256 lines
6.5 KiB
Plaintext
256 lines
6.5 KiB
Plaintext
Renesas R-Car sound
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=============================================
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* Modules
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=============================================
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Renesas R-Car and RZ/G sound is constructed from below modules
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(for Gen2 or later)
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SCU : Sampling Rate Converter Unit
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- SRC : Sampling Rate Converter
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- CMD
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- CTU : Channel Transfer Unit
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- MIX : Mixer
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- DVC : Digital Volume and Mute Function
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SSIU : Serial Sound Interface Unit
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SSI : Serial Sound Interface
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See detail of each module's channels, connection, limitation on datasheet
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=============================================
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* Multi channel
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=============================================
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Multi channel is supported by Multi-SSI, or TDM-SSI.
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Multi-SSI : 6ch case, you can use stereo x 3 SSI
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TDM-SSI : 6ch case, you can use TDM
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=============================================
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* Enable/Disable each modules
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=============================================
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See datasheet to check SRC/CTU/MIX/DVC connect-limitation.
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DT controls enabling/disabling module.
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${LINUX}/arch/arm/boot/dts/r8a7790-lager.dts can be good example.
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This is example of
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Playback: [MEM] -> [SRC2] -> [DVC0] -> [SSIU0/SSI0] -> [codec]
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Capture: [MEM] <- [DVC1] <- [SRC3] <- [SSIU1/SSI1] <- [codec]
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see "Example: simple sound card"
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You can use below.
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${LINUX}/arch/arm/boot/dts/r8a7790.dts can be good example.
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&src0 &ctu00 &mix0 &dvc0 &ssi0
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&src1 &ctu01 &mix1 &dvc1 &ssi1
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&src2 &ctu02 &ssi2
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&src3 &ctu03 &ssi3
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&src4 &ssi4
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&src5 &ctu10 &ssi5
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&src6 &ctu11 &ssi6
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&src7 &ctu12 &ssi7
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&src8 &ctu13 &ssi8
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&src9 &ssi9
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=============================================
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* SRC (Sampling Rate Converter)
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=============================================
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[xx]Hz [yy]Hz
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------> [SRC] ------>
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SRC can convert [xx]Hz to [yy]Hz. Then, it has below 2 modes
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Asynchronous mode: input data / output data are based on different clocks.
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you can use this mode on Playback / Capture
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Synchronous mode: input data / output data are based on same clocks.
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This mode will be used if system doesn't have its input clock,
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for example digital TV case.
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you can use this mode on Playback
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------------------
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** Asynchronous mode
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------------------
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You need to use "simple-scu-audio-card" or "audio-graph-scu-card" for it.
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see "Example: simple sound card for Asynchronous mode"
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------------------
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** Synchronous mode
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------------------
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> amixer set "SRC Out Rate" on
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> aplay xxxx.wav
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> amixer set "SRC Out Rate" 48000
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> amixer set "SRC Out Rate" 44100
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=============================================
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* CTU (Channel Transfer Unit)
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=============================================
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[xx]ch [yy]ch
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------> [CTU] -------->
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CTU can convert [xx]ch to [yy]ch, or exchange outputed channel.
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CTU conversion needs matrix settings.
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For more detail information, see below
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Renesas R-Car datasheet
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- Sampling Rate Converter Unit (SCU)
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- SCU Operation
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- CMD Block
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- Functional Blocks in CMD
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Renesas R-Car datasheet
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- Sampling Rate Converter Unit (SCU)
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- Register Description
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- CTUn Scale Value exx Register (CTUn_SVxxR)
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${LINUX}/sound/soc/sh/rcar/ctu.c
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- comment of header
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You need to use "simple-scu-audio-card" or "audio-graph-scu-card" for it.
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see "Example: simple sound card for channel convert"
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Ex) Exchange output channel
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Input -> Output
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1ch -> 0ch
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0ch -> 1ch
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example of using matrix
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output 0ch = (input 0ch x 0) + (input 1ch x 1)
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output 1ch = (input 0ch x 1) + (input 1ch x 0)
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amixer set "CTU Reset" on
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amixer set "CTU Pass" 9,10
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amixer set "CTU SV0" 0,4194304
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amixer set "CTU SV1" 4194304,0
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example of changing connection
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amixer set "CTU Reset" on
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amixer set "CTU Pass" 2,1
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=============================================
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* MIX (Mixer)
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=============================================
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MIX merges 2 sounds path. You can see 2 sound interface on system,
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and these sounds will be merged by MIX.
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aplay -D plughw:0,0 xxxx.wav &
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aplay -D plughw:0,1 yyyy.wav
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You need to use "simple-scu-audio-card" or "audio-graph-scu-card" for it.
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Ex)
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[MEM] -> [SRC1] -> [CTU02] -+-> [MIX0] -> [DVC0] -> [SSI0]
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[MEM] -> [SRC2] -> [CTU03] -+
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see "Example: simple sound card for MIXer"
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=============================================
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* DVC (Digital Volume and Mute Function)
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=============================================
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DVC controls Playback/Capture volume.
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Playback Volume
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amixer set "DVC Out" 100%
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Capture Volume
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amixer set "DVC In" 100%
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Playback Mute
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amixer set "DVC Out Mute" on
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Capture Mute
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amixer set "DVC In Mute" on
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Volume Ramp
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amixer set "DVC Out Ramp Up Rate" "0.125 dB/64 steps"
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amixer set "DVC Out Ramp Down Rate" "0.125 dB/512 steps"
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amixer set "DVC Out Ramp" on
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aplay xxx.wav &
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amixer set "DVC Out" 80% // Volume Down
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amixer set "DVC Out" 100% // Volume Up
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=============================================
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* SSIU (Serial Sound Interface Unit)
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=============================================
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SSIU can avoid some under/over run error, because it has some buffer.
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But you can't use it if SSI was PIO mode.
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In DMA mode, you can select not to use SSIU by using "no-busif" via SSI.
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SSIU handles BUSIF which will be used for TDM Split mode.
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This driver is assuming that audio-graph card will be used.
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TDM Split mode merges 4 sounds. You can see 4 sound interface on system,
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and these sounds will be merged SSIU/SSI.
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aplay -D plughw:0,0 xxxx.wav &
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aplay -D plughw:0,1 xxxx.wav &
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aplay -D plughw:0,2 xxxx.wav &
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aplay -D plughw:0,3 xxxx.wav
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2ch 8ch
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[MEM] -> [SSIU 30] -+-> [SSIU 3] --> [Codec]
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2ch |
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[MEM] -> [SSIU 31] -+
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2ch |
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[MEM] -> [SSIU 32] -+
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2ch |
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[MEM] -> [SSIU 33] -+
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see "Example: simple sound card for TDM Split"
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=============================================
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* SSI (Serial Sound Interface)
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=============================================
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** PIO mode
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You can use PIO mode which is for connection check by using.
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Note: The system will drop non-SSI modules in PIO mode
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even though if DT is selecting other modules.
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&ssi0 {
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pio-transfer
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};
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** DMA mode without SSIU
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You can use DMA without SSIU.
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Note: under/over run, or noise are likely to occur
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&ssi0 {
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no-busif;
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};
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** PIN sharing
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Each SSI can share WS pin. It is based on platform.
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This is example if SSI1 want to share WS pin with SSI0
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&ssi1 {
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shared-pin;
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};
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** Multi-SSI
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You can use Multi-SSI.
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This is example of SSI0/SSI1/SSI2 (= for 6ch)
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see "Example: simple sound card for Multi channel"
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** TDM-SSI
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You can use TDM with SSI.
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This is example of TDM 6ch.
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Driver can automatically switches TDM <-> stereo mode in this case.
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see "Example: simple sound card for TDM"
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