Re: [PATCH v2 3/9] ASoC: audio-graph: Identify 'no_pcm' DAI links for DPCM

From: Sameer Pujar <spujar@nvidia.com>
To: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Cc: jonathanh@nvidia.com, nicoleotsuka@gmail.com,
	alsa-devel@alsa-project.org, atalambedu@nvidia.com,
	swarren@nvidia.com, linux-kernel@vger.kernel.org,
	nwartikar@nvidia.com, lgirdwood@gmail.com, robh+dt@kernel.org,
	tiwai@suse.com, viswanathl@nvidia.com, sharadg@nvidia.com,
	broonie@kernel.org, thierry.reding@gmail.com,
	linux-tegra@vger.kernel.org, rlokhande@nvidia.com,
	mkumard@nvidia.com, dramesh@nvidia.com
Subject: Re: [PATCH v2 3/9] ASoC: audio-graph: Identify 'no_pcm' DAI links for DPCM
Date: Tue, 25 Aug 2020 08:55:56 +0530	[thread overview]
Message-ID: <2d3aa11e-3c56-1f7a-3d41-2457f973d55b@nvidia.com> (raw)
In-Reply-To: <97f325a6-96cc-11c5-8027-8c0a159e3da0@nvidia.com>

Hi Morimoto-san,

>> (snip)
>>> +static bool soc_component_is_pcm(struct snd_soc_dai_link_component 
>>> *dlc)
>>> +{
>>> +     struct snd_soc_dai *dai = snd_soc_find_dai(dlc);
>>> +
>>> +     if (dai && (dai->component->driver->pcm_construct ||
>>> +                 dai->driver->pcm_new))
>>> +             return true;
>>> +
>>> +     return false;
>>> +}
>> This snd_soc_find_dai() will indicate WARNING
>> if .config has CONFIG_LOCKDEP for me.
>>
>> Maybe implement it at soc-core.c with client_mutex lock
>> is needed.

I tried testing this with LOCKDEP config enabled at my end. It seems I 
don't see warning originated from above function. Are you suggesting 
that, in general, snd_soc_find_dai() should be called with client_mutex 
held?

However I do see below warning and stack which is not related to above 
function call.
   dump_backtrace+0x0/0x1c0
   show_stack+0x18/0x28
   dump_stack+0xc8/0x128
   __warn+0xa0/0x15c
   report_bug+0xc8/0x180
   bug_handler+0x20/0x80
   brk_handler+0x6c/0xc0
   do_debug_exception+0xd8/0x1f0
   el1_sync_handler+0x98/0x128
   el1_sync+0x7c/0x100
   snd_soc_find_dai+0x10c/0x120 [snd_soc_core]
   snd_soc_dai_link_set_capabilities+0xc0/0x168 [snd_soc_core]
   graph_dai_link_of_dpcm+0x3a4/0x410 [snd_soc_audio_graph_card]
   graph_for_each_link+0x174/0x220 [snd_soc_audio_graph_card]
   graph_probe+0x174/0x270 [snd_soc_audio_graph_card]

May be *snd_soc_dai_link_set_capabilities**()* requires similar fix?

Thanks,
Sameer