[PATCH v4 2/3] i2c: stm32f7: unmap DMA mapped buffer

Clément Le Goffic
2025-07-04T08:42:05Z

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")
Acked-by: Alain Volmat <alain.volmat@foss.st.com>
Signed-off-by: Clément Le Goffic <clement.legoffic@foss.st.com>
---
drivers/i2c/busses/i2c-stm32f7.c | 20 +++++++-------------
1 file changed, 7 insertions(+), 13 deletions(-)

diff --git a/drivers/i2c/busses/i2c-stm32f7.c b/drivers/i2c/busses/i2c-stm32f7.c
index 817d081460c2..73a7b8894c0d 100644
--- 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(struct stm32f7_i2c_dev *i2c_dev)

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_isr_errs(struct stm32f7_i2c_dev *i2c_dev,
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_isr_errs(struct stm32f7_i2c_dev *i2c_dev,
}

/* 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_thread(int irq, void *data)
{
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_thread(int irq, void *data)
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_thread(int irq, void *data)
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;
}
}

--
2.43.0