Re: [PATCH] ALSA: aoa: Handle empty codec list in i2sbus_pcm_prepare()

[Thorsten Blum <thorsten.blum@linux.dev>]

On 9. Mar 2026, at 12:59, Takashi Iwai wrote:
> On Mon, 09 Mar 2026 12:41:59 +0100, Thorsten Blum wrote:
>> Replace two list_for_each_entry() loops with list_first_entry_or_null()
>> in i2sbus_pcm_prepare().
> 
> Hmm, I guess both can be simply list_first_entry(), as the codec list
> in this code path is guaranteed to be non-empty (it's called after
> i2sbus_pcm_open() which has the check of the valid codecs).

That guarantee only holds for open/prepare, not for i2sbus_resume() via
i2sbus_pcm_prepare_both(). It's probably uncommon in practice, but
i2sbus_pcm_prepare() should still handle it safely.

>> Handle an empty codec list explicitly by returning -ENODEV, which avoids
>> using uninitialized 'bi.sysclock_factor' in the 32-bit code path.
> 
> Which 32bit code path are you referring to...?

The SNDRV_PCM_FORMAT_S32_BE/SNDRV_PCM_FORMAT_U32_BE branch.

Thanks,
Thorsten