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author | Takashi Iwai <tiwai@suse.de> | 2016-11-11 00:26:58 +0300 |
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committer | Takashi Iwai <tiwai@suse.de> | 2016-11-11 19:34:14 +0300 |
commit | 8155258a7d7600e7b92c6193cf23a11e281a9b0b (patch) | |
tree | e0a447488d0c48f27d3fe65d1da228640d2de53d /Documentation/sound/alsa/soc | |
parent | fb3df950833c1e8c39a82313942e6375f3f498c6 (diff) | |
download | linux-8155258a7d7600e7b92c6193cf23a11e281a9b0b.tar.xz |
ASoC: doc: ReSTize jack.txt
A simple conversion from a plain text file.
Acked-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'Documentation/sound/alsa/soc')
-rw-r--r-- | Documentation/sound/alsa/soc/jack.txt | 71 |
1 files changed, 0 insertions, 71 deletions
diff --git a/Documentation/sound/alsa/soc/jack.txt b/Documentation/sound/alsa/soc/jack.txt deleted file mode 100644 index fcf82a417293..000000000000 --- a/Documentation/sound/alsa/soc/jack.txt +++ /dev/null @@ -1,71 +0,0 @@ -ASoC jack detection -=================== - -ALSA has a standard API for representing physical jacks to user space, -the kernel side of which can be seen in include/sound/jack.h. ASoC -provides a version of this API adding two additional features: - - - It allows more than one jack detection method to work together on one - user visible jack. In embedded systems it is common for multiple - to be present on a single jack but handled by separate bits of - hardware. - - - Integration with DAPM, allowing DAPM endpoints to be updated - automatically based on the detected jack status (eg, turning off the - headphone outputs if no headphones are present). - -This is done by splitting the jacks up into three things working -together: the jack itself represented by a struct snd_soc_jack, sets of -snd_soc_jack_pins representing DAPM endpoints to update and blocks of -code providing jack reporting mechanisms. - -For example, a system may have a stereo headset jack with two reporting -mechanisms, one for the headphone and one for the microphone. Some -systems won't be able to use their speaker output while a headphone is -connected and so will want to make sure to update both speaker and -headphone when the headphone jack status changes. - -The jack - struct snd_soc_jack -============================== - -This represents a physical jack on the system and is what is visible to -user space. The jack itself is completely passive, it is set up by the -machine driver and updated by jack detection methods. - -Jacks are created by the machine driver calling snd_soc_jack_new(). - -snd_soc_jack_pin -================ - -These represent a DAPM pin to update depending on some of the status -bits supported by the jack. Each snd_soc_jack has zero or more of these -which are updated automatically. They are created by the machine driver -and associated with the jack using snd_soc_jack_add_pins(). The status -of the endpoint may configured to be the opposite of the jack status if -required (eg, enabling a built in microphone if a microphone is not -connected via a jack). - -Jack detection methods -====================== - -Actual jack detection is done by code which is able to monitor some -input to the system and update a jack by calling snd_soc_jack_report(), -specifying a subset of bits to update. The jack detection code should -be set up by the machine driver, taking configuration for the jack to -update and the set of things to report when the jack is connected. - -Often this is done based on the status of a GPIO - a handler for this is -provided by the snd_soc_jack_add_gpio() function. Other methods are -also available, for example integrated into CODECs. One example of -CODEC integrated jack detection can be see in the WM8350 driver. - -Each jack may have multiple reporting mechanisms, though it will need at -least one to be useful. - -Machine drivers -=============== - -These are all hooked together by the machine driver depending on the -system hardware. The machine driver will set up the snd_soc_jack and -the list of pins to update then set up one or more jack detection -mechanisms to update that jack based on their current status. |