[ALSA] Use posix clock monotonic for PCM and timer timestamps

We need an accurate and continuous (monotonic) time sources to do
accurate synchronization among more timing sources. This patch allows
to enable monotonic timestamps for ALSA PCM devices and enables monotonic
timestamps for ALSA timer devices.

Signed-off-by: Jaroslav Kysela <perex@perex.cz>

diff --git a/include/sound/asound.h b/include/sound/asound.h
index 3ad534149c06d23fbdb306890a052d6ce44f0309..475eb71d65ba6fece13ae474f645852a95a14d54 100644 (file)
--- a/include/sound/asound.h
+++ b/include/sound/asound.h
@@ -138,7 +138,7 @@ enum {
  *                                                                           *
  *****************************************************************************/
 
-#define SNDRV_PCM_VERSION              SNDRV_PROTOCOL_VERSION(2, 0, 8)
+#define SNDRV_PCM_VERSION              SNDRV_PROTOCOL_VERSION(2, 0, 9)
 
 typedef unsigned long snd_pcm_uframes_t;
 typedef signed long snd_pcm_sframes_t;
@@ -434,10 +434,16 @@ struct snd_xfern {
        snd_pcm_uframes_t frames;
 };
 
+enum {
+       SNDRV_PCM_TSTAMP_TYPE_GETTIMEOFDAY = 0, /* gettimeofday equivalent */
+       SNDRV_PCM_TSTAMP_TYPE_MONOTONIC,        /* posix_clock_monotonic equivalent */
+       SNDRV_PCM_TSTAMP_TYPE_LAST = SNDRV_PCM_TSTAMP_TYPE_MONOTONIC,
+};
+
 enum {
        SNDRV_PCM_IOCTL_PVERSION = _IOR('A', 0x00, int),
        SNDRV_PCM_IOCTL_INFO = _IOR('A', 0x01, struct snd_pcm_info),
-       SNDRV_PCM_IOCTL_TSTAMP = _IOW('A', 0x02, int),
+       SNDRV_PCM_IOCTL_TTSTAMP = _IOW('A', 0x03, int),
        SNDRV_PCM_IOCTL_HW_REFINE = _IOWR('A', 0x10, struct snd_pcm_hw_params),
        SNDRV_PCM_IOCTL_HW_PARAMS = _IOWR('A', 0x11, struct snd_pcm_hw_params),
        SNDRV_PCM_IOCTL_HW_FREE = _IO('A', 0x12),

diff --git a/include/sound/pcm.h b/include/sound/pcm.h
index 5e9cc460075efa5ee9726d0cb282218f67355100..65f636223d392890283e16df109aea34ade635ce 100644 (file)
--- a/include/sound/pcm.h
+++ b/include/sound/pcm.h
@@ -323,6 +323,7 @@ struct snd_pcm_runtime {
 
        /* -- timer -- */
        unsigned int timer_resolution;  /* timer resolution */
+       int tstamp_type;                /* timestamp type */
 
        /* -- DMA -- */           
        unsigned char *dma_area;        /* DMA area */
@@ -952,6 +953,15 @@ void snd_pcm_timer_resolution_change(struct snd_pcm_substream *substream);
 void snd_pcm_timer_init(struct snd_pcm_substream *substream);
 void snd_pcm_timer_done(struct snd_pcm_substream *substream);
 
+static inline void snd_pcm_gettime(struct snd_pcm_runtime *runtime,
+                                  struct timespec *tv)
+{
+       if (runtime->tstamp_type == SNDRV_PCM_TSTAMP_TYPE_MONOTONIC)
+               do_posix_clock_monotonic_gettime(tv);
+       else
+               getnstimeofday(tv);
+}
+
 /*
  *  Memory
  */

diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c
index 93d7ca502730ce6b5f26a0127ae4da3013655612..db3d7e934ec3bf1655b0c4ed0a1d1e64e72f0a6d 100644 (file)
--- a/sound/core/pcm_lib.c
+++ b/sound/core/pcm_lib.c
@@ -188,7 +188,7 @@ static inline int snd_pcm_update_hw_ptr_interrupt(struct snd_pcm_substream *subs
        snd_pcm_sframes_t delta;
 
        if (runtime->tstamp_mode == SNDRV_PCM_TSTAMP_MMAP)
-               getnstimeofday((struct timespec *)&runtime->status->tstamp);
+               snd_pcm_gettime(runtime, (struct timespec *)&runtime->status->tstamp);
        pos = snd_pcm_update_hw_ptr_pos(substream, runtime);
        if (pos == SNDRV_PCM_POS_XRUN) {
                xrun(substream);

diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index 6245bdaffa6855f17cef396bbc74bacffed2124e..cdeae7c46e3b05a889a3064d9c57377f8995e39c 100644 (file)
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -598,9 +598,9 @@ int snd_pcm_status(struct snd_pcm_substream *substream,
                if (runtime->tstamp_mode == SNDRV_PCM_TSTAMP_MMAP)
                        status->tstamp = runtime->status->tstamp;
                else
-                       getnstimeofday(&status->tstamp);
+                       snd_pcm_gettime(runtime, &status->tstamp);
        } else
-               getnstimeofday(&status->tstamp);
+               snd_pcm_gettime(runtime, &status->tstamp);
        status->appl_ptr = runtime->control->appl_ptr;
        status->hw_ptr = runtime->status->hw_ptr;
        if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
@@ -688,7 +688,7 @@ static void snd_pcm_trigger_tstamp(struct snd_pcm_substream *substream)
        if (runtime->trigger_master == NULL)
                return;
        if (runtime->trigger_master == substream) {
-               getnstimeofday(&runtime->trigger_tstamp);
+               snd_pcm_gettime(runtime, &runtime->trigger_tstamp);
        } else {
                snd_pcm_trigger_tstamp(runtime->trigger_master);
                runtime->trigger_tstamp = runtime->trigger_master->runtime->trigger_tstamp;
@@ -2519,6 +2519,21 @@ static int snd_pcm_sync_ptr(struct snd_pcm_substream *substream,
                return -EFAULT;
        return 0;
 }
+
+static int snd_pcm_tstamp(struct snd_pcm_substream *substream, int __user *_arg)
+{
+       struct snd_pcm_runtime *runtime = substream->runtime;
+       int arg;
+       
+       if (get_user(arg, _arg))
+               return -EFAULT;
+       if (arg < 0 || arg > SNDRV_PCM_TSTAMP_TYPE_LAST)
+               return -EINVAL;
+       runtime->tstamp_type = SNDRV_PCM_TSTAMP_TYPE_GETTIMEOFDAY;
+       if (arg == SNDRV_PCM_TSTAMP_TYPE_MONOTONIC)
+               runtime->tstamp_type = SNDRV_PCM_TSTAMP_TYPE_MONOTONIC;
+       return 0;
+}
                
 static int snd_pcm_common_ioctl1(struct file *file,
                                 struct snd_pcm_substream *substream,
@@ -2531,8 +2546,8 @@ static int snd_pcm_common_ioctl1(struct file *file,
                return put_user(SNDRV_PCM_VERSION, (int __user *)arg) ? -EFAULT : 0;
        case SNDRV_PCM_IOCTL_INFO:
                return snd_pcm_info_user(substream, arg);
-       case SNDRV_PCM_IOCTL_TSTAMP: /* just for compatibility */
-               return 0;
+       case SNDRV_PCM_IOCTL_TTSTAMP:
+               return snd_pcm_tstamp(substream, arg);
        case SNDRV_PCM_IOCTL_HW_REFINE:
                return snd_pcm_hw_refine_user(substream, arg);
        case SNDRV_PCM_IOCTL_HW_PARAMS:

diff --git a/sound/core/timer.c b/sound/core/timer.c
index e7dc56ca4b97d6840f286fd1013f3cfde80731a1..7e5fe2d9166233b0874dc5a97c8f930c214e27c8 100644 (file)
--- a/sound/core/timer.c
+++ b/sound/core/timer.c
@@ -44,11 +44,14 @@
 #endif
 
 static int timer_limit = DEFAULT_TIMER_LIMIT;
+static int timer_tstamp_monotonic = 1;
 MODULE_AUTHOR("Jaroslav Kysela <perex@perex.cz>, Takashi Iwai <tiwai@suse.de>");
 MODULE_DESCRIPTION("ALSA timer interface");
 MODULE_LICENSE("GPL");
 module_param(timer_limit, int, 0444);
 MODULE_PARM_DESC(timer_limit, "Maximum global timers in system.");
+module_param(timer_tstamp_monotonic, int, 0444);
+MODULE_PARM_DESC(timer_tstamp_monotonic, "Use posix monotonic clock source for timestamps (default).");
 
 struct snd_timer_user {
        struct snd_timer_instance *timeri;
@@ -381,7 +384,10 @@ static void snd_timer_notify1(struct snd_timer_instance *ti, int event)
        struct snd_timer_instance *ts;
        struct timespec tstamp;
 
-       getnstimeofday(&tstamp);
+       if (timer_tstamp_monotonic)
+               do_posix_clock_monotonic_gettime(&tstamp);
+       else
+               getnstimeofday(&tstamp);
        snd_assert(event >= SNDRV_TIMER_EVENT_START &&
                   event <= SNDRV_TIMER_EVENT_PAUSE, return);
        if (event == SNDRV_TIMER_EVENT_START ||
@@ -1182,8 +1188,12 @@ static void snd_timer_user_tinterrupt(struct snd_timer_instance *timeri,
                spin_unlock(&tu->qlock);
                return;
        }
-       if (tu->last_resolution != resolution || ticks > 0)
-               getnstimeofday(&tstamp);
+       if (tu->last_resolution != resolution || ticks > 0) {
+               if (timer_tstamp_monotonic)
+                       do_posix_clock_monotonic_gettime(&tstamp);
+               else
+                       getnstimeofday(&tstamp);
+       }
        if ((tu->filter & (1 << SNDRV_TIMER_EVENT_RESOLUTION)) &&
            tu->last_resolution != resolution) {
                r1.event = SNDRV_TIMER_EVENT_RESOLUTION;