From 501a80b247456288ffaeef32e679ad352aa43941 Mon Sep 17 00:00:00 2001
From: Wim Taymans <wtaymans@redhat.com>
Date: Mon, 10 Apr 2023 10:47:36 +0200
Subject: [PATCH] alsa: fix rate match when using IRQ

When using the IRQ, we are woken up based on processed samples so
compare expected and current clock times to rate match the clock.

Fixes #3144
---
 spa/plugins/alsa/alsa-pcm.c | 57 +++++++++++++++++++++----------------
 1 file changed, 32 insertions(+), 25 deletions(-)

diff --git a/spa/plugins/alsa/alsa-pcm.c b/spa/plugins/alsa/alsa-pcm.c
index 7ddd980f8..e9e05a554 100644
--- a/spa/plugins/alsa/alsa-pcm.c
+++ b/spa/plugins/alsa/alsa-pcm.c
@@ -1935,10 +1935,15 @@ static int update_time(struct state *state, uint64_t current_time, snd_pcm_sfram
 	double err, corr;
 	int32_t diff;
 
-	if (state->stream == SND_PCM_STREAM_PLAYBACK)
-		err = delay - target;
-	else
-		err = target - delay;
+	if (state->disable_tsched && !follower) {
+		err = (int64_t)(current_time - state->next_time);
+		err = err / 1e9 * state->rate;
+	} else {
+		if (state->stream == SND_PCM_STREAM_PLAYBACK)
+			err = delay - target;
+		else
+			err = target - delay;
+	}
 
 	if (SPA_UNLIKELY(state->dll.bw == 0.0)) {
 		spa_dll_set_bw(&state->dll, SPA_DLL_BW_MAX, state->threshold, state->rate);
@@ -2514,6 +2519,14 @@ static int handle_capture(struct state *state, uint64_t current_time,
 	return 0;
 }
 
+static uint64_t get_time_ns(struct state *state)
+{
+	struct timespec now;
+	if (spa_system_clock_gettime(state->data_system, CLOCK_MONOTONIC, &now) < 0)
+		return 0;
+	return SPA_TIMESPEC_TO_NSEC(&now);
+}
+
 static void alsa_wakeup_event(struct spa_source *source)
 {
 	struct state *state = source->data;
@@ -2526,6 +2539,8 @@ static void alsa_wakeup_event(struct spa_source *source)
 		int err;
 		unsigned short revents;
 
+		current_time = get_time_ns(state);
+
 		for (int i = 0; i < state->n_fds; i++) {
 			state->pfds[i].revents = state->source[i].rmask;
 			/* Reset so that we only handle all our sources' events once */
@@ -2543,17 +2558,20 @@ static void alsa_wakeup_event(struct spa_source *source)
 			spa_log_trace_fp(state->log, "Woken up with no work to do");
 			return;
 		}
-	} else if (SPA_LIKELY(state->started)) {
-		if (SPA_UNLIKELY((res = spa_system_timerfd_read(state->data_system,
+	} else {
+		if (SPA_LIKELY(state->started)) {
+			if (SPA_UNLIKELY((res = spa_system_timerfd_read(state->data_system,
 						state->timerfd, &expire)) < 0)) {
 			/* we can get here when the timer is changed since the last
-			 * timerfd wakeup, for example by do_reassign_follower() executed
-			 * in the same epoll wakeup cycle */
-			if (res != -EAGAIN)
-				spa_log_warn(state->log, "%p: error reading timerfd: %s",
-						state, spa_strerror(res));
-			return;
+				 * timerfd wakeup, for example by do_reassign_follower() executed
+				 * in the same epoll wakeup cycle */
+				if (res != -EAGAIN)
+					spa_log_warn(state->log, "%p: error reading timerfd: %s",
+							state, spa_strerror(res));
+				return;
+			}
 		}
+		current_time = state->next_time;
 	}
 
 	if (SPA_UNLIKELY((res = check_position_config(state)) < 0)) {
@@ -2562,8 +2580,6 @@ static void alsa_wakeup_event(struct spa_source *source)
 		return;
 	}
 
-	current_time = state->next_time;
-
 	if (SPA_UNLIKELY(get_status(state, current_time, &delay, &target) < 0)) {
 		spa_log_error(state->log, "get_status error");
 		state->next_time += state->threshold * 1e9 / state->rate;
@@ -2572,11 +2588,7 @@ static void alsa_wakeup_event(struct spa_source *source)
 
 #ifndef FASTPATH
 	if (SPA_UNLIKELY(spa_log_level_topic_enabled(state->log, SPA_LOG_TOPIC_DEFAULT, SPA_LOG_LEVEL_TRACE))) {
-		struct timespec now;
-		uint64_t nsec;
-		if (spa_system_clock_gettime(state->data_system, CLOCK_MONOTONIC, &now) < 0)
-		    return;
-		nsec = SPA_TIMESPEC_TO_NSEC(&now);
+		uint64_t nsec = get_time_ns(state);
 		spa_log_trace_fp(state->log, "%p: wakeup %lu %lu %"PRIu64" %"PRIu64" %"PRIi64
 				" %d %"PRIi64, state, delay, target, nsec, nsec,
 				nsec - current_time, state->threshold, state->sample_count);
@@ -2636,12 +2648,7 @@ static void clear_period_sources(struct state *state) {
 
 static int setup_sources(struct state *state)
 {
-	struct timespec now;
-	int res;
-
-	if ((res = spa_system_clock_gettime(state->data_system, CLOCK_MONOTONIC, &now)) < 0)
-		return res;
-	state->next_time = SPA_TIMESPEC_TO_NSEC(&now);
+	state->next_time = get_time_ns(state);
 
 	if (state->following) {
 		/* Disable wakeups from this node */