[PATCH v4 3/3] i2c: stm32f7: support i2c_*_dma_safe_msg_buf APIs
From: Clément Le Goffic <hidden>
Date: 2025-07-04 08:42:01
Also in:
dri-devel, linux-i2c, linux-media, lkml
Subsystem:
i2c subsystem, i2c subsystem host drivers, st stm32 i2c/smbus driver, the rest · Maintainers:
Andi Shyti, Pierre-Yves MORDRET, Alain Volmat, Linus Torvalds
`i2c_*_dma_safe_msg_buf` APIs operate on a `struct i2c_msg`. The get operation make sure the I2C buffer is DMA'able according to its buffer length, or if the memory use is DMA coherent for example and return a valid pointer for safe DMA access to be used. The put operation release the pointer. Prefer using generic API's than relying on private tests. Acked-by: Alain Volmat <alain.volmat@foss.st.com> Signed-off-by: Clément Le Goffic <redacted> --- drivers/i2c/busses/i2c-stm32f7.c | 32 +++++++++++++++++++++----------- 1 file changed, 21 insertions(+), 11 deletions(-)
diff --git a/drivers/i2c/busses/i2c-stm32f7.c b/drivers/i2c/busses/i2c-stm32f7.c
index 73a7b8894c0d..994232646789 100644
--- a/drivers/i2c/busses/i2c-stm32f7.c
+++ b/drivers/i2c/busses/i2c-stm32f7.c@@ -741,11 +741,14 @@ static void stm32f7_i2c_dma_callback(void *arg) { struct stm32f7_i2c_dev *i2c_dev = arg; struct stm32_i2c_dma *dma = i2c_dev->dma; + struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg; 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); + if (!f7_msg->smbus) + i2c_put_dma_safe_msg_buf(f7_msg->buf, i2c_dev->msg, true); complete(&dma->dma_complete); }
@@ -881,6 +884,7 @@ 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;
@@ -930,17 +934,23 @@ 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) {
--
2.43.0