[PATCH 02/12] media: stm32: dcmi: perform dmaengine_slave_config at probe

Alain Volmat
2025-12-18T18:45:11Z

Perform the dma channel configuration at probe time right after
the channel allocation since this is fixed for the whole lifetime
of the driver.

Signed-off-by: Alain Volmat <alain.volmat@foss.st.com>
---
drivers/media/platform/st/stm32/stm32-dcmi.c | 32 +++++++++++++---------------
1 file changed, 15 insertions(+), 17 deletions(-)

diff --git a/drivers/media/platform/st/stm32/stm32-dcmi.c b/drivers/media/platform/st/stm32/stm32-dcmi.c
index 07b67eb5b9dd..27b283474096 100644
--- a/drivers/media/platform/st/stm32/stm32-dcmi.c
+++ b/drivers/media/platform/st/stm32/stm32-dcmi.c
@@ -301,23 +301,6 @@ static int dcmi_start_dma(struct stm32_dcmi *dcmi,
struct dcmi_buf *buf)
{
struct dma_async_tx_descriptor *desc = NULL;
- struct dma_slave_config config;
- int ret;
-
- memset(&config, 0, sizeof(config));
-
- config.src_addr = (dma_addr_t)dcmi->res->start + DCMI_DR;
- config.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
- config.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
- config.dst_maxburst = 4;
-
- /* Configure DMA channel */
- ret = dmaengine_slave_config(dcmi->dma_chan, &config);
- if (ret < 0) {
- dev_err(dcmi->dev, "%s: DMA channel config failed (%d)\n",
- __func__, ret);
- return ret;
- }

/*
* Avoid call of dmaengine_terminate_sync() between
@@ -1888,6 +1871,7 @@ static int dcmi_probe(struct platform_device *pdev)
struct vb2_queue *q;
struct dma_chan *chan;
struct dma_slave_caps caps;
+ struct dma_slave_config dma_config;
struct clk *mclk;
int ret = 0;

@@ -1954,6 +1938,19 @@ static int dcmi_probe(struct platform_device *pdev)
if (!ret && caps.max_sg_burst)
dcmi->dma_max_burst = caps.max_sg_burst * DMA_SLAVE_BUSWIDTH_4_BYTES;

+ memset(&dma_config, 0, sizeof(dma_config));
+
+ dma_config.src_addr = (dma_addr_t)dcmi->res->start + DCMI_DR;
+ dma_config.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
+
+ /* Configure DMA channel */
+ ret = dmaengine_slave_config(chan, &dma_config);
+ if (ret < 0) {
+ dev_err(dcmi->dev, "%s: DMA channel config failed (%d)\n",
+ __func__, ret);
+ goto err_dma_slave_config;
+ }
+
spin_lock_init(&dcmi->irqlock);
mutex_init(&dcmi->lock);
mutex_init(&dcmi->dma_lock);
@@ -2072,6 +2069,7 @@ static int dcmi_probe(struct platform_device *pdev)
v4l2_device_unregister(&dcmi->v4l2_dev);
err_media_device_cleanup:
media_device_cleanup(&dcmi->mdev);
+err_dma_slave_config:
dma_release_channel(dcmi->dma_chan);

return ret;

--
2.34.1