bfcd2fea11@linaro.org>
Date: Fri, 09 May 2025 12:05:53 +0100
From: James Clark <james.clark@...aro.org>
To: Vladimir Oltean <olteanv@...il.com>, Mark Brown <broonie@...nel.org>, 
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, Frank Li <Frank.Li@....com>, 
 Chester Lin <chester62515@...il.com>, Matthias Brugger <mbrugger@...e.com>, 
 Ghennadi Procopciuc <ghennadi.procopciuc@....nxp.com>, 
 NXP S32 Linux Team <s32@....com>, Shawn Guo <shawnguo@...nel.org>, 
 Sascha Hauer <s.hauer@...gutronix.de>, 
 Pengutronix Kernel Team <kernel@...gutronix.de>, 
 Fabio Estevam <festevam@...il.com>, larisa.grigore@....com, arnd@...aro.org, 
 andrei.stefanescu@....com, dan.carpenter@...aro.org
Cc: linux-spi@...r.kernel.org, imx@...ts.linux.dev, 
 linux-kernel@...r.kernel.org, devicetree@...r.kernel.org, 
 linux-arm-kernel@...ts.infradead.org, James Clark <james.clark@...aro.org>
Subject: [PATCH 06/14] spi: spi-fsl-dspi: Avoid setup_accel logic for DMA
 transfers

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

DMA can't repack the buffer like the CPU can, so skip the accel path
which may change the word size and break DMA assumptions.

Signed-off-by: Larisa Grigore <larisa.grigore@....com>
Signed-off-by: James Clark <james.clark@...aro.org>
---
 drivers/spi/spi-fsl-dspi.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/drivers/spi/spi-fsl-dspi.c b/drivers/spi/spi-fsl-dspi.c
index f7f9425a19e1..902bf23d276a 100644
--- a/drivers/spi/spi-fsl-dspi.c
+++ b/drivers/spi/spi-fsl-dspi.c
@@ -849,8 +849,8 @@ static void dspi_setup_accel(struct fsl_dspi *dspi)
 	struct spi_transfer *xfer = dspi->cur_transfer;
 	bool odd = !!(dspi->len & 1);
 
-	/* No accel for frames not multiple of 8 bits at the moment */
-	if (xfer->bits_per_word % 8)
+	/* No accel for DMA transfers or frames not multiples of 8 bits at the moment */
+	if (dspi->devtype_data->trans_mode == DSPI_DMA_MODE || xfer->bits_per_word % 8)
 		goto no_accel;
 
 	if (!odd && dspi->len <= dspi->devtype_data->fifo_size * 2) {
@@ -859,10 +859,7 @@ static void dspi_setup_accel(struct fsl_dspi *dspi)
 		dspi->oper_bits_per_word = 8;
 	} else {
 		/* Start off with maximum supported by hardware */
-		if (dspi->devtype_data->trans_mode == DSPI_XSPI_MODE)
-			dspi->oper_bits_per_word = 32;
-		else
-			dspi->oper_bits_per_word = 16;
+		dspi->oper_bits_per_word = 32;
 
 		/*
 		 * And go down only if the buffer can't be sent with

-- 
2.34.1