renesas,rsnd.txt

  1Renesas R-Car sound
  2
  3=============================================
  4* Modules
  5=============================================
  6
  7Renesas R-Car and RZ/G sound is constructed from below modules
  8(for Gen2 or later)
  9
 10 SCU		: Sampling Rate Converter Unit
 11  - SRC		: Sampling Rate Converter
 12  - CMD
 13   - CTU	: Channel Transfer Unit
 14   - MIX	: Mixer
 15   - DVC	: Digital Volume and Mute Function
 16 SSIU		: Serial Sound Interface Unit
 17 SSI		: Serial Sound Interface
 18
 19See detail of each module's channels, connection, limitation on datasheet
 20
 21=============================================
 22* Multi channel
 23=============================================
 24
 25Multi channel is supported by Multi-SSI, or TDM-SSI.
 26
 27 Multi-SSI	: 6ch case, you can use stereo x 3 SSI
 28 TDM-SSI	: 6ch case, you can use TDM
 29
 30=============================================
 31* Enable/Disable each modules
 32=============================================
 33
 34See datasheet to check SRC/CTU/MIX/DVC connect-limitation.
 35DT controls enabling/disabling module.
 36${LINUX}/arch/arm/boot/dts/r8a7790-lager.dts can be good example.
 37This is example of
 38
 39Playback: [MEM] -> [SRC2] -> [DVC0] -> [SSIU0/SSI0] -> [codec]
 40Capture:  [MEM] <- [DVC1] <- [SRC3] <- [SSIU1/SSI1] <- [codec]
 41
 42see "Example: simple sound card"
 43
 44You can use below.
 45${LINUX}/arch/arm/boot/dts/r8a7790.dts can be good example.
 46
 47	&src0	&ctu00	&mix0	&dvc0	&ssi0
 48	&src1	&ctu01	&mix1	&dvc1	&ssi1
 49	&src2	&ctu02			&ssi2
 50	&src3	&ctu03			&ssi3
 51	&src4				&ssi4
 52	&src5	&ctu10			&ssi5
 53	&src6	&ctu11			&ssi6
 54	&src7	&ctu12			&ssi7
 55	&src8	&ctu13			&ssi8
 56	&src9				&ssi9
 57
 58=============================================
 59* SRC (Sampling Rate Converter)
 60=============================================
 61
 62 [xx]Hz        [yy]Hz
 63 ------> [SRC] ------>
 64
 65SRC can convert [xx]Hz to [yy]Hz. Then, it has below 2 modes
 66
 67 Asynchronous mode:	input data / output data are based on different clocks.
 68			you can use this mode on Playback / Capture
 69 Synchronous mode:	input data / output data are based on same clocks.
 70			This mode will be used if system doesn't have its input clock,
 71			for example digital TV case.
 72			you can use this mode on Playback
 73
 74------------------
 75**     Asynchronous mode
 76------------------
 77
 78You need to use "simple-scu-audio-card" or "audio-graph-scu-card" for it.
 79see "Example: simple sound card for Asynchronous mode"
 80
 81------------------
 82**     Synchronous mode
 83------------------
 84
 85	> amixer set "SRC Out Rate" on
 86	> aplay xxxx.wav
 87	> amixer set "SRC Out Rate" 48000
 88	> amixer set "SRC Out Rate" 44100
 89
 90=============================================
 91* CTU (Channel Transfer Unit)
 92=============================================
 93
 94 [xx]ch        [yy]ch
 95 ------> [CTU] -------->
 96
 97CTU can convert [xx]ch to [yy]ch, or exchange outputted channel.
 98CTU conversion needs matrix settings.
 99For more detail information, see below
100
101	Renesas R-Car datasheet
102	 - Sampling Rate Converter Unit (SCU)
103	  - SCU Operation
104	   - CMD Block
105	    - Functional Blocks in CMD
106
107	Renesas R-Car datasheet
108	 - Sampling Rate Converter Unit (SCU)
109	  - Register Description
110	   - CTUn Scale Value exx Register (CTUn_SVxxR)
111
112	${LINUX}/sound/soc/renesas/rcar/ctu.c
113	 - comment of header
114
115You need to use "simple-scu-audio-card" or "audio-graph-scu-card" for it.
116see "Example: simple sound card for channel convert"
117
118Ex) Exchange output channel
119 Input -> Output
120  1ch  ->  0ch
121  0ch  ->  1ch
122
123  example of using matrix
124	output 0ch = (input 0ch x 0) + (input 1ch x 1)
125	output 1ch = (input 0ch x 1) + (input 1ch x 0)
126
127	amixer set "CTU Reset" on
128	amixer set "CTU Pass" 9,10
129	amixer set "CTU SV0" 0,4194304
130	amixer set "CTU SV1" 4194304,0
131
132 example of changing connection
133	amixer set "CTU Reset" on
134	amixer set "CTU Pass" 2,1
135
136=============================================
137* MIX (Mixer)
138=============================================
139
140MIX merges 2 sounds path. You can see 2 sound interface on system,
141and these sounds will be merged by MIX.
142
143	aplay -D plughw:0,0 xxxx.wav &
144	aplay -D plughw:0,1 yyyy.wav
145
146You need to use "simple-scu-audio-card" or "audio-graph-scu-card" for it.
147Ex)
148	[MEM] -> [SRC1] -> [CTU02] -+-> [MIX0] -> [DVC0] -> [SSI0]
149	                            |
150	[MEM] -> [SRC2] -> [CTU03] -+
151
152see "Example: simple sound card for MIXer"
153
154=============================================
155* DVC (Digital Volume and Mute Function)
156=============================================
157
158DVC controls Playback/Capture volume.
159
160Playback Volume
161	amixer set "DVC Out" 100%
162
163Capture Volume
164	amixer set "DVC In" 100%
165
166Playback Mute
167	amixer set "DVC Out Mute" on
168
169Capture Mute
170	amixer set "DVC In Mute" on
171
172Volume Ramp
173	amixer set "DVC Out Ramp Up Rate"   "0.125 dB/64 steps"
174	amixer set "DVC Out Ramp Down Rate" "0.125 dB/512 steps"
175	amixer set "DVC Out Ramp" on
176	aplay xxx.wav &
177	amixer set "DVC Out"  80%  // Volume Down
178	amixer set "DVC Out" 100%  // Volume Up
179
180=============================================
181* SSIU (Serial Sound Interface Unit)
182=============================================
183
184SSIU can avoid some under/over run error, because it has some buffer.
185But you can't use it if SSI was PIO mode.
186In DMA mode, you can select not to use SSIU by using "no-busif" via SSI.
187
188SSIU handles BUSIF which will be used for TDM Split mode.
189This driver is assuming that audio-graph card will be used.
190
191TDM Split mode merges 4 sounds. You can see 4 sound interface on system,
192and these sounds will be merged SSIU/SSI.
193
194	aplay -D plughw:0,0 xxxx.wav &
195	aplay -D plughw:0,1 xxxx.wav &
196	aplay -D plughw:0,2 xxxx.wav &
197	aplay -D plughw:0,3 xxxx.wav
198
199	          2ch                     8ch
200	[MEM] -> [SSIU 30] -+-> [SSIU 3] --> [Codec]
201	          2ch       |
202	[MEM] -> [SSIU 31] -+
203	          2ch       |
204	[MEM] -> [SSIU 32] -+
205	          2ch       |
206	[MEM] -> [SSIU 33] -+
207
208see "Example: simple sound card for TDM Split"
209
210=============================================
211* SSI (Serial Sound Interface)
212=============================================
213
214**  PIO mode
215
216You can use PIO mode which is for connection check by using.
217Note: The system will drop non-SSI modules in PIO mode
218even though if DT is selecting other modules.
219
220	&ssi0 {
221		pio-transfer
222	};
223
224** DMA mode without SSIU
225
226You can use DMA without SSIU.
227Note: under/over run, or noise are likely to occur
228
229	&ssi0 {
230		no-busif;
231	};
232
233** PIN sharing
234
235Each SSI can share WS pin. It is based on platform.
236This is example if SSI1 want to share WS pin with SSI0
237
238	&ssi1 {
239		shared-pin;
240	};
241
242** Multi-SSI
243
244You can use Multi-SSI.
245This is example of SSI0/SSI1/SSI2 (= for 6ch)
246
247see "Example: simple sound card for Multi channel"
248
249** TDM-SSI
250
251You can use TDM with SSI.
252This is example of TDM 6ch.
253Driver can automatically switches TDM <-> stereo mode in this case.
254
255see "Example: simple sound card for TDM"