pcm: direct: allow users to configure different period sizes

This patch allows the effective period size to be a multiple of the
slave-pcm period size.
Allowing only exact multiple of original period size is achieved by
borrowing code from the kernel hwrules implementation.

This patch is intended to save cpu workload when for example, the
slave operates with very small periods but a user does not need that
small periods.

This feature is enabled by default and can be disabled by adding
config option 'var_periodsize 0'.

Signed-off-by: Alexander Jahn <ajahn@de.adit-jv.com>
Signed-off-by: Andreas Pape <apape@de.adit-jv.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/src/pcm/pcm_direct.c b/src/pcm/pcm_direct.c
index 643498375b3424625c629ae2d75554b95e098940..f5d922fdc8c871c6c16c43c1460db2e748260517 100644 (file)
--- a/src/pcm/pcm_direct.c
+++ b/src/pcm/pcm_direct.c
@@ -660,6 +660,29 @@ static int hw_param_interval_refine_minmax(snd_pcm_hw_params_t *params,
        return hw_param_interval_refine_one(params, var, &t);
 }
 
+/* this code is used 'as-is' from the alsa kernel code */
+static int snd_interval_step(struct snd_interval *i, unsigned int min,
+                            unsigned int step)
+{
+       unsigned int n;
+       int changed = 0;
+       n = (i->min - min) % step;
+       if (n != 0 || i->openmin) {
+               i->min += step - n;
+               changed = 1;
+       }
+       n = (i->max - min) % step;
+       if (n != 0 || i->openmax) {
+               i->max -= n;
+               changed = 1;
+       }
+       if (snd_interval_checkempty(i)) {
+               i->empty = 1;
+               return -EINVAL;
+       }
+       return changed;
+}
+
 #undef REFINE_DEBUG
 
 int snd_pcm_direct_hw_refine(snd_pcm_t *pcm, snd_pcm_hw_params_t *params)
@@ -710,15 +733,16 @@ int snd_pcm_direct_hw_refine(snd_pcm_t *pcm, snd_pcm_hw_params_t *params)
                                           &dshare->shmptr->hw.rate);
        if (err < 0)
                return err;
-       err = hw_param_interval_refine_one(params, SND_PCM_HW_PARAM_PERIOD_SIZE,
-                                          &dshare->shmptr->hw.period_size);
-       if (err < 0)
-               return err;
-       err = hw_param_interval_refine_one(params, SND_PCM_HW_PARAM_PERIOD_TIME,
-                                          &dshare->shmptr->hw.period_time);
-       if (err < 0)
-               return err;
+
        if (dshare->max_periods < 0) {
+               err = hw_param_interval_refine_one(params, SND_PCM_HW_PARAM_PERIOD_SIZE,
+                                                  &dshare->shmptr->hw.period_size);
+               if (err < 0)
+                       return err;
+               err = hw_param_interval_refine_one(params, SND_PCM_HW_PARAM_PERIOD_TIME,
+                                                  &dshare->shmptr->hw.period_time);
+               if (err < 0)
+                       return err;
                err = hw_param_interval_refine_one(params, SND_PCM_HW_PARAM_BUFFER_SIZE,
                                                   &dshare->shmptr->hw.buffer_size);
                if (err < 0)
@@ -730,11 +754,38 @@ int snd_pcm_direct_hw_refine(snd_pcm_t *pcm, snd_pcm_hw_params_t *params)
        } else if (params->rmask & ((1<<SND_PCM_HW_PARAM_PERIODS)|
                                    (1<<SND_PCM_HW_PARAM_BUFFER_BYTES)|
                                    (1<<SND_PCM_HW_PARAM_BUFFER_SIZE)|
-                                   (1<<SND_PCM_HW_PARAM_BUFFER_TIME))) {
+                                   (1<<SND_PCM_HW_PARAM_BUFFER_TIME)|
+                                   (1<<SND_PCM_HW_PARAM_PERIOD_TIME)|
+                                   (1<<SND_PCM_HW_PARAM_PERIOD_SIZE)|
+                                   (1<<SND_PCM_HW_PARAM_PERIOD_BYTES))) {
+               snd_interval_t period_size = dshare->shmptr->hw.period_size;
+               snd_interval_t period_time = dshare->shmptr->hw.period_time;
                int changed;
                unsigned int max_periods = dshare->max_periods;
                if (max_periods < 2)
                        max_periods = dshare->slave_buffer_size / dshare->slave_period_size;
+
+               /* make sure buffer size does not exceed slave buffer size */
+               err = hw_param_interval_refine_minmax(params, SND_PCM_HW_PARAM_BUFFER_SIZE,
+                                       2 * dshare->slave_period_size, dshare->slave_buffer_size);
+               if (err < 0)
+                       return err;
+               if (dshare->var_periodsize) {
+                       /* more tolerant settings... */
+                       if (dshare->shmptr->hw.buffer_size.max / 2 > period_size.max)
+                               period_size.max = dshare->shmptr->hw.buffer_size.max / 2;
+                       if (dshare->shmptr->hw.buffer_time.max / 2 > period_time.max)
+                               period_time.max = dshare->shmptr->hw.buffer_time.max / 2;
+               }
+
+               err = hw_param_interval_refine_one(params, SND_PCM_HW_PARAM_PERIOD_SIZE,
+                                                  &period_size);
+               if (err < 0)
+                       return err;
+               err = hw_param_interval_refine_one(params, SND_PCM_HW_PARAM_PERIOD_TIME,
+                                                  &period_time);
+               if (err < 0)
+                       return err;
                do {
                        changed = 0;
                        err = hw_param_interval_refine_minmax(params, SND_PCM_HW_PARAM_PERIODS,
@@ -746,8 +797,16 @@ int snd_pcm_direct_hw_refine(snd_pcm_t *pcm, snd_pcm_hw_params_t *params)
                        if (err < 0)
                                return err;
                        changed |= err;
+                       err = snd_interval_step(hw_param_interval(params, SND_PCM_HW_PARAM_PERIOD_SIZE),
+                                                               0, dshare->slave_period_size);
+                       if (err < 0)
+                               return err;
+                       changed |= err;
+                       if (err)
+                               params->rmask |= (1 << SND_PCM_HW_PARAM_PERIOD_SIZE);
                } while (changed);
        }
+       dshare->timer_ticks = hw_param_interval(params, SND_PCM_HW_PARAM_PERIOD_SIZE)->max / dshare->slave_period_size;
        params->info = dshare->shmptr->s.info;
 #ifdef REFINE_DEBUG
        snd_output_puts(log, "DMIX REFINE (end):\n");
@@ -1183,6 +1242,7 @@ int snd_pcm_direct_initialize_poll_fd(snd_pcm_direct_t *dmix)
 
        dmix->tread = 1;
        dmix->timer_need_poll = 0;
+       dmix->timer_ticks = 1;
        ret = snd_pcm_info(dmix->spcm, &info);
        if (ret < 0) {
                SNDERR("unable to info for slave pcm");
@@ -1366,7 +1426,7 @@ int snd_pcm_direct_set_timer_params(snd_pcm_direct_t *dmix)
        snd_timer_params_set_auto_start(&params, 1);
        if (dmix->type != SND_PCM_TYPE_DSNOOP)
                snd_timer_params_set_early_event(&params, 1);
-       snd_timer_params_set_ticks(&params, 1);
+       snd_timer_params_set_ticks(&params, dmix->timer_ticks);
        if (dmix->tread) {
                filter = (1<<SND_TIMER_EVENT_TICK) |
                         dmix->timer_events;
@@ -1656,6 +1716,7 @@ int snd_pcm_direct_parse_open_conf(snd_config_t *root, snd_config_t *conf,
        rec->ipc_gid = -1;
        rec->slowptr = 1;
        rec->max_periods = 0;
+       rec->var_periodsize = 1;
 
        /* read defaults */
        if (snd_config_search(root, "defaults.pcm.dmix_max_periods", &n) >= 0) {
@@ -1762,6 +1823,13 @@ int snd_pcm_direct_parse_open_conf(snd_config_t *root, snd_config_t *conf,
                        rec->max_periods = val;
                        continue;
                }
+               if (strcmp(id, "var_periodsize") == 0) {
+                       err = snd_config_get_bool(n);
+                       if (err < 0)
+                               return err;
+                       rec->var_periodsize = err;
+                       continue;
+               }
                SNDERR("Unknown field %s", id);
                return -EINVAL;
        }

diff --git a/src/pcm/pcm_direct.h b/src/pcm/pcm_direct.h
index 611ad29a4821ec43ce3d64335d011d568ef8af45..91e816cccb8e22539f12f7ace93e271dec0e353e 100644 (file)
--- a/src/pcm/pcm_direct.h
+++ b/src/pcm/pcm_direct.h
@@ -147,12 +147,14 @@ struct snd_pcm_direct {
        int tread: 1;
        int timer_need_poll: 1;
        unsigned int timer_events;
+       unsigned int timer_ticks;
        int server_fd;
        pid_t server_pid;
        snd_timer_t *timer;             /* timer used as poll_fd */
        int interleaved;                /* we have interleaved buffer */
        int slowptr;                    /* use slow but more precise ptr updates */
        int max_periods;                /* max periods (-1 = fixed periods, 0 = max buffer size) */
+       int var_periodsize;             /* allow variable period size if max_periods is != -1*/
        unsigned int channels;          /* client's channels */
        unsigned int *bindings;
        union {
@@ -326,6 +328,7 @@ struct snd_pcm_direct_open_conf {
        int ipc_gid;
        int slowptr;
        int max_periods;
+       int var_periodsize;
        snd_config_t *slave;
        snd_config_t *bindings;
 };

diff --git a/src/pcm/pcm_dmix.c b/src/pcm/pcm_dmix.c
index 825677ffeb3f6f8b2b90dbdc077c41e87bb1eb9f..0ab73233898463f88734ee31927a92b73c005dad 100644 (file)
--- a/src/pcm/pcm_dmix.c
+++ b/src/pcm/pcm_dmix.c
@@ -1040,6 +1040,7 @@ int snd_pcm_dmix_open(snd_pcm_t **pcmp, const char *name,
        dmix->state = SND_PCM_STATE_OPEN;
        dmix->slowptr = opts->slowptr;
        dmix->max_periods = opts->max_periods;
+       dmix->var_periodsize = opts->var_periodsize;
        dmix->sync_ptr = snd_pcm_dmix_sync_ptr;
 
  retry:

diff --git a/src/pcm/pcm_dshare.c b/src/pcm/pcm_dshare.c
index 29cd6c6da1d049dd8b9f97f916cb6942a2e9557c..a1fed5dfb0ecf2ca2d40faf8aa25c5acaacfe9b1 100644 (file)
--- a/src/pcm/pcm_dshare.c
+++ b/src/pcm/pcm_dshare.c
@@ -725,6 +725,7 @@ int snd_pcm_dshare_open(snd_pcm_t **pcmp, const char *name,
        dshare->state = SND_PCM_STATE_OPEN;
        dshare->slowptr = opts->slowptr;
        dshare->max_periods = opts->max_periods;
+       dshare->var_periodsize = opts->var_periodsize;
        dshare->sync_ptr = snd_pcm_dshare_sync_ptr;
 
  retry:

diff --git a/src/pcm/pcm_dsnoop.c b/src/pcm/pcm_dsnoop.c
index 1aedf3cb73d229eb3b695ebbe6de9e3c148e719f..85f0ff4cbb1136715c1995efe6356b9cdd7f7759 100644 (file)
--- a/src/pcm/pcm_dsnoop.c
+++ b/src/pcm/pcm_dsnoop.c
@@ -606,6 +606,7 @@ int snd_pcm_dsnoop_open(snd_pcm_t **pcmp, const char *name,
        dsnoop->state = SND_PCM_STATE_OPEN;
        dsnoop->slowptr = opts->slowptr;
        dsnoop->max_periods = opts->max_periods;
+       dsnoop->var_periodsize = opts->var_periodsize;
        dsnoop->sync_ptr = snd_pcm_dsnoop_sync_ptr;
 
  retry: