The issue was that we were seeing a memory corruption bug on an AMD chromebooks with that function already (not observed on Intel). I was testing some SOF integrations and was seeing this in the kernel logs. I had Dylan verify my logic before I sent the patch because it took so long to identify the bug and it was traced to the patch that introduce soc_init_platform.
[ 10.922112] cz-da7219-max98357a AMD7219:00: ASoC: CPU DAI designware-i2s.1.auto not registered [ 10.922122] cz-da7219-max98357a AMD7219:00: devm_snd_soc_register_card(acpd7219m98357) failed: -517 [ 11.001411] cz-da7219-max98357a AMD7219:00: ASoC: Both platform name/of_node are set for amd-max98357-play [ 11.001423] cz-da7219-max98357a AMD7219:00: ASoC: failed to init link amd-max98357-play [ 11.001431] cz-da7219-max98357a AMD7219:00: devm_snd_soc_register_card(acpd7219m98357) failed: -22 [ 11.001577] cz-da7219-max98357a: probe of AMD7219:00 failed with error -22
of_node was never getting set but the pointer was becoming populated (outside of the probe call) which traced to soc_init_platform function which was not reallocating memory on a EPROBE_DEFER even though it was getting freed by devm. I am not very familiar with devm but my local maintainers say that it should be freeing the memory even on a PROBE_DEFER. The patch should mirror the memory behaviour in snd_soc_init_multicodec which also reallocates its memory on every probe. I'm not sure how the patch is causing you to defer, is your component list corrupt?
Sorry for the duplicate spam, forgot to send via plain text mode, re-sending for the mailing list so it gets accepted.
There is no defer issue with the intel stuff, but we call this routine multiple times
snd_soc_register_card
--soc_init_dai_link
----snd_soc_init_platform
-- soc_soc_bind_card
----snd_soc_instantiate_card
------ soc_check_tplg_fes
-------- snd_soc_init_platform << ALLOC1
--------soc_init_dai_link
----------snd_soc_init_platform << ALLOC2
Initially dai_link->legacy_platform is 0, so gets set after the first first devm_kzalloc (ALLOC1) and after that we always allocate new memory (ALLOC2). The end result is that whatever we set in soc_check_tplg_fes is lost with the new/unnecessary alloc.
I would guess your solution is also a work-around, if devm_ effectively freed the memory then the pointer would become NULL. Or may that's the issue is that no one actually resets it.