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authorTakashi Sakamoto <o-takashi@sakamocchi.jp>2018-10-01 04:11:49 +0900
committerTakashi Iwai <tiwai@suse.de>2018-10-02 17:28:29 +0200
commit5950229582bc4e5e332247dd9ec11e6fe85659e1 (patch)
tree15b387e2ffb9371d55899b7c9a4ade37b762f338 /sound
parent96395e86e3f4c7f520bb7c53c7eee41b1992ebc2 (diff)
downloadlinux-5950229582bc4e5e332247dd9ec11e6fe85659e1.tar.gz
ALSA: firewire-lib: add PCM rules to obsolete PCM constraints based on LCM of SYT_INTERVAL
In blocking mode of IEC 61883-1/6, when one isochronous packet includes data for events, the data is for the same number of events as SYT_INTERVAL decided according to sampling transmission frequency (SFC). IEC 61883-1/6 engine of ALSA firewire stack applies constraints of period and buffer size of PCM intermediate buffer of PCM substream. At present, this constraint is designed to round the size up/down to 32 frames. This value comes from the least common multiple (LCM) of SYT_INTERVAL. Although this looks to work well, in lower sampling rate, applications are not allowed to set size of period quite near period time constraint (at present 5 msec per period). This commit adds PCM rules for period/buffer size and rate to obsoletes the constraints based on LCM. Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp> Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound')
-rw-r--r--sound/firewire/amdtp-stream.c78
1 files changed, 71 insertions, 7 deletions
diff --git a/sound/firewire/amdtp-stream.c b/sound/firewire/amdtp-stream.c
index cb9acfe60f6a..fcd965f1d69e 100644
--- a/sound/firewire/amdtp-stream.c
+++ b/sound/firewire/amdtp-stream.c
@@ -140,6 +140,59 @@ const unsigned int amdtp_rate_table[CIP_SFC_COUNT] = {
};
EXPORT_SYMBOL(amdtp_rate_table);
+static int apply_constraint_to_size(struct snd_pcm_hw_params *params,
+ struct snd_pcm_hw_rule *rule)
+{
+ struct snd_interval *s = hw_param_interval(params, rule->var);
+ const struct snd_interval *r =
+ hw_param_interval_c(params, SNDRV_PCM_HW_PARAM_RATE);
+ struct snd_interval t = {
+ .min = s->min, .max = s->max, .integer = 1,
+ };
+ int i;
+
+ for (i = 0; i < CIP_SFC_COUNT; ++i) {
+ unsigned int rate = amdtp_rate_table[i];
+ unsigned int step = amdtp_syt_intervals[i];
+
+ if (!snd_interval_test(r, rate))
+ continue;
+
+ t.min = roundup(t.min, step);
+ t.max = rounddown(t.max, step);
+ }
+
+ if (snd_interval_checkempty(&t))
+ return -EINVAL;
+
+ return snd_interval_refine(s, &t);
+}
+
+static int apply_constraint_to_rate(struct snd_pcm_hw_params *params,
+ struct snd_pcm_hw_rule *rule)
+{
+ struct snd_interval *r =
+ hw_param_interval(params, SNDRV_PCM_HW_PARAM_RATE);
+ const struct snd_interval *s = hw_param_interval_c(params, rule->deps[0]);
+ struct snd_interval t = {
+ .min = UINT_MAX, .max = 0, .integer = 1,
+ };
+ int i;
+
+ for (i = 0; i < CIP_SFC_COUNT; ++i) {
+ unsigned int step = amdtp_syt_intervals[i];
+ unsigned int rate = amdtp_rate_table[i];
+
+ if (s->min % step || s->max % step)
+ continue;
+
+ t.min = min(t.min, rate);
+ t.max = max(t.max, rate);
+ }
+
+ return snd_interval_refine(r, &t);
+}
+
/**
* amdtp_stream_add_pcm_hw_constraints - add hw constraints for PCM substream
* @s: the AMDTP stream, which must be initialized.
@@ -194,16 +247,27 @@ int amdtp_stream_add_pcm_hw_constraints(struct amdtp_stream *s,
* number equals to SYT_INTERVAL. So the number is 8, 16 or 32,
* depending on its sampling rate. For accurate period interrupt, it's
* preferrable to align period/buffer sizes to current SYT_INTERVAL.
- *
- * TODO: These constraints can be improved with proper rules.
- * Currently apply LCM of SYT_INTERVALs.
*/
- err = snd_pcm_hw_constraint_step(runtime, 0,
- SNDRV_PCM_HW_PARAM_PERIOD_SIZE, 32);
+ err = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_PERIOD_SIZE,
+ apply_constraint_to_size, NULL,
+ SNDRV_PCM_HW_PARAM_RATE, -1);
+ if (err < 0)
+ goto end;
+ err = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_RATE,
+ apply_constraint_to_rate, NULL,
+ SNDRV_PCM_HW_PARAM_PERIOD_SIZE, -1);
+ if (err < 0)
+ goto end;
+ err = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_BUFFER_SIZE,
+ apply_constraint_to_size, NULL,
+ SNDRV_PCM_HW_PARAM_RATE, -1);
+ if (err < 0)
+ goto end;
+ err = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_RATE,
+ apply_constraint_to_rate, NULL,
+ SNDRV_PCM_HW_PARAM_BUFFER_SIZE, -1);
if (err < 0)
goto end;
- err = snd_pcm_hw_constraint_step(runtime, 0,
- SNDRV_PCM_HW_PARAM_BUFFER_SIZE, 32);
end:
return err;
}