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We have a system which has the HDMI audio capability internally, but pulseaudio is not giving it a very high priority compared to e.g. USB sound cards. The sound device appears on the platform bus and it is not currently tagged with any form factor information. It seems safe to assume that any sound card that is directly on the platform bus is of internal form factor, but we must be careful because udev rules will match all parent devices, not just the immediate parent, and you will frequently encounter setups such as: Platform bus -> USB host controller -> USB sound card In that case, SUBSYSTEMS==platform would match even though we're clearly working with an external USB sound card. In order to detect true platform devices here, we rely on the observation that if any parent devices of the sound card are PCI, USB or firewire devices, then this sound card cannot directly connected to the platform bus. Otherwise, if we find a parent device on the platform bus, we assume this is an internal sound card connected directly to the platform bus.
97 lines
4.7 KiB
Plaintext
97 lines
4.7 KiB
Plaintext
# do not edit this file, it will be overwritten on update
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SUBSYSTEM!="sound", GOTO="sound_end"
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ACTION=="add|change", KERNEL=="controlC*", ATTR{../uevent}="change"
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ACTION!="change", GOTO="sound_end"
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# Ok, we probably need a little explanation here for what the two lines above
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# are good for.
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#
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# The story goes like this: when ALSA registers a new sound card it emits a
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# series of 'add' events to userspace, for the main card device and for all the
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# child device nodes that belong to it. udev relays those to applications,
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# however only maintains the order between father and child, but not between
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# the siblings. The control device node creation can be used as synchronization
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# point. All other devices that belong to a card are created in the kernel
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# before it. However unfortunately due to the fact that siblings are forwarded
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# out of order by udev this fact is lost to applications.
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#
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# OTOH before an application can open a device it needs to make sure that all
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# its device nodes are completely created and set up.
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#
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# As a workaround for this issue we have added the udev rule above which will
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# generate a 'change' event on the main card device from the 'add' event of the
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# card's control device. Due to the ordering semantics of udev this event will
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# only be relayed after all child devices have finished processing properly.
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# When an application needs to listen for appearing devices it can hence look
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# for 'change' events only, and ignore the actual 'add' events.
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#
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# When the application is initialized at the same time as a device is plugged
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# in it may need to figure out if the 'change' event has already been triggered
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# or not for a card. To find that out we store the flag environment variable
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# SOUND_INITIALIZED on the device which simply tells us if the card 'change'
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# event has already been processed.
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KERNEL!="card*", GOTO="sound_end"
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ENV{SOUND_INITIALIZED}="1"
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IMPORT{builtin}="hwdb"
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SUBSYSTEMS=="usb", IMPORT{builtin}="usb_id"
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SUBSYSTEMS=="usb", GOTO="skip_pci"
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SUBSYSTEMS=="firewire", ATTRS{guid}=="?*", \
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ENV{ID_BUS}="firewire", ENV{ID_SERIAL}="$attr{guid}", ENV{ID_SERIAL_SHORT}="$attr{guid}", \
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ENV{ID_VENDOR_ID}="$attr{vendor}", ENV{ID_MODEL_ID}="$attr{model}", \
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ENV{ID_VENDOR}="$attr{vendor_name}", ENV{ID_MODEL}="$attr{model_name}"
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SUBSYSTEMS=="firewire", GOTO="skip_pci"
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SUBSYSTEMS=="pci", ENV{ID_BUS}="pci", ENV{ID_VENDOR_ID}="$attr{vendor}", ENV{ID_MODEL_ID}="$attr{device}"
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SUBSYSTEMS=="pci", GOTO="skip_pci"
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# If we reach here, the device nor any of its parents are USB/PCI/firewire bus devices.
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# If we now find a parent that is a platform device, assume that we're working with
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# an internal sound card.
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SUBSYSTEMS=="platform", ENV{SOUND_FORM_FACTOR}="internal", GOTO="sound_end"
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LABEL="skip_pci"
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# Define ID_ID if ID_BUS and ID_SERIAL are set. This will work for both
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# USB and firewire.
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ENV{ID_SERIAL}=="?*", ENV{ID_USB_INTERFACE_NUM}=="?*", ENV{ID_ID}="$env{ID_BUS}-$env{ID_SERIAL}-$env{ID_USB_INTERFACE_NUM}"
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ENV{ID_SERIAL}=="?*", ENV{ID_USB_INTERFACE_NUM}=="", ENV{ID_ID}="$env{ID_BUS}-$env{ID_SERIAL}"
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IMPORT{builtin}="path_id"
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# The values used here for $SOUND_FORM_FACTOR and $SOUND_CLASS should be kept
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# in sync with those defined for PulseAudio's src/pulse/proplist.h
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# PA_PROP_DEVICE_FORM_FACTOR, PA_PROP_DEVICE_CLASS properties.
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# If the first PCM device of this card has the pcm class 'modem', then the card is a modem
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ATTR{pcmC%nD0p/pcm_class}=="modem", ENV{SOUND_CLASS}="modem", GOTO="sound_end"
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# Identify cards on the internal PCI bus as internal
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SUBSYSTEMS=="pci", DEVPATH=="*/0000:00:??.?/sound/*", ENV{SOUND_FORM_FACTOR}="internal", GOTO="sound_end"
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# Devices that also support Image/Video interfaces are most likely webcams
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SUBSYSTEMS=="usb", ENV{ID_USB_INTERFACES}=="*:0e????:*", ENV{SOUND_FORM_FACTOR}="webcam", GOTO="sound_end"
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# Matching on the model strings is a bit ugly, I admit
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ENV{ID_MODEL}=="*[Ss]peaker*", ENV{SOUND_FORM_FACTOR}="speaker", GOTO="sound_end"
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ENV{ID_MODEL_FROM_DATABASE}=="*[Ss]peaker*", ENV{SOUND_FORM_FACTOR}="speaker", GOTO="sound_end"
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ENV{ID_MODEL}=="*[Hh]eadphone*", ENV{SOUND_FORM_FACTOR}="headphone", GOTO="sound_end"
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ENV{ID_MODEL_FROM_DATABASE}=="*[Hh]eadphone*", ENV{SOUND_FORM_FACTOR}="headphone", GOTO="sound_end"
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ENV{ID_MODEL}=="*[Hh]eadset*", ENV{SOUND_FORM_FACTOR}="headset", GOTO="sound_end"
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ENV{ID_MODEL_FROM_DATABASE}=="*[Hh]eadset*", ENV{SOUND_FORM_FACTOR}="headset", GOTO="sound_end"
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ENV{ID_MODEL}=="*[Hh]andset*", ENV{SOUND_FORM_FACTOR}="handset", GOTO="sound_end"
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ENV{ID_MODEL_FROM_DATABASE}=="*[Hh]andset*", ENV{SOUND_FORM_FACTOR}="handset", GOTO="sound_end"
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ENV{ID_MODEL}=="*[Mm]icrophone*", ENV{SOUND_FORM_FACTOR}="microphone", GOTO="sound_end"
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ENV{ID_MODEL_FROM_DATABASE}=="*[Mm]icrophone*", ENV{SOUND_FORM_FACTOR}="microphone", GOTO="sound_end"
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LABEL="sound_end"
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