Jaroslav Kysela [Thu, 27 Jan 2022 12:15:46 +0000 (13:15 +0100)]
speaker-test: remove sample_map.csv
The CSV file is not used. The .wav file names are fixed
in the source code, but the directory may be specified
using --wavdir. Remove this file until there's a demand
for the more precise .wav file mapping.
Fixes: https://github.com/alsa-project/alsa-utils/issues/133 Signed-off-by: Jaroslav Kysela <perex@perex.cz>
Takashi Iwai [Thu, 20 Jan 2022 07:49:17 +0000 (08:49 +0100)]
alsamixer: Fix regression in color setup
The recent change to add the background config broke the color setup
via the config file due. Fix the regression by restoring the
initialization order back again, and changing the logic for the
default background color to be re-initializing color pairs instead.
topology: pre-processor: Move the call to expand variables
Remove the call to snd_config_expand_custom() to expand the top-level
input config. And replace it with calls to snd_config_evaluate_string()
for each non-compound config while processing individual objects. This
will allow retreving variable definitions from object attribute values
and global definitions.
Add a new field "current_obj_cfg" to hold the current object config
being pre-processed.
This will facilitate adding simple math expressions for computing
attribute values for objects based on other attributes. For ex: we can
set the expression for buffer size as follows:
buffer_size "$[($in_channels * 48) * 4]"
The buffer_size attribute value will be computed with the attribute
value "in_channels" based on the expression above. So if $in_channels =
2, buffer_size will be evaluated to 384.
Additionally this change also permits computing attribute values based
on previously computed values. For example:
dma_buffer_size will be computed as 768. Note that the order of
definitions for buffer_size and dma_buffer_size matters because the
evaluation for dma_buffer_size depends on the evaluation of buffer_size.
In order to conform to this, the tplg_object_copy_and_add_param() is
modified to add attribute configs from class config to an object using
snd_config_before() instead of snd_config_add().
With this change, we no longer need to set the auto_attr_updater for
buffer type widget objects. So remove it.
Signed-off-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com> Signed-off-by: Jaroslav Kysela <perex@perex.cz>
Jaroslav Kysela [Mon, 6 Dec 2021 09:13:22 +0000 (10:13 +0100)]
topology: change include path
Add support for relative (based on the path from the parsed
configuration file) and absolute include path without
ALSA_CONFIG_DIR environment variable usage. The dependency
on the alsa-lib config tree may be added on demand.
topology: pre-processor: Add support for conditional includes
Add a new keyword "IncludeByKey" that will be used to conditional
include configuration files based on the argument value supplied during
build time. For example:
topology: Add option to pass pre-processor definitions
Add a -D switch to be able to pass pre-processor definitions that will
be used to expand arguments in the input config file. This will be
useful to generate multiple topology binaries from the same input config
file with different argument values.
For example: if we had a pipeline config as follows:
We can define the variable for DYNAMIC_PIPELINE as:
Define {
DYNAMIC_PIPELINE 0
}
And when pre-processing the conf file pass "-D DYNAMIC_PIPELINE=1" to
override the default value for dynamic_pipeline attribute in the input
conf file.
Signed-off-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com> Signed-off-by: Jaroslav Kysela <perex@perex.cz>
Jaroslav Kysela [Fri, 3 Dec 2021 10:09:54 +0000 (11:09 +0100)]
alsactl: fix the check for additional elements
The driver may export only write-only elements. The previous
heuristics code do not handle this use case correctly.
Iterate through all elements and skip the write-only ones.
Fixes: https://github.com/alsa-project/alsa-utils/issues/122 Signed-off-by: Jaroslav Kysela <perex@perex.cz>
Pavel Hofman [Sun, 24 Oct 2021 08:31:55 +0000 (10:31 +0200)]
alsaloop: Support "Playback Pitch 1000000" rate shift
Linux 5.15 will introduce a new control element "Playback Pitch 1000000"
(commit 6fec018 ("usb: gadget: u_audio.c: Adding Playback Pitch ctl for
sync playback") which provides feedback mechanism for playback direction
of USB Audio Gadget. The control operates in the same way as the
existing control element "Capture Pitch 1000000".
This patch adds support for this feature.
Signed-off-by: Pavel Hofman <pavel.hofman@ivitera.com> Signed-off-by: Jaroslav Kysela <perex@perex.cz>
Pavel Hofman [Sun, 24 Oct 2021 08:31:54 +0000 (10:31 +0200)]
alsaloop: Renamed field capt_pitch to ctl_pitch
Renaming capt_pitch to ctl_pitch to respect the naming style of
snd_ctl_elem_value_t fields in loopback_handle. Also making the variable
name suitable for planned support of playback pitch.
Signed-off-by: Pavel Hofman <pavel.hofman@ivitera.com> Signed-off-by: Jaroslav Kysela <perex@perex.cz>
Jaroslav Kysela [Thu, 28 Oct 2021 10:07:10 +0000 (12:07 +0200)]
alsactl: suppress no device 'errors' for UCM
This patch adds --ucm-nodev (or -X) option to get those
messages back. The code works only with library 1.2.6+.
By default, these messages are suppressed:
alsactl[xxx]: alsa-lib parser.c:242:(error_node) UCM is not supported for this HDA model (HDA Intel PCH...)
alsactl[xxx]: alsa-lib main.c:1405:(snd_use_case_mgr_open) error: failed to import hw:0 use case configuration -6
Takashi Iwai [Wed, 20 Oct 2021 15:13:35 +0000 (17:13 +0200)]
alsamixer: Allow setting the default background color in config
The recent commit c867aa8a84a7 ("alsamixer: use background color
instead of COLOR_BLACK") changed the behavior of alsamixer to take the
system default background color instead of black. This caused
problems on the terminal setups that have bright background colors,
e.g. yellow is very hard to read.
It could be "fixed" by setting up the color configurations in
~/.config/alsamixer.rc, but this needs to change the all colors in
every element, which is pretty cumbersome. Instead, this patch
extends the config set command to allow user to specify the default
background color. A user like me can create their own
~/.config/alsamixer.rc file containing the line
set background black
and the old good black background is back again.
Note that, for achieving the above, we also had to shuffle the
function call order, to parse the config at first, then initialize
curses. This shouldn't matter for other behavior.
Pavel Hofman [Wed, 13 Oct 2021 10:33:43 +0000 (12:33 +0200)]
alsaloop: added option prateshift for PLAYSHIFT ctl elem used in PLAYSHIFT
If snd-aloop device is on playback side, the required sync mode is
PLAYSHIFT. That means Loopback ctl elem "PCM Rate Shift 100000" of the
corresponding capture side of the Loopback pipe must be controlled (by
a reciprocal).
ASCII name of the playback rate shift ctl elem is specified with newly
added option -x/--prateshift, e.g.:
-P hw:Loopback,0 -S playshift \
-x iface=PCM,name='PCM Rate Shift 100000',device=1
Signed-off-by: Pavel Hofman <pavel.hofman@ivitera.com> Signed-off-by: Jaroslav Kysela <perex@perex.cz>
Added -T / --timestamp option (with parameter "realtime", "monotonic" or "raw") which prints
a timestamp before each received message when using the --dump mode.
Fixes: https://github.com/alsa-project/alsa-utils/pull/108 Signed-off-by: Folkert van Heusden <mail@vanheusden.com> Signed-off-by: Jaroslav Kysela <perex@perex.cz>
Takashi Iwai [Tue, 24 Aug 2021 07:36:33 +0000 (09:36 +0200)]
aplay: Handle 16bit sample negative overflow in peak calculations
The handling of 16bit samples in the peak calculations has a bug when
a sample with 0x8000 is passed. As abs() treats 32bit int, it returns
0x8000. And yet the code stores back into 16bit value again.
To fix that overflow, use 32bit value (i.e. val instead of sval) for
the further calculations.
alsaloop: Support "Capture Pitch 1000000" rate shift
In Linux 5.14, a new feedback mechanism for USB Audio
Gadget is introduced (commit e89bb428), along with a
new control element "Capture Pitch 1000000". This patch
adds support for this feature. Note that this property
seems to be the reverse of PCM Rate Shift, so we have
to take reciprocal of pitch.
Signed-off-by: Yunhao Tian <t123yh@outlook.com> Signed-off-by: Jaroslav Kysela <perex@perex.cz>
While instantiating the volume-pipeline class, the pga object
could be modified as follows:
Object.Pipeline.volume-playback.0 {
Object.Widget.pga.0 {
format "s24le"
}
}
When building the pga.0 object in the class definition, merge
the attributes declared in the volume-playback.0 object to create
a new config as follows to make sure that all attributes are
set for the pga object.
Object.Widget.pga.0 {
ramp_step_ms 250
format "s24le"
}
Signed-off-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com> Signed-off-by: Jaroslav Kysela <perex@perex.cz>
topology: pre-process-object: Add support for pre-process objects with no builder
Some objects just need tobe processed to add their attributes
to the private data section of their parent objects.
An example of this would be the pdm_config objects for
DMIC DAI's. Each pdm_config object's attributes need
to be added as separate arrays in the DAI object's
private data.
Modify the signature of tplg_add_object_data() to pass
the array_name parameter when multiple objects of the
same type in the same parent are processed.
Signed-off-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com> Signed-off-by: Jaroslav Kysela <perex@perex.cz>
Chao Song [Wed, 2 Jun 2021 05:20:49 +0000 (13:20 +0800)]
topology: pre-process-object: add support for updating automatic attributes
Classes definitions in Topology2.0 can have attributes
qualified with the "automatic" constraint. Values for
these attributes will be calculated by the compiler.
This patch provides a generic method for defining automatic
attributes computation logic for different classes.
To update automatic attributes for a class, add an item
in object_build_map with auto_attr_updater defined, and then
add updating logic in the custom auto_attr_updater function.
Signed-off-by: Chao Song <chao.song@linux.intel.com> Signed-off-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com> Signed-off-by: Jaroslav Kysela <perex@perex.cz>
Jaroslav Kysela [Mon, 14 Jun 2021 10:22:08 +0000 (12:22 +0200)]
arecord: Inform users when 8-bit sampling is used on tty
When we reverted 0c5948e ("aplay: try to use 16-bit format to
increase capture quality"), we should also handle the original
problem somehow. This code shows a warning with a hint to
the right parameter.
Fixes: https://github.com/alsa-project/alsa-utils/issues/96 Signed-off-by: Jaroslav Kysela <perex@perex.cz>
Andrea Piras [Fri, 29 Nov 2019 02:13:21 +0000 (03:13 +0100)]
added an option to aseqnet to optionally set the midi process name
This option allows to run multiple instances of aseqnet without having
to double check the assigned port number, since each one can get spawned
with a unique name.
Fixes: https://github.com/alsa-project/alsa-utils/pull/95 Signed-off-by: Andrea Piras <andrea.piras.85@gmail.com> Signed-off-by: Jaroslav Kysela <perex@perex.cz>
Andreas Müller [Thu, 3 Jun 2021 14:07:10 +0000 (16:07 +0200)]
utils.c: Include limits.h explicitly to fix build on musl
Fixes:
| ../../alsa-utils-1.2.5/alsactl/utils.c: In function 'snd_card_clean_cfgdir':
| ../../alsa-utils-1.2.5/alsactl/utils.c:309:19: error: 'PATH_MAX' undeclared (first use in this function)
| 309 | char path[PATH_MAX];
| | ^~~~~~~~
| ../../alsa-utils-1.2.5/alsactl/utils.c:309:19: note: each undeclared identifier is reported only once for each function it appears in
Fixes: https://github.com/alsa-project/alsa-utils/pull/92 Signed-off-by: Andreas Müller <schnitzeltony@gmail.com> Signed-off-by: Jaroslav Kysela <perex@perex.cz>
Sören Tempel [Sun, 6 Jun 2021 01:14:19 +0000 (03:14 +0200)]
alsactl: load_state: Only delete config if one was loaded
If load_configuration fails with open_failed == true, load_state will
jump to the out label without config being initialized and pass this
uninitialized config value to snd_config_delete. This commit fixes this
issue by initializing config with NULL and checking if it is non-null
before invoking snd_config_delete.
Fixes: https://github.com/alsa-project/alsa-utils/pull/94 Fixes: f138117 ("alsactl: load_state() - initialize config variable for the open_failed case") BugLink: https://github.com/alsa-project/alsa-utils/issues/93 Signed-off-by: Sören Tempel <soeren+git@soeren-tempel.net> Signed-off-by: Jaroslav Kysela <perex@perex.cz>
Chao Song [Mon, 31 May 2021 02:29:57 +0000 (10:29 +0800)]
topology: fix potential null pointer from strchr
This patch adds check to the return pointer from strchr,
because it may be null and cause segment fault, if component
is not properly constructed.
Fixes: https://github.com/alsa-project/alsa-utils/pull/91 Signed-off-by: Chao Song <chao.song@linux.intel.com> Signed-off-by: Jaroslav Kysela <perex@perex.cz>
topology: pre-process-object: add support for prepocessing child objects
Add support for processing object instances embedded
within objects and classes. For example:
Object.Control.mixer."0" {
#Channel register and shift for Front Left/Right
Object.Base.channel."fl" {
shift 0
}
Object.Base.channel."fr" {
}
Object.Base.ops."ctl" {
info "volsw"
#256 binds the mixer control to volume get/put handlers
get 256
put 256
}
}
and pga class embeds the mixer objects as follows:
Class.Widget."pga" {
...
Object.Control {
mixer."0" {...}
mixer."1" {...}
}
The pre-processor starts with the top-pevel PGA widget object
and processes the mixer objects in the class definition.
This will recursively pre-processes its child objects to add the channels,
tlv and ops.
Signed-off-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com> Signed-off-by: Jaroslav Kysela <perex@perex.cz>
topology: pre-process-dai: add support for PCM and BE DAI objects
Add support for pre-processing PCM and BE DAI objects:
Object.PCM.pcm."0" {
name "Port0"
direction "duplex"
}
will be converted to:
SectionPCM.'Port0' {}
The capabilities and dai configs will be added those objects are pre-processed.
An ex of DAI object would be:
Object.Dai.SSP."0" {
direction "duplex"
stream_name "NoCodec-0"
id 0
default_hw_conf_id 0
format "s24le"
quirks "lbm_mode"
sample_bits 24
}
converted to:
SectionBE {
'SSP.0.duplex' {
id 0
stream_name NoCodec-0
default_hw_conf_id 0
data [
'SSP.0.duplex.sof_tkn_intel_ssp.word'
'SSP.0.duplex.sof_tkn_dai.word'
'SSP.0.duplex.sof_tkn_dai.string'
'SSP.0.duplex.sof_tkn_intel_ssp.short'
]
}
Signed-off-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com> Signed-off-by: Jaroslav Kysela <perex@perex.cz>
If the source/sink names are references to objects within a parent pipeline
object, the index attribute value can be skipped and it will be
populated when the object is pre-processed
The reference pga..0 will need to be resolved to
get the widget name pga.1.0 and buffer..0 will
be resolved to buffer.1.0 before creating the SectionGraph as follows:
Object.Base.ops."ctl" {
info "volsw"
#256 binds the mixer control to volume get/put handlers
get 256
put 256
}
access [
read_write
tlv_read
]
}
}
Would be converted to:
SectionControlMixer.'2 Master Playback Volume' {
index 2
max 32
channel {
fl {
reg 1
}
fr {
reg 1
shift 1
}
}
tlv "vtlv_m64s2"
ops.0 {
info volsw
get 256
put 256
}
access [
read_write
tlv_read
]
}
and the SectionWidget for pga.2.0 would be updated to add the mixer references as follows:
SectionWidget.'pga.2.0' {
...
mixer [
"2 Master Playback Volume"
]
}
Signed-off-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com> Signed-off-by: Jaroslav Kysela <perex@perex.cz>
topology: pre-process-base: add support for VendorToken objects
Add support for pre-processing VendorToken objects.
For ex:
Object.Base.VendorToken."sof_tkn_dai" {
dmac_config 153
dai_type 154
index 155
direction 156
}
would be converted to:
SectionVendorTokens."sof_tkn_dai" {
dmac_config 153
dai_type 154
index 155
direction 156
}
Signed-off-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com> Signed-off-by: Jaroslav Kysela <perex@perex.cz>
topology: pre-process-object: Add support for data objects
Pre-process data objects, create the SectionData and update
the parent object with the reference to the object.
For example, the following object instance:
topology: pre-process-obejct: add helper function to get the section config
Add a helper function to retrieve the config node
pointing to the section name for a given object.
For ex: for the object, Object.Widget.pga.1{},
the function returns the config with id, "SectionWidget"
in the output config.
Signed-off-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com> Signed-off-by: Jaroslav Kysela <perex@perex.cz>
topology: pre-process-object: add data section for attributes with token reference
Objects that have attributes with token_ref need
to have separate SectionData and SectionVendorTuples
for each unique token_ref based on the attribute_sets
in the object's attribute_set_list.
Add the tplg_pp_add_object_data()
function to add the data[] refs in the object and also
the respective SectionData and SectionVendorTuples.
The following sections will be added:
SectionWidget.'pga.2.0' {
index 2
type pga
no_pm 1
mixer [
"2 Master Playback Volume"
]
bytes [
]
data [
"pga.2.0.sof_tkn_comp.word"
"pga.2.0.sof_tkn_comp.string"
"pga.2.0.sof_tkn_comp.uuid"
"pga.2.0.sof_tkn_volume.word"
]
}
topology: pre-process-object: Add support for processing Manifest object
The pre-processor converts the Topology2.0 objects into
the relevant sections by looking for attributes defined
in the template config for the section and reading the
attribute values from the object instance config.
The structure struct build_function_map contains the
mapping of the build function to use for each object
based on the type and name for the class that the object
belongs to. The manifest object is the simplest with
no attributes. So, the build function simply creates
a new Section called SectionManifest which will be
populated with the data section in the following patches.
Signed-off-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com> Signed-off-by: Jaroslav Kysela <perex@perex.cz>
topology: pre-process-object: construct object name from its constructor attributes
An object's name is derived from its constructor attribute
values separated by '.'. For example, the name for the
host widget objects is derived from its index and direction
attribute values as follows:
Object.Widget.host."playback" {
index 2
}
The name for the host widget object would be host.2.playback.
Alternatively, if the object has a name attribute, the class
definition may skip the constructor attributes and the name attribute
value will be used instead.
Signed-off-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com> Signed-off-by: Jaroslav Kysela <perex@perex.cz>
Attributes can have constraints set for valid values, min
or max values. If the attribute value is set in an object,
the value must be validated against the set constraints.
An example for attribute constraint would be:
DefineAttribute."direction" {
constraints {
valid_values [
"playback"
"capture"
]
tuple_values [
0
1
]
}
}
where the tuple_values array would translate the valid_values of
playback as 0 and capture as 1.
Signed-off-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com> Signed-off-by: Jaroslav Kysela <perex@perex.cz>
topology/pre-process-object: update object config with attributes
Object attributes can be set in multiple places. Search for
the attribute value in the following order:
1. Value set in object instance
2. Default value set in the object's class definition
3. Inherited value from the parent object
4. Value set in the object instance embedded in the parent object
5. Value set in the object instance embedded in the parent class definition
Mandatory attributes must be found in one of the above, resulting
in an error if not found.
Signed-off-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com> Signed-off-by: Jaroslav Kysela <perex@perex.cz>
topology: pre-process-object: Add support for pre-processing Objects
Add support for pre-processing object instances in the input
config. An object's attributes can be set in multiple places
such as, within the object instance, default values in the class
defnition, inherited from a parent object or explicitly set
in a parent object. Before converting the object config into
the relevant section in the existing syntax, all the attribute
values must be consolidated into one place so that it is easy
to verify if all mandatory attributes are set.
Also, the name of the object will be constructed from the
attributes defined in the attributes.constructor[] config
in the class definition and the unique attribute's value
must be set from the value passed in the object instance.
This patch create a temporary config for each object instance
and populates its unique attribute value. The rest of the steps
will be added in the following patches.
Signed-off-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com> Signed-off-by: Jaroslav Kysela <perex@perex.cz>
topology: pre-process-class: function to get attribute type
Add a helper function to get attribute type from the
attribute definition and convert them to SND_CONFIG_TYPE_*
values. When no type if provided for an attribute, type
defaults to integer.
Signed-off-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com> Signed-off-by: Jaroslav Kysela <perex@perex.cz>
topology: pre-process-class: add funcion to get the name of the unique attribute in a class
Every class must have a unique attribute that will be used
to instantiate the object. The value provided for this
attribute must be unique within the same alsaconf node for
objects of the same class. Add a helper function to get the
name of the attribute that must have a unique value in the
object instance.
For example, when instantiating 2 buffer widgets within a pipeline,
they must be given unique instance attribute values as:
Object.Widget.buffer.0{} and Object.Widget.buffer.1{}.
Signed-off-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com> Signed-off-by: Jaroslav Kysela <perex@perex.cz>
topology: pre-process-class: Add functions to check attribute constraints
Add helper functions to check if an attribute is
mandatory, immutable or unique in the class definition.
ex: for a host widget component, these are defined
as follows:
attributes {
#
# host objects instantiated within the same alsaconf node must have unique
# direction attribute
#
unique "direction"
mandatory [
"type"
"stream_name"
]
immutable [
"uuid"
]
}
Signed-off-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com> Signed-off-by: Jaroslav Kysela <perex@perex.cz>
topology: pre-process-class: Add helper function to look up class definition
Add a helper function to look up the class definition for
an object. ex: for an object instance, Object.Widget.pga.0{}, the
function returns the config pointing to Class.Widget.pga{} in
the input conf.
Signed-off-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com> Signed-off-by: Jaroslav Kysela <perex@perex.cz>
topology: pre-processor: Add a helper function to concat strings
The pre-processor needs to concatinate strings separated
by '.' for building object names from constructor attribute
values and searching for configs with ID's containing strings
separate by '.'. Add a helper function to concat strings in
the specified input format.
Signed-off-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com> Signed-off-by: Jaroslav Kysela <perex@perex.cz>
topology: Add support for pre-processing Topology2.0 syntax
This patch adds support for pre-processing the Topology2.0.
The '-p' switch add pre-processing support during compilation
and the '-P' switch is for converting the Topology2.0
configuration file into the existing syntax.
Topology2.0 is a high level keyword extension on top of the existing ALSA
conf topology format designed to:
1) Simplify the ALSA conf topology definitions by providing high level
"classes" so topology designers need to write less config for common
object definitions.
2) Allow simple reuse of objects. Define once and reuse (like M4) with
the ability to alter objects configuration attributes from defaults.
3) Allow data type and value verification. This is not done today and
frequently crops up in FW bug reports.
Common Topology Classes
-----------------------
Topology today has some common classes that are often reused throughout
with slightly altered configurations. i.e. widgets (components),
pipelines, dais and controls.
Topology2.0 introduces the high level concept of reusable "class" like
definition for that can be used to create topology objects.
Common Topology Attributes
--------------------------
Topology defines a lot of attributes per object with different types
and constraints. Today there is no easy way to validate type or
constraints and this can lead to many hard to find problems in FW at
runtime.
A new keyword "DefineAttribute" has been added to define attribute
constraints such as min value, max value, enum_values etc. This
then allows alsatplg to validate each topology object attribute.
Topology Classes define the list of attributes that they use and
whether the attribute is mandatory, can be overridden by parent users
or is immutable. This also helps alsatplg emit the appropriate errors
for attribute misuse.
Class constructor attributes
----------------------------
Some attributes in the class definition are declared as constructor
attributes and these will be used to construct the name of the object.
For ex: for the host widget, the index and direction are constructor
attributes and the name for the widget is derived as follows:
host.1.playback or host.2.capture etc.
Attribute Inheritance:
----------------------
One of the key features of Topology2.0 is how the attribute values are
propagated from a parent object to a child object. For ex: a pipeline
object can pass down the pipeline_id attribute to all its widgets.
Inheritance is implicit when an object and its embedded child objects
have matching names for a attribute/argument. Attribute values
set explicitly in an object instance always has precedence over
the values inherited from the parent object.
git://git.alsa-project.org / alsa-utils.git / log