drivers: dai: Add virtual DAI driver and tests #95233

SurajSonawane2415 · 2025-08-31T15:50:39Z

This PR is part of the GSoC 2025 Project: Add Virtual DAI Component to SOF and is based on SOF Issue #9349.

We introduce a new DAI_VIRTUAL type with driver its associated support to enable audio pipelines that do not rely on physical DAI hardware. This is useful in the following scenarios:

Debugging and rapid prototyping: Quickly create and test audio pipelines without needing actual hardware.
Software loopback preparation: Lays the groundwork for a memory-to-memory audio pipeline within SOF.

Key Changes

Added Virtual DAI driver (initial version with basic logs).
Added DTS binding (dai-virtual.yaml).
Updated Kconfig/CMake and integrated with i.MX8M DTS.
Added ztest-based test suite for basic API validation.

Testing

Platform: i.MX8MP EVK with Virtual DAI topology.
Environment: Zephyr-based SOF build.
Results:
- NoCodec card + Virtual DAI detected.
- Probe, config, and removal flows working as expected.
- All test cases executed successfully, all tests passed

Logs:

*** Booting Zephyr OS build 6e3ea447cbfb ***
[00:00:00.046,014] <inf> main: SOF on imx8mp_evk
[00:00:00.051,043] <inf> main: SOF initialized
[00:00:00.055,909] <inf> ipc: ipc: new cmd 0x90030000
[00:00:00.061,749] <inf> ipc: ipc: new cmd 0x30100000
[00:00:00.066,973] <inf> pipe: pipeline new pipe_id 1 priority 0
[00:00:00.074,086] <inf> ipc: ipc: new cmd 0x30010000
[00:00:00.079,312] <inf> ipc: comp new 0x924549b4U type 2 id 1.4
[00:00:00.085,734] <inf> dai_comp: DAIZ: dai_new()
[00:00:00.090,941] <inf> dai_comp: DAIZ: dai_common_new()
[00:00:00.096,757] <inf> virtual_dai: virtual_dai_config_get
[00:00:00.102,833] <inf> virtual_dai: virtual_dai_probe
[00:00:00.108,476] <inf> dma: sof_dma_get: dir=0, cap=0x0, dev=0x0, flags=0x0
[00:00:00.116,028] <inf> dma: dma_init
[00:00:00.120,198] <inf> dma: sof_dma_get(): Final selection -> ID 0, sref=1, busy=0
[00:00:00.129,043] <inf> ipc: ipc: new cmd 0x80010000
[00:00:00.134,266] <inf> ipc: ipc: dai 16.7 -> config 
[00:00:00.139,820] <inf> virtual_dai: virtual_dai_config_get
[00:00:00.145,896] <inf> virtual_dai: virtual_dai_probe
[00:00:00.151,539] <inf> dai_comp: DAIZ: dai_set_config()
[00:00:00.157,354] <inf> virtual_dai: virtual_dai_config_set
[00:00:00.163,429] <inf> virtual_dai: virtual_dai_remove
[00:00:00.169,163] <inf> ipc: ipc_comp_dai_config() dai type = 16 index = 7
[00:00:00.176,541] <inf> ipc: comp:1.4 dai_config() dai type = 16 index = 7 dd 0x92c05ee0
[00:00:00.185,132] <inf> dai_comp: DAIZ: dai_get_handshake()
[00:00:00.191,208] <inf> virtual_dai: virtual_dai_get_properties

Related Work

SOF PR: #10147 dai: Add support for Virtual DAI for rapid prototyping and software loopback
Adds Virtual DAI support on i.MX8MP with topology and emul_dma integration for software-based audio pipelines.
linux-imx PR: #30 ASoC: SOF: Add Virtual DAI support for i.MX8M
Introduces SOF_DAI_VIRTUAL type and configuration, adds topology tokens, extends IPC3 parsing, and registers a Virtual DAI backend for i.MX8M. Enables prototyping and loopback pipelines without physical DAI hardware.
linux-imx nocodec feature commit: Enabled NoCodec support for the i.MX8M platform to allow pipeline testing without real codecs.
Link: nocodec-commit

Future Work

Implement playback and record:
- Playback: log output frames and discard.
- Record: generate frames filled with zeroes.
  (Current limitation: To get aplay and arecord working, I replaced the real DMA with emul_dma for Virtual DAI. All functions execute, but data is not being copied in dma_emul_work_handler during playback.)

github-actions · 2025-08-31T15:51:16Z

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kv2019i

Thanks @SurajSonawane24 ! Code is looking good. Only some minor notes on documentation, Kconfig defaults and log verbosity. Please see inline.

kv2019i · 2025-09-01T17:27:43Z

drivers/dai/virtual/Kconfig.virtual

+
+config DAI_VIRTUAL
+	bool "Virtual DAI driver support for SOF"
+	default n


"default n" is superfluous -> https://docs.zephyrproject.org/latest/build/kconfig/tips.html#redundant-defaults

Also no need to mention SOF. While SOF is currently the primary user of DAI interface, DAIs could be used by any app.

kv2019i · 2025-09-01T17:28:56Z

drivers/dai/virtual/Kconfig.virtual

+	bool "Virtual DAI driver support for SOF"
+	default n
+	help
+	  Enable support for a Virtual DAI (Digital Audio Interface) in SOF.


Ditto here.

kv2019i · 2025-09-02T07:17:02Z

drivers/dai/virtual/virtual_dai.c

+
+static int virtual_dai_probe(const struct device *dev)
+{
+	LOG_INF("%s", __func__);


I'd reduce the number of these LOG_INF()s in the merged version. I know this virtual DAI is more for R&D use, so logging can be on the more verbose side, but I'd still drop the function entry/exit logs (especially as Zephyr logging can add the function info with a build option, no need to add "func" in driver code.

rruuaanng · 2025-09-02T14:22:55Z

dts/bindings/dai/dai-virtual.yaml

+description: |
+  Zephyr binding for a Virtual DAI (Digital Audio Interface).
+  This DAI is not connected to real hardware and is used for software-only
+  audio routing or testing within SOF + Zephyr systems.


Suggested change

description: |

Zephyr binding for a Virtual DAI (Digital Audio Interface).

This DAI is not connected to real hardware and is used for software-only

audio routing or testing within SOF + Zephyr systems.

title: Zephyr for a Virtual DAI (Digital Audio Interface)

description: |

This DAI is not connected to real hardware and is used for software-only

audio routing or testing within SOF + Zephyr systems.

Thank you for the suggestions, I’ve made the changes.

rruuaanng · 2025-09-02T14:25:31Z

drivers/dai/virtual/virtual_dai.c

+static const struct dai_properties
+	*virtual_dai_get_properties(const struct device *dev, enum dai_dir dir, int stream_id)


Suggested change

static const struct dai_properties

*virtual_dai_get_properties(const struct device *dev, enum dai_dir dir, int stream_id)

static const struct dai_properties *virtual_dai_get_properties(const struct device *dev,

enum dai_dir dir, int stream_id)

or

Suggested change

static const struct dai_properties

*virtual_dai_get_properties(const struct device *dev, enum dai_dir dir, int stream_id)

static const struct dai_properties*

virtual_dai_get_properties(const struct device *dev, enum dai_dir dir, int stream_id)

@rruuaanng I accepted your suggestion, just kept the * with the function name (not the type) to follow kernel coding style.

rruuaanng · 2025-09-02T14:27:56Z

drivers/dai/virtual/virtual_dai.c

+static struct virtual_dai_data virtual_dai_data_##inst = {					\
+	.cfg.type = DAI_VIRTUAL,						\
+	.cfg.dai_index = DT_INST_PROP_OR(inst, dai_index, 0),			\
+};										\
+										\
+DEVICE_DT_INST_DEFINE(inst, \
+		      &virtual_dai_init, NULL, \
+		      &virtual_dai_data_##inst, NULL, \
+		      POST_KERNEL, CONFIG_DAI_INIT_PRIORITY, \
+		      &virtual_dai_api);


Suggested change

static struct virtual_dai_data virtual_dai_data_##inst = { \

.cfg.type = DAI_VIRTUAL, \

.cfg.dai_index = DT_INST_PROP_OR(inst, dai_index, 0), \

}; \

\

DEVICE_DT_INST_DEFINE(inst, \

&virtual_dai_init, NULL, \

&virtual_dai_data_##inst, NULL, \

POST_KERNEL, CONFIG_DAI_INIT_PRIORITY, \

&virtual_dai_api);

static struct virtual_dai_data virtual_dai_data_##inst = { \

.cfg.type = DAI_VIRTUAL, \

.cfg.dai_index = DT_INST_PROP_OR(inst, dai_index, 0), \

}; \

\

DEVICE_DT_INST_DEFINE(inst, \

&virtual_dai_init, NULL, \

&virtual_dai_data_##inst, NULL, \

POST_KERNEL, CONFIG_DAI_INIT_PRIORITY, \

&virtual_dai_api);

@rruuaanng Thanks for the suggestion. Can you clarify the reason for these whitespace changes?

SurajSonawane2415 · 2025-09-03T05:22:37Z

Thanks @SurajSonawane24 ! Code is looking good. Only some minor notes on documentation, Kconfig defaults and log verbosity. Please see inline.

@kv2019i Thanks for the detailed review!

Dropped the redundant default n.
Removed “SOF” mention from Kconfig description.
Cleaned up logging by dropping function entry/exit logs, keeping only meaningful ones (using DBG instead of INF).

kv2019i

Thanks, looks good now @SurajSonawane2415 !

LaurentiuM1234

Good start, but IMO this should still be in the draft stage. I would like to see some actual functionality being implemented here. IMO, as things stand now, this PR introduces a DAI driver that doesn't seem to do anything and a test suite that doesn't test anything particularly useful?

LaurentiuM1234 · 2025-09-03T17:25:15Z

dts/bindings/dai/dai-virtual.yaml

+  Zephyr binding for a Virtual DAI (Digital Audio Interface).
+  This DAI is not connected to real hardware and is used for software-only
+  audio routing or testing within SOF + Zephyr systems.
+compatible: "virtual_dai"


The format of the compatible string is "vendor,model". Also, should be virtual-dai. My suggestion would be to use zephyr,virtual-dai.

Thank you I will make the changes.

LaurentiuM1234 · 2025-09-03T17:29:38Z

dts/xtensa/nxp/nxp_imx8m.dtsi

 			status = "disabled";
 		};

+		virtual_dai: virtual_dai {


no virtual devices in the mainline DT, please. We can move this to the application DT overlay. See host_dma from https://github.com/thesofproject/sof/blob/main/app/boards/imx8qm_mek_mimx8qm6_adsp.overlay as an example.

Got it, thanks for pointing this out. I’ve removed it.
I’ll refer to the host_dma example you shared for guidance.

SurajSonawane2415 · 2025-09-04T09:05:25Z

Good start, but IMO this should still be in the draft stage. I would like to see some actual functionality being implemented here. IMO, as things stand now, this PR introduces a DAI driver that doesn't seem to do anything and a test suite that doesn't test anything particularly useful?

Thanks for the feedback! I’ve marked it as draft.

Introduce a virtual DAI driver for prototyping, loopback, and testing without requiring physical DAI hardware. This includes: - Initial virtual DAI implementation (logging only) - DTS binding (dai-virtual.yaml) - Kconfig and CMake updates - i.MX8M DTS integration Signed-off-by: Suraj Sonawane <[email protected]>

Add a basic ztest-based testsuite for the virtual DAI driver. This includes initial API coverage and simple validation. Signed-off-by: Suraj Sonawane <[email protected]>

sonarqubecloud · 2025-09-08T15:52:34Z

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

zephyrbot added area: Devicetree area: Xtensa Xtensa Architecture area: DAI labels Aug 31, 2025

zephyrbot requested review from LaurentiuM1234, andyross, ceolin, dbaluta, dcpleung, decsny, galak, iuliana-prodan, juimonen, kv2019i, lgirdwood, mbolivar, nashif and rruuaanng August 31, 2025 15:51

zephyrbot assigned kv2019i and LaurentiuM1234 Aug 31, 2025

SurajSonawane2415 mentioned this pull request Aug 31, 2025

dai: Add support for Virtual DAI for rapid prototyping and software loopback thesofproject/sof#10147

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SurajSonawane2415 force-pushed the feature/zephyr-virtual-dai branch from 9fe555a to f25130f Compare August 31, 2025 16:01

SurajSonawane2415 mentioned this pull request Sep 1, 2025

ASoC: SOF: Add Virtual DAI support for i.MX8M nxp-imx/linux-imx#30

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SurajSonawane2415 force-pushed the feature/zephyr-virtual-dai branch from f25130f to 7dfac22 Compare September 2, 2025 07:00

kv2019i requested changes Sep 2, 2025

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SurajSonawane2415 force-pushed the feature/zephyr-virtual-dai branch from 7dfac22 to 7f3747d Compare September 3, 2025 05:22

kv2019i previously approved these changes Sep 3, 2025

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SurajSonawane2415 dismissed kv2019i’s stale review via 7cc9c25 September 4, 2025 05:37

SurajSonawane2415 force-pushed the feature/zephyr-virtual-dai branch from 7f3747d to 7cc9c25 Compare September 4, 2025 05:37

SurajSonawane2415 marked this pull request as draft September 4, 2025 09:02

SurajSonawane2415 added 2 commits September 8, 2025 20:50

tests: drivers: dai: Add tests for virtual DAI

a6c0c23

Add a basic ztest-based testsuite for the virtual DAI driver. This includes initial API coverage and simple validation. Signed-off-by: Suraj Sonawane <[email protected]>

SurajSonawane2415 force-pushed the feature/zephyr-virtual-dai branch from 7cc9c25 to a6c0c23 Compare September 8, 2025 15:26

		static const struct dai_properties
		virtual_dai_get_properties(const struct device dev, enum dai_dir dir, int stream_id)

drivers: dai: Add virtual DAI driver and tests #95233

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drivers: dai: Add virtual DAI driver and tests #95233

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SurajSonawane2415 commented Aug 31, 2025 •

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