[ursus161]

SND_SOC_SOF_DEBUG_PROBES was not selectable for i.MX and no auxiliary probes client device was registered.

Add a hidden Kconfig symbol SND_SOC_SOF_IMX_PROBES (selected by SND_SOC_SOF_IMX8 when DEBUG_FS is on), a new imx-probes.c that registers the client, allocates a coherent DMA buffer and passes its bus address to the firmware in PROBE_INIT stream_tag. A 10 ms delayed work polls the DSP write counter, copies new data into the compress buffer and calls snd_compr_fragment_elapsed().

Known limits: polling only, single stream, 32-bit DMA address.

[sofci]

Can one of the admins verify this patch?

reply test this please to run this test once

[ursus161]

Hi all,

Tested this on a imx8mp-evk : 1kHz tone at 48 kHz stereo, captured via probes, decodes fine.

I am not so sure about these, please provide feedback :

1. The address handoff : extractor_stream_tag = (u32)s->paddr in imx_probes_compr_set_params() . Would a dedicated field in the probe init payload be better?
2. About static struct imx_probes_stream imx_stream; : Every callback reads and writes that same object. That works for one recording at a time. It may break if someone opens a second recording or reloads the module, because the old state isn't tied to the stream that created it. The fix is to store the state per stream, the way the HDA client does, so each recording owns its own copy and frees it on shutdown. Would it work better?
3. 10ms polling timer schedule_delayed_work(&s->work, msecs_to_jiffies(IMX_PROBES_POLL_MS)); . Should I change this into a notification path?

Happy to change commit these changes.

@dbaluta @plbossart @plbossart @bardliao @sofci

[Copilot]

🟡 Changes recommended

Uninitialized work cancellation and concurrent opens can trigger kernel panics or free an active DMA buffer, while incorrect buffer and restart accounting can expose stale or corrupted audio data.

5 open issues

• Reject concurrent opens that share the singleton stream · New
• Initialize work item before cleanup can cancel it · New
• Keep DSP consumption and ALSA produced-byte counts separate · New
• Prevent overwriting unread data in the compress buffer · New
• Reset ALSA byte accounting when restarting after STOP · New

What changed in this PR

Adds an IPC3 probe-extraction client for i.MX8, connecting the platform to the existing SOF probes infrastructure.

Changes:

• Enables the probes client through Kconfig and build integration.
• Adds a coherent DMA ring buffer with 10 ms polling to deliver DSP data to the compress buffer.
• Registers the i.MX probes auxiliary device and its lifecycle callbacks.

File	Description
sound/​soc/​sof/​sof-client-probes.c	Adds the i.MX auxiliary-device match.
sound/​soc/​sof/​imx/​Makefile	Includes the probes implementation in the i.MX8 build.
sound/​soc/​sof/​imx/​Kconfig	Selects probes support for i.MX8 when debugfs is enabled.
sound/​soc/​sof/​imx/​imx8.c	Hooks probes registration and unregistration into platform operations.
sound/​soc/​sof/​imx/​imx-probes.c	Implements DMA allocation, polling, and compress-stream callbacks.
sound/​soc/​sof/​imx/​imx-common.h	Declares the probes registration helpers.

_{Review effort: Balanced}

[dbaluta]

Do we want to have SND_SOC_SOF_IMX_PROBES enabled all the time for IMX? I wonder how Intel is doing?

[dbaluta]

Here only the SPDX and copyright should use // comments style. The rest should use C classic comments style /* ... */.

[ursus161]

Do we want to have SND_SOC_SOF_IMX_PROBES enabled all the time for IMX? I wonder how Intel is doing?

Mostly the same,

In the Intel side of things, at sound/soc/sof/intel/Kconfig:324 SND_SOC_SOF_HDA_GENERIC selects SND_SOC_SOF_HDA_PROBES with no regard to DEBUG_FS condition.

Here, SND_SOC_SOF_IMX_PROBES is hidden. SND_SOC_SOF_IMX8 selects it if DEBUG_FS.

[ursus161]

Do we want to have SND_SOC_SOF_IMX_PROBES enabled all the time for IMX? I wonder how Intel is doing?

Mostly the same,

In the Intel side of things, at sound/soc/sof/intel/Kconfig:324 SND_SOC_SOF_HDA_GENERIC selects SND_SOC_SOF_HDA_PROBES with no regard to DEBUG_FS condition.

Here, SND_SOC_SOF_IMX_PROBES is hidden. SND_SOC_SOF_IMX8 selects it if DEBUG_FS.

At second thought, we can enable the SND_SOC_SOF_IMX_PROBES without any condition, to be aligned with Intel. Will push changes soon.