From: Takashi Iwai <tiwai@suse.de>
To: alsa-devel@alsa-project.org
Subject: [PATCH 4/4] ALSA: usb-audio: Update the documentation for the new delayed_register option
Date: Wed, 25 Mar 2020 11:33:22 +0100 [thread overview]
Message-ID: <20200325103322.2508-5-tiwai@suse.de> (raw)
In-Reply-To: <20200325103322.2508-1-tiwai@suse.de>
Just adding a brief explanation to alsa-configuration.rst.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
Documentation/sound/alsa-configuration.rst | 13 +++++++++++++
1 file changed, 13 insertions(+)
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.
--
2.16.4
prev parent reply other threads:[~2020-03-25 10:37 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-25 10:33 [PATCH 0/4] ALSA: usb-audio: Option for delayed registration Takashi Iwai
2020-03-25 10:33 ` [PATCH 1/4] ALSA: usb-audio: Rewrite registration quirk handling Takashi Iwai
2020-03-25 10:33 ` [PATCH 2/4] ALSA: usb-audio: Add delayed_register option Takashi Iwai
2020-03-25 10:33 ` [PATCH 3/4] ALSA: usb-audio: Inform devices that need delayed registration Takashi Iwai
2020-03-25 10:33 ` Takashi Iwai [this message]
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