[alsa-devel] [PATCH] ALSA: hda - Fix a wrong busy check in alt PCM open

[Raymond Yau]

>
> Currently, the alt PCM open callback returns -EBUSY when an
> independent HP is turned off, supposing that it conflicts with the
> main PCM.  However, obviously, this check is wrong when the
> independent HP itself isn't enabled but the alt PCM was explicitly
> created via alc_dac_nid by a codec driver.

The alt_pcm is created only when indep_hp == 1

When indep_hp_enable = 0, HP is reconnected to analog device stream , alt
analog device return ebusy

This look like bug in indep_hp_possible() which should return false when HP
and Line Out/Speaker share same DAC

There are exception even when HP and Line Out are assigned different DACs
(e.g. those 6 channels HDA codecs ad1986a and alc66x does not support
multistreaming)