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IPC4 delay reporting is not working if DSP pipelne has a SRC/resampler #5498
Description
When DSP pipelines have a SRC (like the SOF nocodec topology since commit 2a7a94d238a117946acc25607ad0978ea4923d9e by @singalsu ), the IPC4 delay reporting is not working correctly in SOF Linux driver.
This was originally discovered by runnign alsa_conformance_test on SOF nocodec topology's PCM2 (that has the SRCs).
Alternatively, observing the PCM runtime status during e.g.
aplay -Dhw:0,2 -r 96000 -c 2 -f s16_le -traw /dev/zero -vv
... shows PCM delay to continuously increase.
Tested with SOF FW and Linux of 2025-07-30.
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kv2019i commentedon Jul 30, 2025
With current sof-dev mainline kernel+FW, running conformance test on sofnocodec,2 (the one with the SRCs in DSP pipeline)
$ alsa_conformance_test.py -P hw:sofnocodec,2 --avail-delay
gives lots of errors like this:
INFO:root:Execute command: alsa_conformance_test -P hw:sofnocodec,2 -d 1 -r 8000 -B 40 -c 2 -f S16_LE -p 40 --avail-delay
INFO:root:Set rate 8000
INFO:root:fail - Expected rate is 8000, measure 8.443636901867766e+16, difference 8.443636901866966e+16 > threshold 0.8
INFO:root:Execute command: alsa_conformance_test -P hw:sofnocodec,2 -d 1 -r 11025 -B 55 -c 2 -f S16_LE -p 55 --avail-delay
INFO:root:Set rate 11025
INFO:root:fail - Expected rate is 11025, measure 1.689902907257662e+17, difference 1.6899029072575517e+17 > threshold 1.1025
INFO:root:Execute command: alsa_conformance_test -P hw:sofnocodec,2 -d 1 -r 16000 -B 80 -c 2 -f S16_LE -p 80 --avail-delay
INFO:root:Set rate 16000
INFO:root:fail - Expected rate is 16000, measure 2.5280888746798378e+17, difference 2.5280888746796778e+17 > threshold 1.6
INFO:root:Execute command: alsa_conformance_test -P hw:sofnocodec,2 -d 1 -r 22050 -B 110 -c 2 -f S16_LE -p 110 --avail-delay
With overall results:
"21 passed, 44 failed"
With #5499 , same test now passes all but one case. There is still an issue with the estimated playback position (estimated = combining pcm_avail with the reported PCM delay ) goes backwards by a few frames at times. This seems to only happen with the SRC pipelines, but I've not been able to rootcause this yet and thus #5499 is still as a draft.
kv2019i commentedon Aug 28, 2025
Closed via #5499