linux-kernel - [PATCH 1/1] spi-mxs: Fix chipselect glitch

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Message-ID: <20240201131540.3dlqoxlrrbzshz7w@runtux.com>
Date: Thu, 1 Feb 2024 14:15:40 +0100
From: Ralf Schlatterbeck <rsc@...tux.com>
To: Mark Brown <broonie@...nel.org>, Shawn Guo <shawnguo@...nel.org>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Pengutronix Kernel Team <kernel@...gutronix.de>,
	Fabio Estevam <festevam@...il.com>,
	NXP Linux Team <linux-imx@....com>, Vinod Koul <vkoul@...nel.org>,
	Miquel Raynal <miquel.raynal@...tlin.com>,
	linux-spi@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 1/1] spi-mxs: Fix chipselect glitch

There was a change in the mxs-dma engine that uses a new custom flag.
The change was not applied to the mxs spi driver.
This results in chipselect being deasserted too early.
This fixes the chipselect problem by using the new flag in the mxs-spi
driver.

Fixes: ceeeb99cd821 ("dmaengine: mxs: rename custom flag")
Signed-off-by: Ralf Schlatterbeck <rsc@...tux.com>
---
For oscilloscope screenshots and a verbose explanation see my blog post
at https://blog.runtux.com/posts/2024/02/01/

 drivers/spi/spi-mxs.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/spi/spi-mxs.c b/drivers/spi/spi-mxs.c
index 1bf080339b5a..a296050c8bd3 100644
--- a/drivers/spi/spi-mxs.c
+++ b/drivers/spi/spi-mxs.c
@@ -39,6 +39,7 @@
 #include <linux/spi/spi.h>
 #include <linux/spi/mxs-spi.h>
 #include <trace/events/spi.h>
+#include <linux/dma/mxs-dma.h>
 
 #define DRIVER_NAME		"mxs-spi"
 
@@ -251,8 +252,9 @@ static int mxs_spi_txrx_dma(struct mxs_spi *spi,
 
 		desc = dmaengine_prep_slave_sg(ssp->dmach,
 				&dma_xfer[sg_count].sg, 1,
-				(flags & TXRX_WRITE) ? DMA_MEM_TO_DEV : DMA_DEV_TO_MEM,
-				DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+				(flags & TXRX_WRITE)
+				? DMA_MEM_TO_DEV : DMA_DEV_TO_MEM,
+				DMA_PREP_INTERRUPT | MXS_DMA_CTRL_WAIT4END);
 
 		if (!desc) {
 			dev_err(ssp->dev,
-- 
2.20.1

-- 
Dr. Ralf Schlatterbeck                  Tel:   +43/2243/26465-16
Open Source Consulting                  www:   www.runtux.com
Reichergasse 131, A-3411 Weidling       email: office@...tux.com