167 lines
4.4 KiB
ReStructuredText
167 lines
4.4 KiB
ReStructuredText
============================
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ALSA Jack Software Injection
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============================
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Simple Introduction On Jack Injection
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=====================================
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Here jack injection means users could inject plugin or plugout events
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to the audio jacks through debugfs interface, it is helpful to
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validate ALSA userspace changes. For example, we change the audio
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profile switching code in the pulseaudio, and we want to verify if the
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change works as expected and if the change introduce the regression,
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in this case, we could inject plugin or plugout events to an audio
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jack or to some audio jacks, we don't need to physically access the
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machine and plug/unplug physical devices to the audio jack.
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In this design, an audio jack doesn't equal to a physical audio jack.
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Sometimes a physical audio jack contains multi functions, and the
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ALSA driver creates multi ``jack_kctl`` for a ``snd_jack``, here the
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``snd_jack`` represents a physical audio jack and the ``jack_kctl``
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represents a function, for example a physical jack has two functions:
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headphone and mic_in, the ALSA ASoC driver will build 2 ``jack_kctl``
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for this jack. The jack injection is implemented based on the
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``jack_kctl`` instead of ``snd_jack``.
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To inject events to audio jacks, we need to enable the jack injection
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via ``sw_inject_enable`` first, once it is enabled, this jack will not
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change the state by hardware events anymore, we could inject plugin or
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plugout events via ``jackin_inject`` and check the jack state via
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``status``, after we finish our test, we need to disable the jack
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injection via ``sw_inject_enable`` too, once it is disabled, the jack
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state will be restored according to the last reported hardware events
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and will change by future hardware events.
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The Layout of Jack Injection Interface
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======================================
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If users enable the SND_JACK_INJECTION_DEBUG in the kernel, the audio
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jack injection interface will be created as below:
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::
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$debugfs_mount_dir/sound
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|-- card0
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|-- |-- HDMI_DP_pcm_10_Jack
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|-- |-- |-- jackin_inject
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|-- |-- |-- kctl_id
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|-- |-- |-- mask_bits
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|-- |-- |-- status
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|-- |-- |-- sw_inject_enable
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|-- |-- |-- type
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...
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|-- |-- HDMI_DP_pcm_9_Jack
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|-- |-- jackin_inject
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|-- |-- kctl_id
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|-- |-- mask_bits
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|-- |-- status
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|-- |-- sw_inject_enable
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|-- |-- type
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|-- card1
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|-- HDMI_DP_pcm_5_Jack
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|-- |-- jackin_inject
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|-- |-- kctl_id
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|-- |-- mask_bits
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|-- |-- status
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|-- |-- sw_inject_enable
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|-- |-- type
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...
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|-- Headphone_Jack
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|-- |-- jackin_inject
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|-- |-- kctl_id
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|-- |-- mask_bits
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|-- |-- status
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|-- |-- sw_inject_enable
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|-- |-- type
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|-- Headset_Mic_Jack
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|-- jackin_inject
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|-- kctl_id
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|-- mask_bits
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|-- status
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|-- sw_inject_enable
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|-- type
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The Explanation Of The Nodes
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======================================
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kctl_id
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read-only, get jack_kctl->kctl's id
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::
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sound/card1/Headphone_Jack# cat kctl_id
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Headphone Jack
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mask_bits
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read-only, get jack_kctl's supported events mask_bits
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::
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sound/card1/Headphone_Jack# cat mask_bits
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0x0001 HEADPHONE(0x0001)
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status
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read-only, get jack_kctl's current status
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- headphone unplugged:
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::
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sound/card1/Headphone_Jack# cat status
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Unplugged
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- headphone plugged:
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::
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sound/card1/Headphone_Jack# cat status
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Plugged
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type
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read-only, get snd_jack's supported events from type (all supported events on the physical audio jack)
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::
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sound/card1/Headphone_Jack# cat type
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0x7803 HEADPHONE(0x0001) MICROPHONE(0x0002) BTN_3(0x0800) BTN_2(0x1000) BTN_1(0x2000) BTN_0(0x4000)
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sw_inject_enable
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read-write, enable or disable injection
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- injection disabled:
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::
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sound/card1/Headphone_Jack# cat sw_inject_enable
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Jack: Headphone Jack Inject Enabled: 0
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- injection enabled:
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::
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sound/card1/Headphone_Jack# cat sw_inject_enable
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Jack: Headphone Jack Inject Enabled: 1
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- to enable jack injection:
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::
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sound/card1/Headphone_Jack# echo 1 > sw_inject_enable
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- to disable jack injection:
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::
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sound/card1/Headphone_Jack# echo 0 > sw_inject_enable
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jackin_inject
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write-only, inject plugin or plugout
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- to inject plugin:
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::
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sound/card1/Headphone_Jack# echo 1 > jackin_inject
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- to inject plugout:
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::
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sound/card1/Headphone_Jack# echo 0 > jackin_inject
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