Support for generic sound devices.
If you don't have a sound card in your computer, you can include a driver for the PC speaker which allows it to act like a primitive sound card. This driver also replaces the pcspkr driver for beeps. You can compile this as a module which will be called snd-pcsp. WARNING: if you already have a soundcard, enabling this driver may lead to a problem. Namely, it may get loaded before the other sound driver of yours, making the pc-speaker a default sound device. Which is likely not what you want. To make this driver play nicely with other sound driver, you can add this into your /etc/modprobe.conf: options snd-pcsp index=2 You don't need this driver if you only want your pc-speaker to beep. You don't need this driver if you have a tablet piezo beeper in your PC instead of the real speaker. Say N if you have a sound card. Say M if you don't. Say Y only if you really know what you do.
Say Y here to include the dummy driver. This driver does nothing, but emulates various mixer controls and PCM devices. You don't need this unless you're testing the hardware support of programs using the ALSA API. To compile this driver as a module, choose M here: the module will be called snd-dummy.
Say 'Y' or 'M' to include support for the PCM loopback device. This module returns played samples back to the user space using the standard ALSA PCM device. The devices are routed 0->1 and 1->0, where first number is the playback PCM device and second number is the capture device. Module creates two PCM devices and configured number of substreams (see the pcm_substreams module parameter). The looback device allow time sychronization with an external timing source using the time shift universal control (+-20% of system time). To compile this driver as a module, choose M here: the module will be called snd-aloop.
Say Y here to include the virtual MIDI driver. This driver allows to connect applications using raw MIDI devices to sequencer clients. If you don't know what MIDI is, say N here. To compile this driver as a module, choose M here: the module will be called snd-virmidi.
To use a MOTU MidiTimePiece AV multiport MIDI adapter connected to the parallel port, say Y here and make sure that the standard parallel port driver isn't used for the port. To compile this driver as a module, choose M here: the module will be called snd-mtpav.
The ESI Miditerminal 4140 is a 4 In 4 Out MIDI Interface with additional SMPTE Timecode capabilities for the parallel port. Say 'Y' to include support for this device. To compile this driver as a module, chose 'M' here: the module will be called snd-mts64.
To include support for MIDI serial port interfaces, say Y here and read <file:Documentation/sound/alsa/serial-u16550.txt>. This driver works with serial UARTs 16550 and better. This driver accesses the serial port hardware directly, so make sure that the standard serial driver isn't used or deactivated with setserial before loading this driver. To compile this driver as a module, choose M here: the module will be called snd-serial-u16550.
Say Y here to include support for MIDI ports compatible with the Roland MPU-401 interface in UART mode. To compile this driver as a module, choose M here: the module will be called snd-mpu401.
Say Y here to include support for Midiman Portman 2x4 parallel port MIDI device. To compile this driver as a module, choose M here: the module will be called snd-portman2x4.
Say Y here to include support for the opb_ac97_controller_ref_v1_00_a ip core found in Xilinx's ML403 reference design. To compile this driver as a module, choose M here: the module will be called snd-ml403_ac97cr.
Say Y here to enable the aggressive power-saving support of AC97 codecs. In this mode, the power-mode is dynamically controlled at each open/close. The mode is activated by passing 'power_save=X' to the snd-ac97-codec driver module, where 'X' is the time-out value, a nonnegative integer that specifies how many seconds of idle time the driver must count before it may put the AC97 into power-save mode; a value of 0 (zero) disables the use of this power-save mode. After the snd-ac97-codec driver module has been loaded, the 'power_save' parameter can be set via sysfs as follows: echo 10 > /sys/module/snd_ac97_codec/parameters/power_save In this case, the time-out is set to 10 seconds; setting the time-out to 1 second (the minimum activation value) isn't recommended because many applications try to reopen the device frequently. A value of 10 seconds would be a good choice for normal operations. See Documentation/sound/alsa/powersave.txt for more details.
The default time-out value in seconds for AC97 automatic power-save mode. 0 means to disable the power-save mode. See SND_AC97_POWER_SAVE for more details.