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CC:     <spujar@nvidia.com>, <broonie@kernel.org>,
        <alsa-devel@alsa-project.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [RFC] ASoC: soc-pcm: crash in snd_soc_dapm_new_dai
To:     <tiwai@suse.com>, <perex@perex.cz>
References: <1579443563-12287-1-git-send-email-spujar@nvidia.com>
From:   Sameer Pujar <spujar@nvidia.com>
Message-ID: <32021032-6b3c-9056-d194-ce7902e5fcbf@nvidia.com>
Date:   Thu, 23 Jan 2020 15:25:06 +0530
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Hi All,
Request for comments if my understanding is right here. Thanks.

On 1/19/2020 7:49 PM, Sameer Pujar wrote:
> Crash happens in snd_soc_dapm_new_dai() when substream->private_data
> access is made and substream is NULL here. This is seen for DAIs where
> only playback or capture stream is defined. This seems to be happening
> for codec2codec DAI link.
>
> Both playback and capture are 0 during soc_new_pcm(). This is probably
> happening because cpu_dai and codec_dai are both validated either for
> SNDRV_PCM_STREAM_PLAYBACK or SNDRV_PCM_STREAM_CAPTURE.
>
> Shouldn't be playback = 1 when,
>   - playback stream is available for codec_dai AND
>   - capture stream is available for cpu_dai
>
> and vice-versa for capture = 1?
>
> Signed-off-by: Sameer Pujar <spujar@nvidia.com>
> ---
>   sound/soc/soc-pcm.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/sound/soc/soc-pcm.c b/sound/soc/soc-pcm.c
> index 74d340d..5aa9c0b 100644
> --- a/sound/soc/soc-pcm.c
> +++ b/sound/soc/soc-pcm.c
> @@ -2855,10 +2855,10 @@ int soc_new_pcm(struct snd_soc_pcm_runtime *rtd, int num)
>   
>   		for_each_rtd_codec_dai(rtd, i, codec_dai) {
>   			if (snd_soc_dai_stream_valid(codec_dai, SNDRV_PCM_STREAM_PLAYBACK) &&
> -			    snd_soc_dai_stream_valid(cpu_dai,   SNDRV_PCM_STREAM_PLAYBACK))
> +			    snd_soc_dai_stream_valid(cpu_dai,   SNDRV_PCM_STREAM_CAPTURE))
>   				playback = 1;
>   			if (snd_soc_dai_stream_valid(codec_dai, SNDRV_PCM_STREAM_CAPTURE) &&
> -			    snd_soc_dai_stream_valid(cpu_dai,   SNDRV_PCM_STREAM_CAPTURE))
> +			    snd_soc_dai_stream_valid(cpu_dai,   SNDRV_PCM_STREAM_PLAYBACK))
>   				capture = 1;
>   		}
>