Lines Matching refs:DMA

2 Linux I2C and DMA
6 transferred are small, it is not considered a prime user of DMA access. At this
7 time of writing, only 10% of I2C bus master drivers have DMA support
9 DMA for it will likely add more overhead than a plain PIO transfer.
11 Therefore, it is *not* mandatory that the buffer of an I2C message is DMA safe.
13 rarely used. However, it is recommended to use a DMA-safe buffer if your
14 message size is likely applicable for DMA. Most drivers have this threshold
18 I2C bus master driver is using USB as a bridge, then you need to have DMA
24 For clients, if you use a DMA safe buffer in i2c_msg, set the I2C_M_DMA_SAFE
25 flag with it. Then, the I2C core and drivers know they can safely operate DMA
28 using an unsafe DMA buffer. To improve this situation, using I2C_M_DMA_SAFE in
32 buffers in kernel space are always DMA capable. Also, when the core emulates
33 SMBus transactions via I2C, the buffers for block transfers are DMA safe. Users
34 of i2c_master_send() and i2c_master_recv() functions can now use DMA safe
36 know their buffers are DMA safe. Users of i2c_transfer() must set the
42 Bus master drivers wishing to implement safe DMA can use helper functions from
43 the I2C core. One gives you a DMA-safe buffer for a given i2c_msg as long as a
59 message or not. No syncing is needed in cases setting up DMA had an error and
69 Final note: If you plan to use DMA with I2C (or with anything else, actually)