For clients, if you use a DMA safe buffer in i2c_msg, set the I2C_M_DMA_SAFE flag with it. Then, the I2C core and drivers know they can safely operate DMA on it. Note that using this flag is optional. I2C host drivers which are not updated to use this flag will work like before. And like before, they risk using an unsafe DMA buffer. To improve this situation, using I2C_M_DMA_SAFE in more and more clients and host drivers is the planned way forward. Note also that setting this flag makes only sense in kernel space. User space data is copied into kernel space anyhow. The I2C core makes sure the destination buffers in kernel space are always DMA capable. Also, when the core emulates SMBus transactions via I2C, the buffers for block transfers are DMA safe. Users of i2c_master_send() and i2c_master_recv() functions can now use DMA safe variants (i2c_master_send_dmasafe() and i2c_master_recv_dmasafe()) once they know their buffers are DMA safe. Users of i2c_transfer() must set the I2C_M_DMA_SAFE flag manually.