Hi Clément,
thanks for the patch.
On Mon, Jun 16, 2025 at 10:53:56AM +0200, Clément Le Goffic wrote:
> Use the i2c-core-base APIs to allocate a DMA safe buffer when needed.
>
> Signed-off-by: Clément Le Goffic <clement.legof...@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 a05cac5ee9db..5be14c8a2af4 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) {
> @@ -1624,6 +1634,8 @@ 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;
> }
> @@ -1646,6 +1658,8 @@ 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;
> }
> }
>
Looks good to me.
Acked-by: Alain Volmat <alain.vol...@foss.st.com>
Regards,
Alain
> --
> 2.43.0
>
