DSP_CAP_DUPLEX 1985 sound/core/oss/pcm_oss.c res &= ~DSP_CAP_DUPLEX; DSP_CAP_DUPLEX 2009 sound/core/oss/pcm_oss.c result = DSP_CAP_TRIGGER | DSP_CAP_MMAP | DSP_CAP_DUPLEX | DSP_CAP_REALTIME; DSP_CAP_DUPLEX 2696 sound/core/oss/pcm_oss.c if (snd_pcm_oss_get_caps(pcm_oss_file) & DSP_CAP_DUPLEX)