linux-kernel - [PATCH v2 08/14] spi: spi-fsl-dspi: Avoid setup

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Message-Id: <20250522-james-nxp-spi-v2-8-bea884630cfb@linaro.org>
Date: Thu, 22 May 2025 15:51:37 +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>, 
 Matti Vaittinen <mazziesaccount@...il.com>
Cc: 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>, Chao Fu <B44548@...escale.com>, 
 Xiubo Li <Li.Xiubo@...escale.com>, Lukasz Majewski <lukma@...x.de>, 
 linux-spi@...r.kernel.org, imx@...ts.linux.dev, 
 linux-kernel@...r.kernel.org, devicetree@...r.kernel.org, 
 linux-arm-kernel@...ts.infradead.org, 
 Vladimir Oltean <vladimir.oltean@....com>, 
 Dan Carpenter <dan.carpenter@...aro.org>, 
 Larisa Grigore <larisa.grigore@....com>, 
 James Clark <james.clark@...aro.org>
Subject: [PATCH v2 08/14] spi: spi-fsl-dspi: Avoid setup_accel logic for
 DMA transfers

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

Repacking multiple smaller words into larger ones to make use of the
full FIFO doesn't save anything in DMA mode, so don't bother doing it.

Signed-off-by: Larisa Grigore <larisa.grigore@....com>
Signed-off-by: James Clark <james.clark@...aro.org>
---
 drivers/spi/spi-fsl-dspi.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/spi/spi-fsl-dspi.c b/drivers/spi/spi-fsl-dspi.c
index 814a92b8064e..24a51267cb4d 100644
--- a/drivers/spi/spi-fsl-dspi.c
+++ b/drivers/spi/spi-fsl-dspi.c
@@ -850,8 +850,12 @@ 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) {
@@ -860,10 +864,7 @@ 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