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

SurajSonawane2415 · 2025-07-31T17:20:52Z

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 SOF_DAI_VIRTUAL type and 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.

Virtual DAI Behavior

Playback: Acts like /dev/null — consumes data from the source and logs or discards it.
Capture: Acts like /dev/zero — generates dummy data (currently zero-filled) and passes it to the sink.

Key Changes

Added Virtual DAI support on i.MX8MP
- Added a new DAI type SOF_DAI_VIRTUAL for rapid prototyping and software loopback.
- Defined IPC config structure and updated Zephyr DAI mapping for Virtual DAI recognition.
- Enabled software-based audio pipelines without requiring physical DAI hardware.
Topology support for i.MX8
- Introduced a new topology file enabling Virtual DAI on i.MX8 platforms.
DMA configuration update
- Integrated emul_dma to enable Virtual DAI functionality on i.MX8MP.
- Allows playback/record flows in the absence of real hardware DMA.

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 PR & Commits

Zephyr PR: #95233 drivers: dai: Add virtual DAI driver and tests
Includes Virtual DAI driver, DTS binding, Kconfig/CMake updates, and ztest-based API tests.
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.)

sofci · 2025-07-31T17:24:38Z

Can one of the admins verify this patch?

reply test this please to run this test once

lyakh · 2025-08-01T08:02:11Z

src/include/ipc/dai.h

 	SOF_DAI_IMX_MICFIL,		/**< i.MX MICFIL */
-	SOF_DAI_AMD_SW_AUDIO		/**<Amd SW AUDIO */
+	SOF_DAI_AMD_SW_AUDIO,		/**<Amd SW AUDIO */
+	SOF_DAI_VIRTUAL			/**< Virtual DAI for testing/debugging*/


can we add a comma at the end to prepare for the next addition?

@SurajSonawane2415 please add comma after last member e.g SOF_DAI_VIRTUAL,

lyakh · 2025-08-01T08:04:23Z

src/lib/dai.c

 		d->dma_caps = SOF_DMA_CAP_HDA;
 		break;
+	case SOF_DAI_VIRTUAL:
+		break;


already handled by default below

zephyr/include/sof/lib/dma.h

iuliana-prodan · 2025-08-01T08:59:19Z

tools/topology/topology1/sof-imx8-virtual.m4

+
+# Low Latency playback pipeline 1 on PCM 0 using max 2 channels of s24le
+PIPELINE_PCM_ADD(sof/pipe-volume-playback.m4,
+	1, 0, 2, s24le,


why s24le? it should be s32le.

iuliana-prodan · 2025-08-01T09:03:39Z

tools/topology/topology1/sof-imx8-virtual.m4

@@ -0,0 +1,72 @@
+


This topology seems to be quite generic, not specific to 8MP.
@dbaluta maybe you can test this on 8QM or 8QXP so we can be sure it works on other platforms as well.

@SurajSonawane2415 since this is virtual it may be possible to create a ztest for this feature (in another PR), this would mean the feature would be tested by CI. i.e. a small pipeline with virtual loopback as a ztest.

@lgirdwood something like this zephyr/tests/drivers/i2s/i2s_api/src/test_i2s_loopback.c but for DAI, right?

Fwiw, this would allow a higher level ztest where we could have a small loopback pipeline and test that we can copy A -> B, this would invoke a lot of pipeline logic/infra and could be easily run in CI. Depends if time permits for development though.

lgirdwood

LGTM

dbaluta · 2025-08-21T13:44:00Z

app/boards/imx8mp_evk_mimx8ml8_adsp.overlay

 		compatible = "nxp,sof-host-dma";
 		dma-channels = <32>;
 		#dma-cells = <0>;
 	};


@SurajSonawane2415 we should not enable DAI_VIRTUAL and DMA_EMUL by default so please remove them from the config file.

dbaluta · 2025-08-21T14:02:43Z

zephyr/lib/dma.c

+	},
+	.z_dev = DEVICE_DT_GET(DT_NODELABEL(emul_dma)),
+},
+#else


Here you should just add #endif.

src/lib/dai.c

dbaluta · 2025-08-22T13:42:27Z

tools/topology/topology1/sof/tokens.m4

+
+SectionVendorTokens."sof_virtual_tokens" {
+	SOF_TKN_DAI_VIRTUAL_MCLK_ID		"2102"
+}


I think this should be SOF_TKN_DAI_VIRTUAL_MCLK_ID 22000 to allow sufficient space between members.

@SurajSonawane2415 can you add the same token ID to topology 2 tokens too, just to make sure we have alignment.

lgirdwood · 2025-08-25T16:09:10Z

tools/topology/topology1/sof/tokens.m4

+
+SectionVendorTokens."sof_virtual_tokens" {
+	SOF_TKN_DAI_VIRTUAL_MCLK_ID		"2102"
+}


@SurajSonawane2415 can you add the same token ID to topology 2 tokens too, just to make sure we have alignment.

lgirdwood · 2025-08-25T16:11:17Z

src/audio/dai-zephyr.c

+#if CONFIG_DAI_VIRTUAL
+	dir = SOF_DMA_DIR_MEM_TO_MEM;
+#else


Is there anyway we can do this without the ifdef i.e. we may want to be able to combine virtual and real DAIs, you could add a flag to the dai structure to indicate virtual ?

Introduce a new DAI type, SOF_DAI_VIRTUAL, to enable rapid prototyping, software loopback, and testing without requiring physical DAI hardware. Define the IPC config structure for the virtual DAI and update the Zephyr DAI mapping logic to recognize and configure this backend. Enable virtual DAI for i.MX8MP to support software-based audio pipelines. Signed-off-by: Suraj Sonawane <surajsonawane0215@gmail.com>

Add a new topology file for i.MX8 platforms that enables Virtual DAI support, allowing software-based audio pipelines without physical DAI hardware. Signed-off-by: Suraj Sonawane <surajsonawane0215@gmail.com>

Add emul_dma configuration to enable Virtual DAI with memory-to-memory DMA for software-based audio pipelines on i.MX8MP. Signed-off-by: Suraj Sonawane <surajsonawane0215@gmail.com>

SurajSonawane2415 requested review from RanderWang, abonislawski, dbaluta, iuliana-prodan, kv2019i, lbetlej, lgirdwood, lyakh, marcinszkudlinski, mmaka1, pblaszko, plbossart and ranj063 as code owners July 31, 2025 17:20

SurajSonawane2415 marked this pull request as draft July 31, 2025 17:21

SurajSonawane2415 force-pushed the feature/virtual-dai-support branch from 86aa27b to 7168fe9 Compare July 31, 2025 19:31

lyakh reviewed Aug 1, 2025

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SurajSonawane2415 force-pushed the feature/virtual-dai-support branch 2 times, most recently from 3b19886 to 9a09895 Compare August 4, 2025 02:22

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dbaluta reviewed Aug 21, 2025

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zephyr/lib/dma.c Outdated

},

.z_dev = DEVICE_DT_GET(DT_NODELABEL(emul_dma)),

},

#else

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dbaluta Aug 21, 2025

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Here you should just add #endif.

SurajSonawane2415 force-pushed the feature/virtual-dai-support branch 3 times, most recently from bc0bb10 to 2db9df2 Compare August 22, 2025 10:05

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SurajSonawane2415 force-pushed the feature/virtual-dai-support branch from 2db9df2 to 52b5f8c Compare August 25, 2025 04:52

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SurajSonawane2415 force-pushed the feature/virtual-dai-support branch from 52b5f8c to 9441b0c Compare August 27, 2025 05:50

SurajSonawane2415 added 2 commits August 27, 2025 11:38

topology1: Add support for Virtual DAI for i.MX8

67398e1

Add a new topology file for i.MX8 platforms that enables Virtual DAI support, allowing software-based audio pipelines without physical DAI hardware. Signed-off-by: Suraj Sonawane <surajsonawane0215@gmail.com>

zephyr: Use emul_dma for Virtual DAI on i.MX8MP

dace206

Add emul_dma configuration to enable Virtual DAI with memory-to-memory DMA for software-based audio pipelines on i.MX8MP. Signed-off-by: Suraj Sonawane <surajsonawane0215@gmail.com>

SurajSonawane2415 force-pushed the feature/virtual-dai-support branch from 9441b0c to dace206 Compare August 27, 2025 06:09

SurajSonawane2415 changed the title ~~[RFC] dai: Add support for Virtual DAI for rapid prototyping and software loopback~~ dai: Add support for Virtual DAI for rapid prototyping and software loopback Aug 31, 2025

This was referenced Aug 31, 2025

drivers: dai: Add virtual DAI driver and tests zephyrproject-rtos/zephyr#95233

Closed

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

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

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Virtual DAI Behavior

Key Changes

Testing

Related PR & Commits

Future Work

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SurajSonawane2415 commented Jul 31, 2025 •

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