The SND_SOC_DAPM_PRE_PMU case would call startup()/hw_params() that
might access substream->runtime through other functions.
For example:
Unable to handle kernel NULL pointer dereference at virtual address
[....]
PC is at snd_pcm_hw_rule_add+0x24/0x1b0
LR is at snd_pcm_hw_constraint_list+0x20/0x28
[....]
Process arecord (pid: 424, stack limit = 0xffffffc1ecaf0020)
Call trace:
[<ffffffc00086be68>] snd_pcm_hw_rule_add+0x24/0x1b0
[<ffffffc00086c014>] snd_pcm_hw_constraint_list+0x20/0x28
[<ffffffc0008b47a4>] cs53l30_pcm_startup+0x24/0x30
[<ffffffc0008a6260>] snd_soc_dai_link_event+0x290/0x354
[<ffffffc0008a7528>] dapm_seq_check_event.isra.31+0x134/0x2c8
[<ffffffc0008a7768>] dapm_seq_run_coalesced+0x94/0x1c8
[<ffffffc0008a7940>] dapm_seq_run+0xa4/0x404
[<ffffffc0008a8bac>] dapm_power_widgets+0x524/0x984
[<ffffffc0008ab1c4>] snd_soc_dapm_stream_event+0x8c/0xa8
[<ffffffc0008ac7f4>] soc_pcm_prepare+0x10c/0x1ec
[<ffffffc000865b9c>] snd_pcm_do_prepare+0x1c/0x38
[<ffffffc000865600>] snd_pcm_action_single+0x40/0x88
[<ffffffc0008656b8>] snd_pcm_action_nonatomic+0x70/0x90
[<ffffffc000868d28>] snd_pcm_common_ioctl1+0xb6c/0xdd8
[<ffffffc000869508>] snd_pcm_capture_ioctl1+0x200/0x334
[<ffffffc00086a084>] snd_pcm_ioctl_compat+0x648/0x95c
[<ffffffc0001ff4b4>] compat_SyS_ioctl+0xac/0xfc4
[<ffffffc000084cf0>] el0_svc_naked+0x24/0x28
---[ end trace 0dc4f99c2759c35c ]---
So this patch adds a dummy runtime for the original dummy substream
to merely avoid the NULL pointer access.
Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
This is useful outside the core, when one dapm element is added
at a time.
Signed-off-by: Subhransu S. Prusty <subhransu.s.prusty@intel.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
In is_connected_ep, when custom_stop_condition is true, need to
return the correct paths instead of con which is 0.
Fixes: 6742064aef7f('ASoC: dapm: support user-defined stop condition in dai_get_connected_widgets')
Signed-off-by: Jeeja KP <jeeja.kp@intel.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Certain situations may warrant examining DAPM paths only to a certain
arbitrary point, as opposed to always following them to the end. For
instance, when establishing a connection between a front-end DAI link
and a back-end DAI link in a DPCM path, it does not make sense to walk
the DAPM graph beyond the first widget associated with a back-end link.
This patch introduces a mechanism which lets a user of
dai_get_connected_widgets supply a function which will be called for
every node during the graph walk. When invoked, this function can
execute arbitrary logic to decide whether the walk, given a DAPM widget
and walk direction, should be terminated at that point or continued
as normal.
Signed-off-by: Piotr Stankiewicz <piotrs@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
The dummy component is reused for all cards so we special case and don't
bind it to any of them. This means that code like that displaying the
component widgets that tries to look at the card will crash. In the
future we will fix this by ensuring that the dummy component looks like
other components but that is invasive and so not suitable for a fix.
Instead add a special case check here.
Reported-by: Harry Pan <harry.pan@intel.com>
Suggested-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org
This patch fixes coccicheck report:
Unneeded variable: "ret". Return "0" on line 2817
Remove unneccesary variable ret created to return zero.
Signed-off-by: Rajan Vaja <rajan.vaja@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
snd_soc_dapm_dai_link_get() and _put() access the associated ctl
values as value.integer.value[]. However, this is an enum ctl, and it
has to be accessed via value.enumerated.item[]. The former is long
while the latter is unsigned int, so they don't align.
Fixes: c66150824b ('ASoC: dapm: add code to configure dai link parameters')
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Mark Brown <broonie@kernel.org>
When a DAPM context has a prefix the autodisable widgets get prefixed
twice, once for the control and once for the widget. To avoid this use
the un-prefixed control name to construct the autodisable widget name.
This change is purely cosmetic.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@kernel.org>
Always on widgets currently have some odd interactions with DAPM.
Enabling/disabling a widget (snd_soc_dapm_enable_pin) then connecting
it to a path works as expected, ie. when the widget is disabled the
path doesn't power up and it does when the widget is enabled. However
once in a path enabling the widget does not cause anything to power
up, dapm_widget_set_power will return the current power state of the
widget as 1, meaning we never check peer power states.
This patch updates dapm_always_on_check_power to return w->connected
such that it is effected by snd_soc_dapm_enable_pin and the like.
Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
DAPM models various widgets but lacks a sink widget.
DSPs can have modules which take audio data, process it and are
capable of generating events thus acting as a sink of data.
To make the dapm graph complete for such paths we need a dapm
sink widget for these modules, so add a SND_SOC_DAPM_SINK to
declare such a widget. This widget will be treated as
SND_SOC_DAPM_EP_SINK endpoint in the dapm graph
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Reviewed-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@kernel.org>
Currently the number of DAI links is statically defined by the machine
driver at build time using an array. This makes it difficult to shrink/
grow the number of DAI links at runtime in order to reflect any changes
in topology.
We can change the DAI link array in the core to a list so that PCMs and
FE DAI links can be added and deleted at runtime to reflect changes in
use case and DSP topology. The machine driver can still register DAI links
as an array.
As the 1st step, this patch change the PCM runtime array to a list. A new
PCM runtime is added to the list when a DAI link is bound successfully.
Later patches will further implement the DAI link list.
More:
- define snd_soc_new/free_pcm_runtime() to create/free a runtime.
- define soc_add_pcm_runtime() to add a runtime to the rtd list.
- define soc_remove_pcm_runtimes() to clean up the runtime list.
- traverse the rtd list to probe the link components and dais.
- Add a field "num" to PCM runtime struct, used to specify the device
number when creating the pcm device, and for a soc card to access
its dai_props array.
- The following 3rd party machine/platform drivers iterate the rtd list
to check the runtimes:
sound/soc/intel/atom/sst-mfld-platform-pcm.c
sound/soc/intel/boards/cht_bsw_rt5645.c
sound/soc/intel/boards/cht_bsw_rt5672.c
sound/soc/intel/boards/cht_bsw_max98090_ti.c
Signed-off-by: Mengdong Lin <mengdong.lin@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
If there is anything in damp->path_source_cache or
damp->path_sink_cache, it can not be valid after the widgets have been
freed. Without this patch a repeated remove and load of a machine
driver may cause NULL pointer reference in dapm_wcache_lookup() when a
freed widget, not belonging to any list, is haunting in the wcache.
Signed-off-by: Jyri Sarha <jsarha@ti.com>
Reported-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Given a kcontrol, we may want to access the parent widget
and it's associated data. So export function to return it.
Signed-off-by: Mythri P K <mythri.p.k@intel.com>
Signed-off-by: Jeeja KP <jeeja.kp@intel.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
For DAI link events, DSPs would like to get notified for startup
and shutdown event as well apart for existing hw_params. This
helps managing DSP resource allocation and freeup on these events
So add support for startup and shutdown for
snd_soc_dai_link_event()
Signed-off-by: Jeeja KP <jeeja.kp@intel.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
For DSPs we can define processing blocks as DAPM PGA widgets.
Some of these proceesing blocks can be configured by usermode
like EQ etc. So we need to add support of kcontrol for PGA
widgets.
Signed-off-by: Jeeja KP <jeeja.kp@intel.com>
Signed-off-by: Mythri P K <mythri.p.k@intel.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Incase of an unknown event we were directly returning but we missed
freeing params.
Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
A number of functions and structures in the sound subsystem had incomplete
and/or obsolete DocBook comments, leading to warnings when the docs were
built. Correct those comments so that we can enjoy our audio in the
absence of warning noise.
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Mark Brown <broonie@kernel.org>
The snd_soc_dapm_input_path and snd_soc_dapm_output_path trace events are
identical except for the direction. Instead of having two events have a
single one that has a field that contains the direction.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@kernel.org>
After the recent cleanups and generalizations of the DAPM algorithm the
handling of input and output paths is now fully symmetric. This means by
making some slight changes to the data structure and using arrays with one
entry for each direction, rather than separate fields, it is possible to
create a generic implementation that is capable of handling both input and
output paths.
Unfortunately this generalization significantly increases the code size on
the hot path of is_connected_{input,output}_ep() and
dapm_widget_invalidate_{input,output}_paths(), which has a negative impact
on the overall performance. The inner loops of those functions are quite
small and the generic implementation adds extra pointer arithmetic in a few
places.
Testing on ARM shows that the combined code size of the specialized
functions is about 50% larger than the generalized function in relative
numbers. But in absolute numbers its less than 200 bytes, which is still
quite small. On the other hand the generalized function increases the
execution time of dapm_power_one_widget() by 30%. Given that this function
is one of the most often called functions of the DAPM framework the
trade-off of getting better performance at expense of generating slightly
larger code at seems to be worth it.
To avoid this still keep two versions of these functions around, one for
input and one for output. But have a generic implementation of the
algorithm which gets inlined by those two versions. And then let the
compiler take care of optimizing it and removing he extra instructions.
This still reduces the source code size as well as the makes making changes
to the implementation more straight forward since the same change does no
longer need to be done in two separate places. Also on the slow paths we
can use a generic implementations that handle both input and output paths.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@kernel.org>
Make sure to unlock the DAPM mutex when dapm_widget_list_create() fails.
This means the function will now generate a trace_snd_soc_dapm_connected
event, even if the creation of the list fails. But that was the behavior
before the patch that introduced the unlock issue, so that should be fine.
Fixes: 1ce43acff0 ("ASoC: dapm: Simplify list creation in dapm_dai_get_connected_widgets()")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@kernel.org>
Add helper iterator macros for iterating over the source and sink paths of
widget. This will make it easier to change the implementation later on.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@kernel.org>
When running dapm_dai_get_connected_widgets() currently in
is_connected_{input,output}_ep() for each widget that gets added the array
is resized and the code also loops over all existing entries to avoid
adding a widget multiple times.
The former can be avoided by collecting the widgets in a linked list and
only once we have all widgets allocate the array.
The later can be avoided by changing when the widget is added. Currently it
is added when walking the neighbor lists of a widget. Since a widget can be
neighbors with multiple other widgets it could get added twice and hence
the check is necessary. But the main body of is_connected_{input,output}_ep
is guaranteed to be only executed at most once per widget. So adding the
widget to the list at the beginning of the function automatically makes
sure that each widget gets only added once. The only difference is that
using this method the starting point itself will also end up on the list,
but it can easily be skipped when creating the array.
Overall this reduces the code size and speeds things slightly up.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@kernel.org>
list_first_entry() always returns non NULL and since the code previously
checked that list is not empty it will also be a valid pointer. Furthermore
a path has always a sink or a source widget. So both checks are redundant
and can be removed.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@kernel.org>
When creating a new widget from a template the name string of the template
is duplicated for the newly created widget. This is necessary because in
some cases the string might be stored on the stack or other volatile
memory locations.
But most of the time the string is static const data, which means it is
possible to use it directly without having to worry that it might get freed
or changed.
Use kstrdup_const() to handle duplicating the string. This function is
capable of detecting whether a string is immutable and if it is returns the
input without duplicating it. This will slightly reduce the runtime memory
footprint of DAPM and also speed up initialization.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@kernel.org>
snd_soc_tplg_widget_remove_all() has a verbatim copy of an older version of
the widget freeing code from dapm_free_widgets(). Add a new helper function
that takes care of freeing a widget and use it in both places.
This removes the duplicated code and also makes sure that future changes to
the widget freeing code only have to be made in one location.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@kernel.org>
Commit fdb6eb0a12 ("ASoC: dapm: Modify widget stream name according to
prefix") fixed the case where a DAPM route between a DAI widget and a
DAC/ADC/AIF widget with a matching stream name was not created when the
DAPM context was using a prefix.
Unfortunately the patch introduced a few issues on its own like leaking the
dynamically allocated stream name memory and also not checking whether the
allocation succeeded in the first place.
It is also incomplete in that it still does not handle the case where
stream name of the widget is a substring of the stream name of the DAI,
which is explicitly allowed and works fine if no DAPM prefix is used.
Revert the commit and take a slightly different approach to solving the
issue. Instead of comparing the widget's stream name to the name of the DAI
widget compare it to the stream name of the DAI widget. The stream name of
the DAI widget is identical to the name of the DAI widget except that it
wont have the DAPM prefix added. So this approach behaves identical
regardless to whether the DAPM context uses a prefix or not.
We don't have to worry about potentially matching with a widget with the
same stream name, but from a different DAPM context with a different
prefix, since the code already makes sure that both the DAI widget and the
matched widget are from the same DAPM context.
Fixes: fdb6eb0a12 ("ASoC: dapm: Modify widget stream name according to prefix")
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org
The name field of the widget template is only used inside
snd_soc_dapm_new_control_unlocked() which allocates a copy for the actual
widget. This means we need to free the name allocated for the template in
dapm_kcontrol_data_alloc() and not the name of the actual widget in
dapm_kcontrol_free(). Otherwise we get a double free on the widget name and
a memory leak on the template name.
Fixes: 773da9b358 ("ASoC: dapm: Append "Autodisable" to autodisable widget names")
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@kernel.org>
Dummy dai can be used by multiple sound card. But it only belong to one
card's dapm list. If another card use it, there will be dapm_assert_locked
warning.
[ 20.015782] WARNING: CPU: 1 PID: 661 at sound/soc/soc-dapm.c:124 dapm_assert_locked.isra.36+0x4c/0x58()
[ 20.025249] Modules linked in:
[ 20.028349] CPU: 1 PID: 661 Comm: aplay Not tainted 4.1.0-rc6-next-20150605-00004-gaee05d8-dirty #92
[ 20.037528] Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree)
[ 20.044110] Backtrace:
[ 20.046614] [<80012e00>] (dump_backtrace) from [<80012fa0>] (show_stack+0x18/0x1c)
[ 20.054229] r6:809e8060 r5:00000000 r4:00000000 r3:00000000
[ 20.060002] [<80012f88>] (show_stack) from [<807a0f74>] (dump_stack+0x80/0x9c)
[ 20.067293] [<807a0ef4>] (dump_stack) from [<8002b144>] (warn_slowpath_common+0x7c/0xb4)
[ 20.075427] r5:0000007c r4:00000000
[ 20.079065] [<8002b0c8>] (warn_slowpath_common) from [<8002b1a0>] (warn_slowpath_null+0x24/0x2c)
[ 20.087898] r8:00000001 r7:88007c28 r6:ed94a680 r5:809e83e4 r4:ed83d6c0
[ 20.094747] [<8002b17c>] (warn_slowpath_null) from [<8058403c>] (dapm_assert_locked.isra.36+0x4c/0x58)
[ 20.104101] [<80583ff0>] (dapm_assert_locked.isra.36) from [<805842ec>] (dapm_mark_dirty+0x64/0xa4)
[ 20.113165] [<80584288>] (dapm_mark_dirty) from [<805853a8>] (soc_dapm_dai_stream_event.isra.42+0x30/0xc8)
[ 20.122863] r8:ed9b5dbc r7:00000000 r6:00000001 r5:00000001 r4:ed83d6c0
[ 20.129706] [<80585378>] (soc_dapm_dai_stream_event.isra.42) from [<80587e28>] (snd_soc_dapm_stream_event+0x78/0xa0)
[ 20.140264] r5:ee2ee62c r4:00000001
[ 20.143918] [<80587db0>] (snd_soc_dapm_stream_event) from [<8058957c>] (soc_pcm_prepare+0x138/0x21c)
[ 20.153058] r8:ed8d9480 r7:00000000 r6:ed9b0e00 r5:00000001 r4:ee2ee62c r3:00000000
...
This patch is to not probe the dummy component in soc_probe_component. Then
there is no widget created for dummy DAI, and also don't need to check the
dummy dai in dapm_connect_dai_link_widgets().
Signed-off-by: Shengjiu Wang <shengjiu.wang@freescale.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
There is nothing snd_soc_codec specific in this function, just use
snd_soc_component instead.
With this also the last reference of snd_soc_codec form soc-dapm.c.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@kernel.org>
The DAPM lock must be held when accessing the DAPM graph status through
sysfs or debugfs, otherwise concurrent changes to the graph can result in
undefined behaviour.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org
The commit 02aa78abec ("ASoC: DAPM: Add APIs to create individual DAPM
controls.") added locking to the snd_soc_dapm_new_control function but
did not update the call to snd_soc_dapm_new_control in the auto-disable
mux code, this appears to be because the patches were sent at fairly
similar times.
This patch change the call in the auto-disable mux code to use the new
snd_soc_dapm_new_control_unlocked function instead.
Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Fix the following error:-
All error/warnings (new ones prefixed by >>):
>
> sound/built-in.o: In function `soc_tplg_dapm_widget_create':
> >> :(.text+0x25a90): undefined reference to `snd_soc_dapm_new_control'
Signed-off-by: Liam Girdwood <liam.r.girdwood@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
The change fixes the following compilation problem:
sound/soc/soc-dapm.c: In function 'dapm_kcontrol_data_alloc':
sound/soc/soc-dapm.c:388:4: error: implicit declaration of function
'snd_soc_dapm_new_control' [-Werror=implicit-function-declaration]
data->widget = snd_soc_dapm_new_control(widget->dapm,
^
sound/soc/soc-dapm.c:387:17: warning: assignment makes pointer
from integer without a cast [enabled by default]
data->widget = snd_soc_dapm_new_control(widget->dapm,
^
sound/soc/soc-dapm.c: At top level:
sound/soc/soc-dapm.c:3269:1: error: conflicting types for
'snd_soc_dapm_new_control'
snd_soc_dapm_new_control(struct snd_soc_dapm_context *dapm,
^
In addition to the fix add static qualifier to
snd_soc_dapm_new_control() function to silence checkpatch.
Fixes: 02aa78abec ("ASoC: DAPM: Add APIs to create individual DAPM controls.")
Signed-off-by: Vladimir Zapolskiy <vz@mleia.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
The topology core needs to be able to create individual widget controls at
runtime and driver init. Add a regular locked and unlocked API calls to
facilitate this requirement.
The unlocked call is used by the topology core during component driver
probing where the card dapm_mutex is held by the ASoC core and the locked
version at non component driver probe time.
Signed-off-by: Liam Girdwood <liam.r.girdwood@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
When there is prefix specified, currently we will add this prefix in
widget->name, but not in widget->sname.
it causes failure at snd_soc_dapm_link_dai_widgets:
if (!w->sname || !strstr(w->sname, dai_w->name))
because dai_w->name has prefix added, but w->sname does not.
We should also add prefix for stream name
Signed-off-by: Koro Chen <koro.chen@mediatek.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org
Some CODECs have a significant number of DAPM routes and for each route,
when it is added to the card, the entire card widget list must be
searched. When adding routes it is very likely, however, that adjacent
routes will require adjacent widgets. For example all the routes for a
mux are likely added in a block and the sink widget will be the same
each time and it is also quite likely that the source widgets are
sequential located in the widget list.
This patch adds a cache to the DAPM context, this cache will hold the
source and sink widgets from the last call to snd_soc_dapm_add_route for
that context. A small search of the widget list will be made from those
points for both the sink and source. Currently this search only checks
both the last widget and the one adjacent to it.
On wm8280 which has approximately 500 widgets and 30000 routes (one of
the largest CODECs in mainline), the number of paths that hit the cache
is 24000, which significantly improves probe time.
Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Currently snd_soc_dapm_add_route will continue to search the widget list
even after both the source and sink for the route have been located.
This patch breaks out of the search when both are located giving a
small improvement in probe time for drivers.
Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
The is a missing mutex unlock on the error path in
snd_soc_dapm_get_enum_double. This was introduced in commit
561ed680b7 ("ASoC: dapm: Add support for autodisable mux controls").
This patch adds the missing unlock.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
A demux is conceptually similar to a mux. Where a mux has multiple input
and one output and selects one of the inputs to be connected to the output,
the demux has one input and multiple outputs and selects one of the outputs
to which the input gets connected.
This similarity makes it straight forward to support them in DAPM using the
existing mux support, we only need to swap sinks and sources when initially
setting up the paths.
The only slightly tricky part is that there can only be one control per
path. Since mixers/muxes are at the sink of a path and a demux is at the
source and both types want a control it is not possible to directly connect
a demux output to a mixer/mux input. The patch adds some sanity checks to
make sure that this does not happen.
Drivers who want to model hardware which directly connects a demux output
to a mixer/mux input can do this by inserting a dummy widget between the
two. E.g.:
{ "Dummy", "Demux Control", "Demux" },
{ "Mixer", "Mixer Control", "Dummy" },
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@kernel.org>
Nicolin Chen