[PATCH v2 0/3] Fix STM32 I2C dma operations

[PATCH v2 0/3] Fix STM32 I2C dma operations

[Clément Le Goffic]

This patch series aims to fix some issues inside the driver's DMA
handling.
It also uses newer I2C DMA API.

Signed-off-by: Clément Le Goffic <clement.legoffic@foss.st.com>
---
Changes in v2:
- Fix the dev used in dma_unmap also in the error path of
  `stm32_i2c_prep_dma_xfer`
- Add a dma_unmap_single also in the ITs error handler
- Add Alain Volmat's "Acked-by" on patch 3
- Link to v1: https://lore.kernel.org/r/20250616-i2c-upstream-v1-0-42d3d5374e65@foss.st.com

---
Clément Le Goffic (3):
      i2c: stm32: fix the device used for the DMA map
      i2c: stm32f7: unmap DMA mapped buffer
      i2c: stm32f7: support i2c_*_dma_safe_msg_buf APIs

 drivers/i2c/busses/i2c-stm32.c   |  4 ++--
 drivers/i2c/busses/i2c-stm32f7.c | 42 +++++++++++++++++++++++++++++-----------
 2 files changed, 33 insertions(+), 13 deletions(-)
---
base-commit: 86731a2a651e58953fc949573895f2fa6d456841
change-id: 20250527-i2c-upstream-e5b69501359a

Best regards,
--  
Clément Le Goffic <clement.legoffic@foss.st.com>

[PATCH v2 1/3] i2c: stm32: fix the device used for the DMA map

[Clément Le Goffic]

If the DMA mapping failed, it produced an error log with the wrong
device name:
"stm32-dma3 40400000.dma-controller: rejecting DMA map of vmalloc memory"
Fix this issue by replacing the dev with the I2C dev.

Fixes: bb8822cbbc53 ("i2c: i2c-stm32: Add generic DMA API")
Signed-off-by: Clément Le Goffic <clement.legoffic@foss.st.com>
---
 drivers/i2c/busses/i2c-stm32.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-stm32.c b/drivers/i2c/busses/i2c-stm32.c
index 157c64e27d0b..272a5dffb08f 100644
--- a/drivers/i2c/busses/i2c-stm32.c
+++ b/drivers/i2c/busses/i2c-stm32.c
@@ -118,7 +118,7 @@ int stm32_i2c_prep_dma_xfer(struct device *dev, struct stm32_i2c_dma *dma,
 	dma->dma_len = len;
 	chan_dev = dma->chan_using->device->dev;
 
-	dma->dma_buf = dma_map_single(chan_dev, buf, dma->dma_len,
+	dma->dma_buf = dma_map_single(dev, buf, dma->dma_len,
 				      dma->dma_data_dir);
 	if (dma_mapping_error(chan_dev, dma->dma_buf)) {
 		dev_err(dev, "DMA mapping failed\n");
@@ -150,7 +150,7 @@ int stm32_i2c_prep_dma_xfer(struct device *dev, struct stm32_i2c_dma *dma,
 	return 0;
 
 err:
-	dma_unmap_single(chan_dev, dma->dma_buf, dma->dma_len,
+	dma_unmap_single(dev, dma->dma_buf, dma->dma_len,
 			 dma->dma_data_dir);
 	return ret;
 }

-- 
2.43.0

[PATCH v2 2/3] i2c: stm32f7: unmap DMA mapped buffer

[Clément Le Goffic]

Fix an issue where the mapped DMA buffer was not unmapped.

Fixes: 7ecc8cfde553 ("i2c: i2c-stm32f7: Add DMA support")
Signed-off-by: Clément Le Goffic <clement.legoffic@foss.st.com>
---
 drivers/i2c/busses/i2c-stm32f7.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/i2c/busses/i2c-stm32f7.c b/drivers/i2c/busses/i2c-stm32f7.c
index e4aaeb2262d0..042386b4cabe 100644
--- a/drivers/i2c/busses/i2c-stm32f7.c
+++ b/drivers/i2c/busses/i2c-stm32f7.c
@@ -1554,6 +1554,8 @@ static irqreturn_t stm32f7_i2c_handle_isr_errs(struct stm32f7_i2c_dev *i2c_dev,
 	if (i2c_dev->use_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);
 	}
 
 	i2c_dev->master_mode = false;
@@ -1622,6 +1624,8 @@ static irqreturn_t stm32f7_i2c_isr_event_thread(int irq, void *data)
 		if (i2c_dev->use_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);
 		}
 		f7_msg->result = -ENXIO;
 	}
@@ -1642,6 +1646,8 @@ static irqreturn_t stm32f7_i2c_isr_event_thread(int irq, void *data)
 				dev_dbg(i2c_dev->dev, "<%s>: Timed out\n", __func__);
 				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);
 				f7_msg->result = -ETIMEDOUT;
 			}
 		}

-- 
2.43.0

[PATCH v2 3/3] i2c: stm32f7: support i2c_*_dma_safe_msg_buf APIs

[Clément Le Goffic]

Use the i2c-core-base APIs to allocate a DMA safe buffer when needed.

Signed-off-by: Clément Le Goffic <clement.legoffic@foss.st.com>
Acked-by: Alain Volmat <alain.volmat@foss.st.com>
---
 drivers/i2c/busses/i2c-stm32f7.c | 36 +++++++++++++++++++++++++-----------
 1 file changed, 25 insertions(+), 11 deletions(-)

diff --git a/drivers/i2c/busses/i2c-stm32f7.c b/drivers/i2c/busses/i2c-stm32f7.c
index 042386b4cabe..d06f0efdece3 100644
--- a/drivers/i2c/busses/i2c-stm32f7.c
+++ b/drivers/i2c/busses/i2c-stm32f7.c
@@ -742,9 +742,12 @@ static void stm32f7_i2c_dma_callback(void *arg)
 	struct stm32f7_i2c_dev *i2c_dev = (struct stm32f7_i2c_dev *)arg;
 	struct stm32_i2c_dma *dma = i2c_dev->dma;
 	struct device *dev = dma->chan_using->device->dev;
+	struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
 
 	stm32f7_i2c_disable_dma_req(i2c_dev);
 	dma_unmap_single(dev, dma->dma_buf, dma->dma_len, dma->dma_data_dir);
+	if (!f7_msg->smbus)
+		i2c_put_dma_safe_msg_buf(f7_msg->buf, i2c_dev->msg, true);
 	complete(&dma->dma_complete);
 }
 
@@ -880,6 +883,7 @@ static void stm32f7_i2c_xfer_msg(struct stm32f7_i2c_dev *i2c_dev,
 {
 	struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
 	void __iomem *base = i2c_dev->base;
+	u8 *dma_buf;
 	u32 cr1, cr2;
 	int ret;
 
@@ -929,17 +933,23 @@ static void stm32f7_i2c_xfer_msg(struct stm32f7_i2c_dev *i2c_dev,
 
 	/* Configure DMA or enable RX/TX interrupt */
 	i2c_dev->use_dma = false;
-	if (i2c_dev->dma && f7_msg->count >= STM32F7_I2C_DMA_LEN_MIN
-	    && !i2c_dev->atomic) {
-		ret = stm32_i2c_prep_dma_xfer(i2c_dev->dev, i2c_dev->dma,
-					      msg->flags & I2C_M_RD,
-					      f7_msg->count, f7_msg->buf,
-					      stm32f7_i2c_dma_callback,
-					      i2c_dev);
-		if (!ret)
-			i2c_dev->use_dma = true;
-		else
-			dev_warn(i2c_dev->dev, "can't use DMA\n");
+	if (i2c_dev->dma && !i2c_dev->atomic) {
+		dma_buf = i2c_get_dma_safe_msg_buf(msg, STM32F7_I2C_DMA_LEN_MIN);
+		if (dma_buf) {
+			f7_msg->buf = dma_buf;
+			ret = stm32_i2c_prep_dma_xfer(i2c_dev->dev, i2c_dev->dma,
+						      msg->flags & I2C_M_RD,
+						      f7_msg->count, f7_msg->buf,
+						      stm32f7_i2c_dma_callback,
+						      i2c_dev);
+			if (ret) {
+				dev_warn(i2c_dev->dev, "can't use DMA\n");
+				i2c_put_dma_safe_msg_buf(f7_msg->buf, msg, false);
+				f7_msg->buf = msg->buf;
+			} else {
+				i2c_dev->use_dma = true;
+			}
+		}
 	}
 
 	if (!i2c_dev->use_dma) {
@@ -1626,6 +1636,8 @@ static irqreturn_t stm32f7_i2c_isr_event_thread(int irq, void *data)
 			dmaengine_terminate_async(dma->chan_using);
 			dma_unmap_single(i2c_dev->dev, dma->dma_buf, dma->dma_len,
 					 dma->dma_data_dir);
+			if (!f7_msg->smbus)
+				i2c_put_dma_safe_msg_buf(f7_msg->buf, i2c_dev->msg, false);
 		}
 		f7_msg->result = -ENXIO;
 	}
@@ -1648,6 +1660,8 @@ static irqreturn_t stm32f7_i2c_isr_event_thread(int irq, void *data)
 				dmaengine_terminate_async(dma->chan_using);
 				dma_unmap_single(i2c_dev->dev, dma->dma_buf, dma->dma_len,
 						 dma->dma_data_dir);
+				if (!f7_msg->smbus)
+					i2c_put_dma_safe_msg_buf(f7_msg->buf, i2c_dev->msg, false);
 				f7_msg->result = -ETIMEDOUT;
 			}
 		}

-- 
2.43.0

Re: [PATCH v2 1/3] i2c: stm32: fix the device used for the DMA map

[Alain Volmat]

Hello Clément,

On Fri, Jun 27, 2025 at 12:12:56PM +0200, Clément Le Goffic wrote:
> If the DMA mapping failed, it produced an error log with the wrong
> device name:
> "stm32-dma3 40400000.dma-controller: rejecting DMA map of vmalloc memory"
> Fix this issue by replacing the dev with the I2C dev.
> 
> Fixes: bb8822cbbc53 ("i2c: i2c-stm32: Add generic DMA API")
> Signed-off-by: Clément Le Goffic <clement.legoffic@foss.st.com>
> ---
>  drivers/i2c/busses/i2c-stm32.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-stm32.c b/drivers/i2c/busses/i2c-stm32.c
> index 157c64e27d0b..272a5dffb08f 100644
> --- a/drivers/i2c/busses/i2c-stm32.c
> +++ b/drivers/i2c/busses/i2c-stm32.c
> @@ -118,7 +118,7 @@ int stm32_i2c_prep_dma_xfer(struct device *dev, struct stm32_i2c_dma *dma,
>  	dma->dma_len = len;
>  	chan_dev = dma->chan_using->device->dev;
>  
> -	dma->dma_buf = dma_map_single(chan_dev, buf, dma->dma_len,
> +	dma->dma_buf = dma_map_single(dev, buf, dma->dma_len,
>  				      dma->dma_data_dir);
>  	if (dma_mapping_error(chan_dev, dma->dma_buf)) {
>  		dev_err(dev, "DMA mapping failed\n");
> @@ -150,7 +150,7 @@ int stm32_i2c_prep_dma_xfer(struct device *dev, struct stm32_i2c_dma *dma,
>  	return 0;
>  
>  err:
> -	dma_unmap_single(chan_dev, dma->dma_buf, dma->dma_len,
> +	dma_unmap_single(dev, dma->dma_buf, dma->dma_len,
>  			 dma->dma_data_dir);
>  	return ret;
>  }
> 

Thanks for the v2.

Acked-by: Alain Volmat <alain.volmat@foss.st.com>

Regards,
Alain

> -- 
> 2.43.0
> 

Re: [PATCH v2 2/3] i2c: stm32f7: unmap DMA mapped buffer

[Alain Volmat]

Hello Clément,

On Fri, Jun 27, 2025 at 12:12:57PM +0200, Clément Le Goffic wrote:
> Fix an issue where the mapped DMA buffer was not unmapped.
> 
> Fixes: 7ecc8cfde553 ("i2c: i2c-stm32f7: Add DMA support")
> Signed-off-by: Clément Le Goffic <clement.legoffic@foss.st.com>
> ---
>  drivers/i2c/busses/i2c-stm32f7.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/i2c/busses/i2c-stm32f7.c b/drivers/i2c/busses/i2c-stm32f7.c
> index e4aaeb2262d0..042386b4cabe 100644
> --- a/drivers/i2c/busses/i2c-stm32f7.c
> +++ b/drivers/i2c/busses/i2c-stm32f7.c
> @@ -1554,6 +1554,8 @@ static irqreturn_t stm32f7_i2c_handle_isr_errs(struct stm32f7_i2c_dev *i2c_dev,
>  	if (i2c_dev->use_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);
>  	}
>  
>  	i2c_dev->master_mode = false;
> @@ -1622,6 +1624,8 @@ static irqreturn_t stm32f7_i2c_isr_event_thread(int irq, void *data)
>  		if (i2c_dev->use_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);
>  		}
>  		f7_msg->result = -ENXIO;
>  	}
> @@ -1642,6 +1646,8 @@ static irqreturn_t stm32f7_i2c_isr_event_thread(int irq, void *data)
>  				dev_dbg(i2c_dev->dev, "<%s>: Timed out\n", __func__);
>  				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);
>  				f7_msg->result = -ETIMEDOUT;
>  			}
>  		}
> 

Thanks for the update. Looks good to me.

Acked-by: Alain Volmat <alain.volmat@foss.st.com>

Regards,
Alain

> -- 
> 2.43.0
>