diff options
Diffstat (limited to 'Documentation/sound/soc/dpcm.rst')
| -rw-r--r-- | Documentation/sound/soc/dpcm.rst | 45 |
1 files changed, 21 insertions, 24 deletions
diff --git a/Documentation/sound/soc/dpcm.rst b/Documentation/sound/soc/dpcm.rst index f6845b2278ea..7b6aeab3c207 100644 --- a/Documentation/sound/soc/dpcm.rst +++ b/Documentation/sound/soc/dpcm.rst @@ -13,7 +13,7 @@ drivers that expose several ALSA PCMs and can route to multiple DAIs. The DPCM runtime routing is determined by the ALSA mixer settings in the same way as the analog signal is routed in an ASoC codec driver. DPCM uses a DAPM graph representing the DSP internal audio paths and uses the mixer settings to -determine the patch used by each ALSA PCM. +determine the path used by each ALSA PCM. DPCM re-uses all the existing component codec, platform and DAI drivers without any modifications. @@ -101,7 +101,7 @@ The audio driver processes this as follows :- 4. Machine driver or audio HAL enables the speaker path. -5. DPCM runs the PCM ops for startup(), hw_params(), prepapre() and +5. DPCM runs the PCM ops for startup(), hw_params(), prepare() and trigger(start) for DAI1 Speakers since the path is enabled. In this example, the machine driver or userspace audio HAL can alter the routing @@ -147,25 +147,25 @@ For the example above we have to define 4 FE DAI links and 6 BE DAI links. The FE DAI links are defined as follows :- :: + SND_SOC_DAILINK_DEFS(pcm0, + DAILINK_COMP_ARRAY(COMP_CPU("System Pin")), + DAILINK_COMP_ARRAY(COMP_DUMMY()), + DAILINK_COMP_ARRAY(COMP_PLATFORM("dsp-audio"))); + static struct snd_soc_dai_link machine_dais[] = { { .name = "PCM0 System", .stream_name = "System Playback", - .cpu_dai_name = "System Pin", - .platform_name = "dsp-audio", - .codec_name = "snd-soc-dummy", - .codec_dai_name = "snd-soc-dummy-dai", + SND_SOC_DAILINK_REG(pcm0), .dynamic = 1, .trigger = {SND_SOC_DPCM_TRIGGER_POST, SND_SOC_DPCM_TRIGGER_POST}, - .dpcm_playback = 1, }, .....< other FE and BE DAI links here > }; This FE DAI link is pretty similar to a regular DAI link except that we also -set the DAI link to a DPCM FE with the ``dynamic = 1``. The supported FE stream -directions should also be set with the ``dpcm_playback`` and ``dpcm_capture`` -flags. There is also an option to specify the ordering of the trigger call for +set the DAI link to a DPCM FE with the ``dynamic = 1``. +There is also an option to specify the ordering of the trigger call for each FE. This allows the ASoC core to trigger the DSP before or after the other components (as some DSPs have strong requirements for the ordering DAI/DSP start and stop sequences). @@ -176,28 +176,26 @@ dynamic and will change depending on runtime config. The BE DAIs are configured as follows :- :: + SND_SOC_DAILINK_DEFS(headset, + DAILINK_COMP_ARRAY(COMP_CPU("ssp-dai.0")), + DAILINK_COMP_ARRAY(COMP_CODEC("rt5640.0-001c", "rt5640-aif1"))); + static struct snd_soc_dai_link machine_dais[] = { .....< FE DAI links here > { .name = "Codec Headset", - .cpu_dai_name = "ssp-dai.0", - .platform_name = "snd-soc-dummy", + SND_SOC_DAILINK_REG(headset), .no_pcm = 1, - .codec_name = "rt5640.0-001c", - .codec_dai_name = "rt5640-aif1", .ignore_suspend = 1, .ignore_pmdown_time = 1, .be_hw_params_fixup = hswult_ssp0_fixup, .ops = &haswell_ops, - .dpcm_playback = 1, - .dpcm_capture = 1, }, .....< other BE DAI links here > }; This BE DAI link connects DAI0 to the codec (in this case RT5460 AIF1). It sets -the ``no_pcm`` flag to mark it has a BE and sets flags for supported stream -directions using ``dpcm_playback`` and ``dpcm_capture`` above. +the ``no_pcm`` flag to mark it has a BE. The BE has also flags set for ignoring suspend and PM down time. This allows the BE to work in a hostless mode where the host CPU is not transferring data @@ -221,7 +219,7 @@ like a BT phone call :- This allows the host CPU to sleep while the DSP, MODEM DAI and the BT DAI are still in operation. -A BE DAI link can also set the codec to a dummy device if the code is a device +A BE DAI link can also set the codec to a dummy device if the codec is a device that is managed externally. Likewise a BE DAI can also set a dummy cpu DAI if the CPU DAI is managed by the @@ -249,7 +247,7 @@ configuration. struct snd_interval *channels = hw_param_interval(params, SNDRV_PCM_HW_PARAM_CHANNELS); - /* The DSP will covert the FE rate to 48k, stereo */ + /* The DSP will convert the FE rate to 48k, stereo */ rate->min = rate->max = 48000; channels->min = channels->max = 2; @@ -367,8 +365,9 @@ The machine driver sets some additional parameters to the DAI link i.e. .codec_dai_name = "modem-aif1", .codec_name = "modem", .dai_fmt = SND_SOC_DAIFMT_I2S | SND_SOC_DAIFMT_NB_NF - | SND_SOC_DAIFMT_CBM_CFM, - .params = &dai_params, + | SND_SOC_DAIFMT_CBP_CFP, + .c2c_params = &dai_params, + .num_c2c_params = 1, } < ... more DAI links here ... > @@ -386,5 +385,3 @@ This means creating a new FE that is connected with a virtual path to both DAI links. The DAI links will be started when the FE PCM is started and stopped when the FE PCM is stopped. Note that the FE PCM cannot read or write data in this configuration. - - |