Hi Frank,

On Tue, Nov 03, 2026 at 04:26:54PM -0500, Frank.Li@oss.nxp.com wrote:

From: Frank Li Frank.Li@nxp.com

Replace direct dma_chan::device::dev access with the proper dmaengine_get_dma_device() for consumer API.

chan->device->dev is not always the device used for DMA mapping. Some DMA engines support per-channel IOMMU mappings, so different channels may use different DMA devices. dmaengine_get_dma_device() returns the correct device for each channel.

This also prepares for making the DMA engine provider data structures private. DMA consumers should not access DMA engine internals directly.

Thanks for this, looks useful.

• dma_addr = dma_map_single(chan->device->dev, buf, len, dir);
• if (dma_mapping_error(chan->device->dev, dma_addr)) {

• dma_addr = dma_map_single(dmaengine_get_dma_device(chan), buf, len, dir);
• if (dma_mapping_error(dmaengine_get_dma_device(chan), dma_addr)) { dev_dbg(dev, "dma map failed, using PIO\n");

I think we should populate a dma_dev-variable here and reuse it instead of calling dmaengine_get_dma_device() twice.

Happy hacking,

Wolfram