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/sh/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" 256