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From:   Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
To:     Shawn Guo <shawnguo@kernel.org>,
        Sascha Hauer <s.hauer@pengutronix.de>
Cc:     Pengutronix Kernel Team <kernel@pengutronix.de>,
        Fabio Estevam <festevam@gmail.com>,
        NXP Linux Team <linux-imx@nxp.com>,
        linux-i2c@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org,
        Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
Subject: [PATCH] i2c: mxs: use MXS_DMA_CTRL_WAIT4END instead of DMA_CTRL_ACK
Date:   Fri, 11 Sep 2020 17:01:39 +0200
Message-Id: <20200911150139.13690-1-matthias.schiffer@ew.tq-group.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

The driver-specific usage of the DMA_CTRL_ACK flag was replaced with a
custom flag in commit ceeeb99cd821 ("dmaengine: mxs: rename custom flag"),
but i2c-mxs was not updated to use the new flag, completely breaking I2C
transactions using DMA.

Fixes: ceeeb99cd821 ("dmaengine: mxs: rename custom flag")
Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
---

I'm a bit out of my depth here - I have no idea what these flags are
supposed to do. Looking at ceeeb99cd821, this is what I came up with,
and it fixes I2C communication with multiple devices (an EEPROM and a
PCF85063TP RTC) on one of our i.MX28 boards.

I run-tested this on a 5.4.y kernel; given how little is happening in
these drivers nowadays, I assume that the fix is still valid on newer
kernels...


 drivers/i2c/busses/i2c-mxs.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/i2c/busses/i2c-mxs.c b/drivers/i2c/busses/i2c-mxs.c
index 9587347447f0..c4b08a924461 100644
--- a/drivers/i2c/busses/i2c-mxs.c
+++ b/drivers/i2c/busses/i2c-mxs.c
@@ -25,6 +25,7 @@
 #include <linux/of_device.h>
 #include <linux/dma-mapping.h>
 #include <linux/dmaengine.h>
+#include <linux/dma/mxs-dma.h>
 
 #define DRIVER_NAME "mxs-i2c"
 
@@ -200,7 +201,8 @@ static int mxs_i2c_dma_setup_xfer(struct i2c_adapter *adap,
 		dma_map_sg(i2c->dev, &i2c->sg_io[0], 1, DMA_TO_DEVICE);
 		desc = dmaengine_prep_slave_sg(i2c->dmach, &i2c->sg_io[0], 1,
 					DMA_MEM_TO_DEV,
-					DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+					DMA_PREP_INTERRUPT |
+					MXS_DMA_CTRL_WAIT4END);
 		if (!desc) {
 			dev_err(i2c->dev,
 				"Failed to get DMA data write descriptor.\n");
@@ -228,7 +230,8 @@ static int mxs_i2c_dma_setup_xfer(struct i2c_adapter *adap,
 		dma_map_sg(i2c->dev, &i2c->sg_io[1], 1, DMA_FROM_DEVICE);
 		desc = dmaengine_prep_slave_sg(i2c->dmach, &i2c->sg_io[1], 1,
 					DMA_DEV_TO_MEM,
-					DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+					DMA_PREP_INTERRUPT |
+					MXS_DMA_CTRL_WAIT4END);
 		if (!desc) {
 			dev_err(i2c->dev,
 				"Failed to get DMA data write descriptor.\n");
@@ -260,7 +263,8 @@ static int mxs_i2c_dma_setup_xfer(struct i2c_adapter *adap,
 		dma_map_sg(i2c->dev, i2c->sg_io, 2, DMA_TO_DEVICE);
 		desc = dmaengine_prep_slave_sg(i2c->dmach, i2c->sg_io, 2,
 					DMA_MEM_TO_DEV,
-					DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+					DMA_PREP_INTERRUPT |
+					MXS_DMA_CTRL_WAIT4END);
 		if (!desc) {
 			dev_err(i2c->dev,
 				"Failed to get DMA data write descriptor.\n");
-- 
2.17.1