[alsa-devel] LSI HDA Modem is not working on HP new Laptop which has IDT 7605 HDA codec and REDHAT installed on it with ALSA ver 1.0.24.

[Takashi Iwai]

At Tue, 11 Oct 2011 14:49:00 +0530,
suresh gupta wrote:
> 
> Our modem works with this fix, so I try to understand it and found that, the
> only difference is now "azx_assign_device" function assign stream from last
> position and assign last one.  This is the reason why our modem works with
> this fix as our modem try to get stream from first position and get first
> one.
> 
> Do you really want this to do and what the significance of acquiring stream
> from last position?

Not really much.  The only goal is to re-use the last used stream
at the next open.


Takashi

> However from your previous explanation about new logic, I fixed the issue by
> making change in our modem code.
> Thanks for your support and help.
> SuresH
> 
> On Thu, Oct 6, 2011 at 1:54 PM, Takashi Iwai <tiwai at suse.de> wrote:
> 
> > At Thu, 29 Sep 2011 10:46:02 +0200,
> > Takashi Iwai wrote:
> > >
> > > At Thu, 29 Sep 2011 14:01:40 +0530,
> > > suresh gupta wrote:
> > > >
> > > > Sorry for delay, I was out for Lunch.
> > > >
> > > > I believe we are in sink now, I seen the purity_inactive_streams part
> > of
> > > > code and found this is totally new logic in 1.0.24 ver. Can you please
> > > > answer some question for my proper understanding?
> > > >
> > > > 1. Why this marking stream dirty come into picture and why ALSA code do
> > not
> > > > directly clear the AC_VERB_SET_CHANNEL_STREAMID while closing?
> > >
> > > For keeping the same stream tag for the same device.
> > > A device is often shortly closed and reopened.  It'd be better to keep
> > > the same stream tag for such a case.
> >
> > While reading the code again, it seems that the code in hda_intel.c
> > doesn't do perfectly for some stream setups.  For example, it blindly
> > relies on pcm->device number, so playback and capture streams won't be
> > distinguished, and the first taker will win always.
> >
> > I fixed it now with the patch below.
> >
> >
> > Takashi
> >
> > ===
> > From: Takashi Iwai <tiwai at suse.de>
> > Subject: ALSA: hda - Distinguish each substream for better sticky
> > assignment
> >
> > The commit ef18beded8ddbaafdf4914bab209f77e60ae3a18 introduced a
> > mechanism to assign the previously used slot for the next reopen of a
> > PCM stream.  But the PCM device number isn't always unique (it may
> > have multiple substreams), and also the code doesn't check the stream
> > direction, thus both playback and capture streams share the same
> > device number.
> >
> > For avoiding this conflict, make a unique key for each substream and
> > store/check this value at reopening.
> >
> > Signed-off-by: Takashi Iwai <tiwai at suse.de>
> > ---
> >  sound/pci/hda/hda_intel.c |    9 ++++++---
> >  1 files changed, 6 insertions(+), 3 deletions(-)
> >
> > diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
> > index 8a5dc57..90713f0 100644
> > --- a/sound/pci/hda/hda_intel.c
> > +++ b/sound/pci/hda/hda_intel.c
> > @@ -381,7 +381,7 @@ struct azx_dev {
> >                                         */
> >        unsigned char stream_tag;       /* assigned stream */
> >        unsigned char index;            /* stream index */
> > -       int device;                     /* last device number assigned to
> > */
> > +       int assigned_key;               /* last device# key assigned to */
> >
> >        unsigned int opened :1;
> >        unsigned int running :1;
> > @@ -1613,6 +1613,9 @@ azx_assign_device(struct azx *chip, struct
> > snd_pcm_substream *substream)
> >  {
> >        int dev, i, nums;
> >        struct azx_dev *res = NULL;
> > +       /* make a non-zero unique key for the substream */
> > +       int key = (substream->pcm->device << 16) | (substream->number << 2)
> > |
> > +               (substream->stream + 1);
> >
> >        if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
> >                dev = chip->playback_index_offset;
> > @@ -1624,12 +1627,12 @@ azx_assign_device(struct azx *chip, struct
> > snd_pcm_substream *substream)
> >        for (i = 0; i < nums; i++, dev++)
> >                if (!chip->azx_dev[dev].opened) {
> >                        res = &chip->azx_dev[dev];
> > -                       if (res->device == substream->pcm->device)
> > +                       if (res->assigned_key == key)
> >                                break;
> >                }
> >        if (res) {
> >                res->opened = 1;
> > -               res->device = substream->pcm->device;
> > +               res->assigned_key = key;
> >        }
> >        return res;
> >  }
> > --
> > 1.7.7
> >
> >