releases/6.15.8/i2c-stm32f7-unmap-dma-mapped-buffer.patch

From 6aae87fe7f180cd93a74466cdb6cf2aa9bb28798 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Cl=C3=A9ment=20Le=20Goffic?= <clement.legoffic@foss.st.com>
Date: Fri, 4 Jul 2025 10:39:15 +0200
Subject: i2c: stm32f7: unmap DMA mapped buffer
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From: Clément Le Goffic <clement.legoffic@foss.st.com>

commit 6aae87fe7f180cd93a74466cdb6cf2aa9bb28798 upstream.

Before each I2C transfer using DMA, the I2C buffer is DMA'pped to make
sure the memory buffer is DMA'able. This is handle in the function
`stm32_i2c_prep_dma_xfer()`.
If the transfer fails for any reason the I2C buffer must be unmap.
Use the dma_callback to factorize the code and fix this issue.

Note that the `stm32f7_i2c_dma_callback()` is now called in case of DMA
transfer success and error and that the `complete()` on the dma_complete
completion structure is done inconditionnally in case of transfer
success or error as well as the `dmaengine_terminate_async()`.
This is allowed as a `complete()` in case transfer error has no effect
as well as a `dmaengine_terminate_async()` on a transfer success.

Also fix the unneeded cast and remove not more needed variables.

Fixes: 7ecc8cfde553 ("i2c: i2c-stm32f7: Add DMA support")
Signed-off-by: Clément Le Goffic <clement.legoffic@foss.st.com>
Cc: <stable@vger.kernel.org> # v4.18+
Acked-by: Alain Volmat <alain.volmat@foss.st.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20250704-i2c-upstream-v4-2-84a095a2c728@foss.st.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/i2c/busses/i2c-stm32f7.c |   20 +++++++-------------
 1 file changed, 7 insertions(+), 13 deletions(-)

--- a/drivers/i2c/busses/i2c-stm32f7.c
+++ b/drivers/i2c/busses/i2c-stm32f7.c
@@ -739,10 +739,11 @@ static void stm32f7_i2c_disable_dma_req(
 
 static void stm32f7_i2c_dma_callback(void *arg)
 {
-	struct stm32f7_i2c_dev *i2c_dev = (struct stm32f7_i2c_dev *)arg;
+	struct stm32f7_i2c_dev *i2c_dev = arg;
 	struct stm32_i2c_dma *dma = i2c_dev->dma;
 
 	stm32f7_i2c_disable_dma_req(i2c_dev);
+	dmaengine_terminate_async(dma->chan_using);
 	dma_unmap_single(i2c_dev->dev, dma->dma_buf, dma->dma_len,
 			 dma->dma_data_dir);
 	complete(&dma->dma_complete);
@@ -1510,7 +1511,6 @@ static irqreturn_t stm32f7_i2c_handle_is
 	u16 addr = f7_msg->addr;
 	void __iomem *base = i2c_dev->base;
 	struct device *dev = i2c_dev->dev;
-	struct stm32_i2c_dma *dma = i2c_dev->dma;
 
 	/* Bus error */
 	if (status & STM32F7_I2C_ISR_BERR) {
@@ -1551,10 +1551,8 @@ static irqreturn_t stm32f7_i2c_handle_is
 	}
 
 	/* Disable dma */
-	if (i2c_dev->use_dma) {
-		stm32f7_i2c_disable_dma_req(i2c_dev);
-		dmaengine_terminate_async(dma->chan_using);
-	}
+	if (i2c_dev->use_dma)
+		stm32f7_i2c_dma_callback(i2c_dev);
 
 	i2c_dev->master_mode = false;
 	complete(&i2c_dev->complete);
@@ -1600,7 +1598,6 @@ static irqreturn_t stm32f7_i2c_isr_event
 {
 	struct stm32f7_i2c_dev *i2c_dev = data;
 	struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
-	struct stm32_i2c_dma *dma = i2c_dev->dma;
 	void __iomem *base = i2c_dev->base;
 	u32 status, mask;
 	int ret;
@@ -1619,10 +1616,8 @@ static irqreturn_t stm32f7_i2c_isr_event
 		dev_dbg(i2c_dev->dev, "<%s>: Receive NACK (addr %x)\n",
 			__func__, f7_msg->addr);
 		writel_relaxed(STM32F7_I2C_ICR_NACKCF, base + STM32F7_I2C_ICR);
-		if (i2c_dev->use_dma) {
-			stm32f7_i2c_disable_dma_req(i2c_dev);
-			dmaengine_terminate_async(dma->chan_using);
-		}
+		if (i2c_dev->use_dma)
+			stm32f7_i2c_dma_callback(i2c_dev);
 		f7_msg->result = -ENXIO;
 	}
 
@@ -1640,8 +1635,7 @@ static irqreturn_t stm32f7_i2c_isr_event
 			ret = wait_for_completion_timeout(&i2c_dev->dma->dma_complete, HZ);
 			if (!ret) {
 				dev_dbg(i2c_dev->dev, "<%s>: Timed out\n", __func__);
-				stm32f7_i2c_disable_dma_req(i2c_dev);
-				dmaengine_terminate_async(dma->chan_using);
+				stm32f7_i2c_dma_callback(i2c_dev);
 				f7_msg->result = -ETIMEDOUT;
 			}
 		}