Hi Mark
commit 25612477d20b52 ("ASoC: soc-dai: set dai_link dpcm_ flags with a helper") added snd_soc_dai_link_set_capabilities(). But it is using snd_soc_find_dai() (A) which is required client_mutex (B). And client_mutex is soc-core.c local.
struct snd_soc_dai *snd_soc_find_dai(xxx) { ... (B) lockdep_assert_held(&client_mutex); ... }
void snd_soc_dai_link_set_capabilities(xxx) { ... for_each_pcm_streams(direction) { ... for_each_link_cpus(dai_link, i, cpu) { (A) dai = snd_soc_find_dai(cpu); ... } ... for_each_link_codecs(dai_link, i, codec) { (A) dai = snd_soc_find_dai(codec); ... } } ... }
Because of these background, we will get WARNING if .config has CONFIG_LOCKDEP.
WARNING: CPU: 2 PID: 53 at sound/soc/soc-core.c:814 snd_soc_find_dai+0xf8/0x100 CPU: 2 PID: 53 Comm: kworker/2:1 Not tainted 5.7.0-rc1+ #328 Hardware name: Renesas H3ULCB Kingfisher board based on r8a77951 (DT) Workqueue: events deferred_probe_work_func pstate: 60000005 (nZCv daif -PAN -UAO) pc : snd_soc_find_dai+0xf8/0x100 lr : snd_soc_find_dai+0xf4/0x100 ... Call trace: snd_soc_find_dai+0xf8/0x100 snd_soc_dai_link_set_capabilities+0xa0/0x16c graph_dai_link_of_dpcm+0x390/0x3c0 graph_for_each_link+0x134/0x200 graph_probe+0x144/0x230 platform_drv_probe+0x5c/0xb0 really_probe+0xe4/0x430 driver_probe_device+0x60/0xf4
Many drivers are already calling snd_soc_find_dai() and/or snd_soc_dai_link_set_capabilities(). Thus, same thing can be happen on these drivers, too.
grep snd_soc_find_dai -rl sound/soc/*
sound/soc/samsung/tm2_wm5110.c sound/soc/soc-core.c sound/soc/soc-dai.c sound/soc/soc-topology.c sound/soc/sof/topology.c
grep snd_soc_dai_link_set_capabilities -rl sound/soc/*
sound/soc/generic/simple-card.c sound/soc/generic/audio-graph-card.c sound/soc/qcom/common.c sound/soc/soc-dai.c
I noticed that samsung / sof are using snd_soc_find_dai() under client_mutex. This means this patch creates deadlock for these. Hmm... we need both _with_mutex() and _without_mutex().
Thank you for your help !!
Best regards --- Kuninori Morimoto