Difference between revisions of "Research Pre Audio"

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(update about audio scripts)
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A good start to dive into this is sound/arm/omap-twl4030/script.c in the kernel patch from palm.
 
A good start to dive into this is sound/arm/omap-twl4030/script.c in the kernel patch from palm.
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 +
New scripts are inserted into the kernel list via:
 +
 +
<pre>
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/sys/devices/platform/twl4030_audio/scinit
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</pre>
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This is also handled by audiod. Until now there was no place found where the scripts may be stored in the filesystem. Maybe they are build into audiod.

Revision as of 17:48, 21 October 2009

This side should cover the audio architecture used on the Palm Pre.

Hardware

The used TWL4030 PMIC covers the audio part.

Soundcards

root@castle:/var/home/root# aplay -l    
**** List of PLAYBACK Hardware Devices ****
card 0: mcbsp2 [twl4030-i2s (mcbsp2)], device 0: omap-mcbsp-pcm [omap-mcbsp-pcm]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: mcbsp3 [btsco (mcbsp3)], device 0: omap-mcbsp-pcm [omap-mcbsp-pcm]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

Scripts

Palm uses scripts to configure the lower levels of the sound system that are executed inside the kernel. Audiod triggers them over a sysfs interface.

echo "#list" > /sys/devices/platform/twl4030_audio/scdebug
for example lists you all available scripts over the kernel message output which you can view with dmesg. You can also try
#all
#volume
#init

These scripts can be triggered by writing is name as a string into

/sys/devices/platform/twl4030_audio/scrun

A good start to dive into this is sound/arm/omap-twl4030/script.c in the kernel patch from palm.

New scripts are inserted into the kernel list via:

/sys/devices/platform/twl4030_audio/scinit

This is also handled by audiod. Until now there was no place found where the scripts may be stored in the filesystem. Maybe they are build into audiod.