From 8c264d2dcbbb4296e9827fcdcd83ebb2a41fb3f9 Mon Sep 17 00:00:00 2001
From: Wim Taymans <wtaymans@redhat.com>
Date: Wed, 29 Mar 2023 11:30:40 +0200
Subject: [PATCH] alsa: in IRQ mode, disable sources while we wait

In IRQ mode, disable the ALSA fds while we wait for the graph to produce
data. Otherwise we will wake up very quickly over and over.

When we get more data, we activate the sources again to start the next
cycle.
---
 spa/plugins/alsa/alsa-pcm.c | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/spa/plugins/alsa/alsa-pcm.c b/spa/plugins/alsa/alsa-pcm.c
index d304cc1fa..92a5eaa93 100644
--- a/spa/plugins/alsa/alsa-pcm.c
+++ b/spa/plugins/alsa/alsa-pcm.c
@@ -2035,6 +2035,16 @@ static int setup_matching(struct state *state)
 	return 0;
 }
 
+static void update_sources(struct state *state, bool active)
+{
+	if (state->disable_tsched) {
+		for (int i = 0; i < state->n_fds; i++) {
+			state->source[i].mask = active ? state->pfds[i].events : 0;
+			spa_loop_update_source(state->data_loop, &state->source[i]);
+		}
+	}
+}
+
 static inline int check_position_config(struct state *state)
 {
 	uint64_t target_duration;
@@ -2207,6 +2217,8 @@ again:
 	if (SPA_UNLIKELY(!state->alsa_started && (total_written > 0 || frames == 0)))
 		do_start(state);
 
+	update_sources(state, true);
+
 	return 0;
 }
 
@@ -2448,8 +2460,9 @@ static int handle_play(struct state *state, uint64_t current_time,
 
 		spa_log_trace_fp(state->log, "%p: %d", state, io->status);
 
-		io->status = SPA_STATUS_NEED_DATA;
+		update_sources(state, false);
 
+		io->status = SPA_STATUS_NEED_DATA;
 		res = spa_node_call_ready(&state->callbacks, SPA_STATUS_NEED_DATA);
 	}
 	else {
@@ -2518,7 +2531,8 @@ static void alsa_wakeup_event(struct spa_source *source)
 			state->source[i].rmask = 0;
 		}
 
-		if (SPA_UNLIKELY(err = snd_pcm_poll_descriptors_revents(state->hndl, state->pfds, state->n_fds, &revents))) {
+		if (SPA_UNLIKELY(err = snd_pcm_poll_descriptors_revents(state->hndl,
+						state->pfds, state->n_fds, &revents))) {
 			spa_log_error(state->log, "Could not look up revents: %s",
 					snd_strerror(err));
 			return;