The ASRC supports polling, interrupt and DMA modes, but only DMA mode is used in
the platform for better performance. The ASRC supports the following DMA channels:
• Peripheral to peripheral, for example: ASRC to ESAI
• Memory to peripheral, for example: memory to ASRC
• Peripheral to memory, for example: ASRC to memory
For more information, see the chapter on ASRC in the Multimedia Applications
Processor documentation.
26.2 Software Operation
As an assistant component in the audio system, the ASRC driver implementation depends
on the use cases in the platform.
Currently ASRC is used in following two scenarios:
• Memory > ASRC > Memory, ASRC is controlled by user application or ALSA plug-
in.
• Memory > ASRC > peripheral, ASRC is controlled directly by other ALSA driver.
Figure 26-1. Audio Driver Interactions
As illustrated in figure above, the ASRC stream interface provides the interface for the
user space. The ASRC registers itself under /dev/mxc_asrc and creates proc file /proc/
driver/asrc when the module is inserted. proc is used to track the channel number for each
Software Operation
i.MX 6Solo/6DualLite Linux Reference Manual, Rev. L3.0.35_4.1.0, 09/2013
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Freescale Semiconductor, Inc.
