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| author | Takashi Iwai <tiwai@suse.de> | 2020-03-25 11:33:22 +0100 |
|---|---|---|
| committer | Takashi Iwai <tiwai@suse.de> | 2020-03-26 10:49:21 +0100 |
| commit | 2ceb65cd04a9b7d694188b72807f2e1fead16d9c (patch) | |
| tree | a172a7b315b284374879919d4e733554cf182d0e /Documentation | |
| parent | a4aad5636c7298eecfb60fc9d73933336cb0c4d8 (diff) | |
ALSA: usb-audio: Update the documentation for the new delayed_register option
Just adding a brief explanation to alsa-configuration.rst.
Link: https://lore.kernel.org/r/20200325103322.2508-5-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/sound/alsa-configuration.rst | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/Documentation/sound/alsa-configuration.rst b/Documentation/sound/alsa-configuration.rst index 392875a1b94e..72f97d4b01a7 100644 --- a/Documentation/sound/alsa-configuration.rst +++ b/Documentation/sound/alsa-configuration.rst @@ -2234,6 +2234,19 @@ use_vmalloc buffers. If mmap is used on such architectures, turn off this option, so that the DMA-coherent buffers are allocated and used instead. +delayed_register + The option is needed for devices that have multiple streams + defined in multiple USB interfaces. The driver may invoke + registrations multiple times (once per interface) and this may + lead to the insufficient device enumeration. + This option receives an array of strings, and you can pass + ID:INTERFACE like ``0123abcd:4`` for performing the delayed + registration to the given device. In this example, when a USB + device 0123:abcd is probed, the driver waits the registration + until the USB interface 4 gets probed. + The driver prints a message like "Found post-registration device + assignment: 1234abcd:04" for such a device, so that user can + notice the need. This module supports multiple devices, autoprobe and hotplugging. |