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a0e0d13542
This patch implements a PCM interface for streaming hotword phrases over SPI. Userspace can open the PCM device at anytime. The stream is blocked when no hotword is detected. The mic audio buffer on the DSP is a ~128KByte ring buffer that holds ~4sec of audio samples recorded from the DMIC (S16_LE, mono, 16KHz). After a hotword is detected, previous 2 seconds of audio (containing the detected hotword) is streamed first, then live capture continues until userspace closes the PCM stream. When transferring, copy one period at a time then call snd_pcm_period_elapsed(). This reduces the latency of transferring the initial ~2sec of audio after hotword detect since audio samples are available for userspace earlier. Signed-off-by: Ben Zhang <benzh@chromium.org> Signed-off-by: Curtis Malainey <cujomalainey@chromium.org> Link: https://lore.kernel.org/r/20191018200449.141123-2-cujomalainey@chromium.org Signed-off-by: Mark Brown <broonie@kernel.org> |
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| .. | ||
| ac97 | ||
| aoa | ||
| arm | ||
| atmel | ||
| core | ||
| drivers | ||
| firewire | ||
| hda | ||
| i2c | ||
| isa | ||
| mips | ||
| oss | ||
| parisc | ||
| pci | ||
| pcmcia | ||
| ppc | ||
| sh | ||
| soc | ||
| sparc | ||
| spi | ||
| synth | ||
| usb | ||
| x86 | ||
| xen | ||
| ac97_bus.c | ||
| Kconfig | ||
| last.c | ||
| Makefile | ||
| sound_core.c | ||