keep the scatterlist mapped until the DMA operation has completed.
The scatterlist must be mapped using the DMA struct device.
If a mapping needs to be synchronized later, dma_sync_*_for_*() must be
keep the scatterlist mapped until the DMA operation has completed.
The scatterlist must be mapped using the DMA struct device.
If a mapping needs to be synchronized later, dma_sync_*_for_*() must be