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There are several features of the Line6 USB driver which require PCM data to be exchanged with the device: *) PCM playback and capture via ALSA *) software monitoring (for devices without hardware monitoring) *) optional impulse response measurement However, from the device's point of view, there is just a single capture and playback stream, which must be shared between these subsystems. It is therefore necessary to maintain the state of the subsystems with respect to PCM usage. We define several constants of the form LINE6_BIT_PCM_<subsystem>_<direction>_<resource> with the following meanings: *) <subsystem> is one of -) ALSA: PCM playback and capture via ALSA -) MONITOR: software monitoring -) IMPULSE: optional impulse response measurement *) <direction> is one of -) PLAYBACK: audio output (from host to device) -) CAPTURE: audio input (from device to host) *) <resource> is one of -) BUFFER: buffer required by PCM data stream -) STREAM: actual PCM data stream The subsystems call line6_pcm_acquire() to acquire the (shared) resources needed for a particular operation (e.g., allocate the buffer for ALSA playback or start the capture stream for software monitoring). When a resource is no longer needed, it is released by calling line6_pcm_release(). Buffer allocation and stream startup are handled separately to allow the ALSA kernel driver to perform them at appropriate places (since the callback which starts a PCM stream is not allowed to sleep). Signed-off-by: Markus Grabner <grabner@icg.tugraz.at> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
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| .. | ||
| audio.c | ||
| audio.h | ||
| capture.c | ||
| capture.h | ||
| config.h | ||
| control.c | ||
| control.h | ||
| driver.c | ||
| driver.h | ||
| dumprequest.c | ||
| dumprequest.h | ||
| Kconfig | ||
| Makefile | ||
| midi.c | ||
| midi.h | ||
| midibuf.c | ||
| midibuf.h | ||
| pcm.c | ||
| pcm.h | ||
| playback.c | ||
| playback.h | ||
| pod.c | ||
| pod.h | ||
| podhd.c | ||
| podhd.h | ||
| revision.h | ||
| toneport.c | ||
| toneport.h | ||
| usbdefs.h | ||
| variax.c | ||
| variax.h | ||