name : 78-sound-card.rules # do not edit this file, it will be overwritten on update SUBSYSTEM!="sound", GOTO="sound_end" ACTION=="add|change", KERNEL=="controlC*", ATTR{../uevent}="change" ACTION!="change", GOTO="sound_end" # Ok, we probably need a little explanation here for what the two lines above # are good for. # # The story goes like this: when ALSA registers a new sound card it emits a # series of 'add' events to userspace, for the main card device and for all the # child device nodes that belong to it. udev relays those to applications, # however only maintains the order between father and child, but not between # the siblings. The control device node creation can be used as synchronization # point. All other devices that belong to a card are created in the kernel # before it. However unfortunately due to the fact that siblings are forwarded # out of order by udev this fact is lost to applications. # # OTOH before an application can open a device it needs to make sure that all # its device nodes are completely created and set up. # # As a workaround for this issue we have added the udev rule above which will # generate a 'change' event on the main card device from the 'add' event of the # card's control device. Due to the ordering semantics of udev this event will # only be relayed after all child devices have finished processing properly. # When an application needs to listen for appearing devices it can hence look # for 'change' events only, and ignore the actual 'add' events. # # When the application is initialized at the same time as a device is plugged # in it may need to figure out if the 'change' event has already been triggered # or not for a card. To find that out we store the flag environment variable # SOUND_INITIALIZED on the device which simply tells us if the card 'change' # event has already been processed. KERNEL!="card*", GOTO="sound_end" ENV{SOUND_INITIALIZED}="1" IMPORT{builtin}="hwdb" SUBSYSTEMS=="usb", IMPORT{builtin}="usb_id" SUBSYSTEMS=="usb", GOTO="skip_pci" SUBSYSTEMS=="firewire", ATTRS{guid}=="?*", \ ENV{ID_BUS}="firewire", ENV{ID_SERIAL}="$attr{guid}", ENV{ID_SERIAL_SHORT}="$attr{guid}", \ ENV{ID_VENDOR_ID}="$attr{vendor}", ENV{ID_MODEL_ID}="$attr{model}", \ ENV{ID_VENDOR}="$attr{vendor_name}", ENV{ID_MODEL}="$attr{model_name}" SUBSYSTEMS=="firewire", GOTO="skip_pci" SUBSYSTEMS=="pci", ENV{ID_BUS}="pci", ENV{ID_VENDOR_ID}="$attr{vendor}", ENV{ID_MODEL_ID}="$attr{device}" SUBSYSTEMS=="pci", GOTO="skip_pci" # If we reach here, the device nor any of its parents are USB/PCI/firewire bus devices. # If we now find a parent that is a platform device, assume that we're working with # an internal sound card. SUBSYSTEMS=="platform", ENV{SOUND_FORM_FACTOR}="internal", GOTO="sound_end" LABEL="skip_pci" # Define ID_ID if ID_BUS and ID_SERIAL are set. This will work for both # USB and firewire. ENV{ID_SERIAL}=="?*", ENV{ID_USB_INTERFACE_NUM}=="?*", ENV{ID_ID}="$env{ID_BUS}-$env{ID_SERIAL}-$env{ID_USB_INTERFACE_NUM}" ENV{ID_SERIAL}=="?*", ENV{ID_USB_INTERFACE_NUM}=="", ENV{ID_ID}="$env{ID_BUS}-$env{ID_SERIAL}" IMPORT{builtin}="path_id" # The values used here for $SOUND_FORM_FACTOR and $SOUND_CLASS should be kept # in sync with those defined for PulseAudio's src/pulse/proplist.h # PA_PROP_DEVICE_FORM_FACTOR, PA_PROP_DEVICE_CLASS properties. # If the first PCM device of this card has the pcm class 'modem', then the card is a modem ATTR{pcmC%nD0p/pcm_class}=="modem", ENV{SOUND_CLASS}="modem", GOTO="sound_end" # Identify cards on the internal PCI bus as internal SUBSYSTEMS=="pci", DEVPATH=="*/0000:00:??.?/sound/*", ENV{SOUND_FORM_FACTOR}="internal", GOTO="sound_end" # Devices that also support Image/Video interfaces are most likely webcams SUBSYSTEMS=="usb", ENV{ID_USB_INTERFACES}=="*:0e????:*", ENV{SOUND_FORM_FACTOR}="webcam", GOTO="sound_end" # Matching on the model strings is a bit ugly, I admit ENV{ID_MODEL}=="*[Ss]peaker*", ENV{SOUND_FORM_FACTOR}="speaker", GOTO="sound_end" ENV{ID_MODEL_FROM_DATABASE}=="*[Ss]peaker*", ENV{SOUND_FORM_FACTOR}="speaker", GOTO="sound_end" ENV{ID_MODEL}=="*[Hh]eadphone*", ENV{SOUND_FORM_FACTOR}="headphone", GOTO="sound_end" ENV{ID_MODEL_FROM_DATABASE}=="*[Hh]eadphone*", ENV{SOUND_FORM_FACTOR}="headphone", GOTO="sound_end" ENV{ID_MODEL}=="*[Hh]eadset*", ENV{SOUND_FORM_FACTOR}="headset", GOTO="sound_end" ENV{ID_MODEL_FROM_DATABASE}=="*[Hh]eadset*", ENV{SOUND_FORM_FACTOR}="headset", GOTO="sound_end" ENV{ID_MODEL}=="*[Hh]andset*", ENV{SOUND_FORM_FACTOR}="handset", GOTO="sound_end" ENV{ID_MODEL_FROM_DATABASE}=="*[Hh]andset*", ENV{SOUND_FORM_FACTOR}="handset", GOTO="sound_end" ENV{ID_MODEL}=="*[Mm]icrophone*", ENV{SOUND_FORM_FACTOR}="microphone", GOTO="sound_end" ENV{ID_MODEL_FROM_DATABASE}=="*[Mm]icrophone*", ENV{SOUND_FORM_FACTOR}="microphone", GOTO="sound_end" LABEL="sound_end"