Re: Maintaining sound card at a specific frequency

[Mark Knecht <markknecht@gmail.com>]

Takashi,
   Since I'm on a PlanetCCRMA box I don't even have Alsa source code.
It would be quite difficult for me to test this in any short time.

   Possibly someone else out there with an HDSP box or card can do this?

Sorry,
Mark


On Tue, 18 Jan 2005 18:48:32 +0100, Takashi Iwai <tiwai@suse.de> wrote:
> At Tue, 18 Jan 2005 18:08:50 +0100,
> I wrote:
> >
> > If this works like you want, only the locking is missing...
> 
> The attached is an experimental patch to add this feature.
> You can lock system clock via
> 
>         amixer cset iface=PCM,name="System Clock Source Locking" on
> 
> It's untested, as usual.
> 
> 
> Takashi
> 
> 
> Index: alsa-kernel/pci/rme9652/hdsp.c
> ===================================================================
> RCS file: /suse/tiwai/cvs/alsa/alsa-kernel/pci/rme9652/hdsp.c,v
> retrieving revision 1.81
> diff -u -r1.81 hdsp.c
> --- alsa-kernel/pci/rme9652/hdsp.c      14 Jan 2005 19:50:48 -0000      1.81
> +++ alsa-kernel/pci/rme9652/hdsp.c      18 Jan 2005 17:44:54 -0000
> @@ -450,6 +450,7 @@
>         u32                   control2_register;     /* cached value */
>         u32                   creg_spdif;
>         u32                   creg_spdif_stream;
> +       int                   clock_source_locked;
>         char                 *card_name;             /* digiface/multiface */
>         HDSP_IO_Type          io_type;               /* ditto, but for code use */
>          unsigned short        firmware_rev;
> @@ -2159,7 +2160,7 @@
>             if (val > 6) val = 6;
>         }
>         spin_lock_irq(&hdsp->lock);
> -       if (val != hdsp_clock_source(hdsp)) {
> +       if (val != hdsp_clock_source(hdsp) && ! hdsp->clock_source_locked) {
>                 change = (hdsp_set_clock_source(hdsp, val) == 0) ? 1 : 0;
>         } else {
>                 change = 0;
> @@ -2168,6 +2169,34 @@
>         return change;
>  }
> 
> +static int snd_hdsp_info_clock_source_lock(snd_kcontrol_t *kcontrol, snd_ctl_elem_info_t * uinfo)
> +{
> +       uinfo->type = SNDRV_CTL_ELEM_TYPE_BOOLEAN;
> +       uinfo->count = 1;
> +       uinfo->value.integer.min = 0;
> +       uinfo->value.integer.max = 1;
> +       return 0;
> +}
> +
> +static int snd_hdsp_get_clock_source_lock(snd_kcontrol_t * kcontrol, snd_ctl_elem_value_t * ucontrol)
> +{
> +       hdsp_t *hdsp = snd_kcontrol_chip(kcontrol);
> +
> +       ucontrol->value.integer.value[0] = hdsp->clock_source_locked;
> +       return 0;
> +}
> +
> +static int snd_hdsp_put_clock_source_lock(snd_kcontrol_t * kcontrol, snd_ctl_elem_value_t * ucontrol)
> +{
> +       hdsp_t *hdsp = snd_kcontrol_chip(kcontrol);
> +       int change;
> +
> +       change = (int)ucontrol->value.integer.value[0] != hdsp->clock_source_locked;
> +       if (change)
> +               hdsp->clock_source_locked = ucontrol->value.integer.value[0];
> +       return change;
> +}
> +
>  #define HDSP_DA_GAIN(xname, xindex) \
>  { .iface = SNDRV_CTL_ELEM_IFACE_HWDEP, \
>    .name = xname, \
> @@ -3129,6 +3158,13 @@
>  HDSP_SPDIF_NON_AUDIO("IEC958 Non-audio Bit", 0),
>  /* 'Sample Clock Source' complies with the alsa control naming scheme */
>  HDSP_CLOCK_SOURCE("Sample Clock Source", 0),
> +{
> +       .iface = SNDRV_CTL_ELEM_IFACE_PCM,
> +       .name = "Sample Clock Source Locking",
> +       .info = snd_hdsp_info_clock_source_lock,
> +       .get = snd_hdsp_get_clock_source_lock,
> +       .put = snd_hdsp_put_clock_source_lock,
> +},
>  HDSP_SYSTEM_CLOCK_MODE("System Clock Mode", 0),
>  HDSP_PREF_SYNC_REF("Preferred Sync Reference", 0),
>  HDSP_AUTOSYNC_REF("AutoSync Reference", 0),
> @@ -3360,6 +3396,7 @@
>         snd_iprintf (buffer, "System Clock Mode: %s\n", system_clock_mode);
> 
>         snd_iprintf (buffer, "System Clock Frequency: %d\n", hdsp->system_sample_rate);
> +       snd_iprintf (buffer, "System Clock Locked: %s\n", hdsp->clock_source_locked ? "Yes" : "No");
> 
>         snd_iprintf(buffer, "\n");
> 
> @@ -3882,21 +3919,19 @@
>                 spin_unlock_irq(&hdsp->lock);
>                 return 0;
> 
> -       } else {
> -               spin_unlock_irq(&hdsp->lock);
>         }
> 
>         /* how to make sure that the rate matches an externally-set one ?
>          */
> 
> -       spin_lock_irq(&hdsp->lock);
> -       if ((err = hdsp_set_rate(hdsp, params_rate(params), 0)) < 0) {
> -               spin_unlock_irq(&hdsp->lock);
> -               _snd_pcm_hw_param_setempty(params, SNDRV_PCM_HW_PARAM_RATE);
> -               return err;
> -       } else {
> -               spin_unlock_irq(&hdsp->lock);
> +       if (! hdsp->clock_source_locked) {
> +               if ((err = hdsp_set_rate(hdsp, params_rate(params), 0)) < 0) {
> +                       spin_unlock_irq(&hdsp->lock);
> +                       _snd_pcm_hw_param_setempty(params, SNDRV_PCM_HW_PARAM_RATE);
> +                       return err;
> +               }
>         }
> +       spin_unlock_irq(&hdsp->lock);
> 
>         if ((err = hdsp_set_interrupt_interval(hdsp, params_period_size(params))) < 0) {
>                 _snd_pcm_hw_param_setempty(params, SNDRV_PCM_HW_PARAM_PERIOD_SIZE);
> @@ -4318,13 +4353,17 @@
> 
>         snd_pcm_hw_constraint_msbits(runtime, 0, 32, 24);
>         snd_pcm_hw_constraint_list(runtime, 0, SNDRV_PCM_HW_PARAM_PERIOD_SIZE, &hdsp_hw_constraints_period_sizes);
> -       if (hdsp->io_type == H9632) {
> -               runtime->hw.channels_min = hdsp->qs_out_channels;
> -               runtime->hw.channels_max = hdsp->ss_out_channels;
> +       if (hdsp->clock_source_locked) {
> +               runtime->hw.rate_min = runtime->hw.rate_max = hdsp->system_sample_rate;
> +       } else if (hdsp->io_type == H9632) {
>                 runtime->hw.rate_max = 192000;
>                 runtime->hw.rates = SNDRV_PCM_RATE_KNOT;
>                 snd_pcm_hw_constraint_list(runtime, 0, SNDRV_PCM_HW_PARAM_RATE, &hdsp_hw_constraints_9632_sample_rates);
>         }
> +       if (hdsp->io_type == H9632) {
> +               runtime->hw.channels_min = hdsp->qs_out_channels;
> +               runtime->hw.channels_max = hdsp->ss_out_channels;
> +       }
> 
>         snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_CHANNELS,
>                              snd_hdsp_hw_rule_out_channels, hdsp,
> 
> 
>


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