linux-kernel - [PATCH] spi: imx: fix the burst length at DMA mode and CPU mode

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Message-Id: <20240131024623.329240-1-carlos.song@nxp.com>
Date: Wed, 31 Jan 2024 10:46:23 +0800
From: carlos.song@....com
To: broonie@...nel.org,
	shawnguo@...nel.org,
	s.hauer@...gutronix.de,
	kernel@...gutronix.de,
	linux-imx@....com,
	benjamin@...ler.one,
	stefanmoring@...il.com
Cc: linux-spi@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] spi: imx: fix the burst length at DMA mode and CPU mode

From: Carlos Song <carlos.song@....com>

For DMA mode, the bus width of the DMA is equal to the size of data
word, so burst length should be configured as bits per word.

For CPU mode, because of the spi transfer len is in byte, so burst
length should be configured as bits per byte * spi_imx->count.

Signed-off-by: Carlos Song <carlos.song@....com>
Reviewed-by: Clark Wang <xiaoning.wang@....com>
Fixes: e9b220aeacf1 ("spi: spi-imx: correctly configure burst length when using dma")
Fixes: 5f66db08cbd3 ("spi: imx: Take in account bits per word instead of assuming 8-bits")
---
 drivers/spi/spi-imx.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c
index 546cdce525fc..b4ade2d53fef 100644
--- a/drivers/spi/spi-imx.c
+++ b/drivers/spi/spi-imx.c
@@ -54,7 +54,7 @@ MODULE_PARM_DESC(polling_limit_us,
 #define MX51_ECSPI_CTRL_MAX_BURST	512
 /* The maximum bytes that IMX53_ECSPI can transfer in target mode.*/
 #define MX53_MAX_TRANSFER_BYTES		512
-
+#define BITS_PER_BYTE	8
 enum spi_imx_devtype {
 	IMX1_CSPI,
 	IMX21_CSPI,
@@ -660,15 +660,14 @@ static int mx51_ecspi_prepare_transfer(struct spi_imx_data *spi_imx,
 			<< MX51_ECSPI_CTRL_BL_OFFSET;
 	else {
 		if (spi_imx->usedma) {
-			ctrl |= (spi_imx->bits_per_word *
-				spi_imx_bytes_per_word(spi_imx->bits_per_word) - 1)
+			ctrl |= (spi_imx->bits_per_word - 1)
 				<< MX51_ECSPI_CTRL_BL_OFFSET;
 		} else {
 			if (spi_imx->count >= MX51_ECSPI_CTRL_MAX_BURST)
-				ctrl |= (MX51_ECSPI_CTRL_MAX_BURST - 1)
+				ctrl |= (MX51_ECSPI_CTRL_MAX_BURST * BITS_PER_BYTE - 1)
 						<< MX51_ECSPI_CTRL_BL_OFFSET;
 			else
-				ctrl |= (spi_imx->count * spi_imx->bits_per_word - 1)
+				ctrl |= (spi_imx->count * BITS_PER_BYTE - 1)
 						<< MX51_ECSPI_CTRL_BL_OFFSET;
 		}
 	}
-- 
2.34.1