• Allocates a free substream for the operation to be performed.
• Opens the low-level hardware device.
• Assigns the hardware capabilities to ALSA runtime information (the runtime
structure contains all the hardware, DMA, and software capabilities of an opened
substream).
• Configures DMA read or write channel for operation.
• Configures CPU DAI and CODEC DAI interface.
• Configures CODEC hardware.
• Triggers the transfer.
After triggering for the first time, the subsequent DMA read/write operations are
configured by the DMA callback.
25.4.4 Platform Data
struct mxc_audio_platform_data defined in include/linux/fsl_devices.h is used to pass the
platform data of audio CODEC.
The value of platform data needs to be updated according to Hardware design.
Take wm8962 CODEC platform data as a example to show the parameter of
mxc_audio_platform_data. See header file for the details of more variables.
•
ssi_num
indicates which SSI channel is used.
•
src_port
indicates which AUDMUX port is connected with SSI.
•
ext_port
indicates which AUDMUX port is connected with external audio CODEC.
•
hp_gpio
: The IRQ line used for headphone detection.
•
hp_active_low
: When headphone is inserted, the detection pin status. If pin voltage
level is low, the value should be 1.
•
mic_gpio
: The IRQ line used for micphone detection
•
mic_active_low
: When micphone is inserted, the detection pin status, if pin voltage
level is low, the value should be 1.
•
init
: The callback function to initialize audio CODEC. For example, configure the
clock of audio CODEC.
•
clock_enable
: The callback function to enable or disable clock for audio CODEC.
25.4.5 Menu Configuration Options
The following Linux kernel configuration options are provided for this module:
Software Operation
i.MX 6Solo/6DualLite Linux Reference Manual, Rev. L3.0.35_4.1.0, 09/2013
186
Freescale Semiconductor, Inc.
