linux-kernel - [PATCH] ALSA: pcm: Add xrun counter for snd_pcm

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Message-ID: <20240809140648.3414349-1-normanbt@chromium.org>
Date: Fri,  9 Aug 2024 22:06:45 +0800
From: Norman Bintang <normanbt@...omium.org>
To: LKML <linux-kernel@...r.kernel.org>
Cc: broonie@...nel.org,
	alsa-devel@...a-project.org,
	Takashi Iwai <tiwai@...e.com>,
	cujomalainey@...omium.org,
	Norman Bintang <normanbt@...omium.org>,
	Chih-Yang Hsia <paulhsia@...omium.org>,
	David Riley <davidriley@...omium.org>
Subject: [PATCH] ALSA: pcm: Add xrun counter for snd_pcm_substream

This patch adds an xrun counter to snd_pcm_substream as an alternative
to using logs from XRUN_DEBUG_BASIC. The counter provides a way to track
the number of xrun occurences, accessible through the /proc interface.

The counter is enabled when CONFIG_SND_PCM_XRUN_DEBUG is set.

Example output:

$ cat /proc/asound/card0/pcm9p/sub0/status

owner_pid   : 1425
trigger_time: 235.248957291
tstamp      : 0.000000000
delay       : 1912
avail       : 480
avail_max   : 1920
-----
hw_ptr      : 672000
appl_ptr    : 673440
xrun_counter: 3  # (new row)

Signed-off-by: Norman Bintang <normanbt@...omium.org>
Reviewed-by: Chih-Yang Hsia <paulhsia@...omium.org>
Tested-by: Chih-Yang Hsia <paulhsia@...omium.org>
Reviewed-by: David Riley <davidriley@...omium.org>
---

 include/sound/pcm.h  | 3 +++
 sound/core/pcm.c     | 6 ++++++
 sound/core/pcm_lib.c | 3 +++
 3 files changed, 12 insertions(+)

diff --git a/include/sound/pcm.h b/include/sound/pcm.h
index ac8f3aef9205..384032b6c59c 100644
--- a/include/sound/pcm.h
+++ b/include/sound/pcm.h
@@ -498,6 +498,9 @@ struct snd_pcm_substream {
 	/* misc flags */
 	unsigned int hw_opened: 1;
 	unsigned int managed_buffer_alloc:1;
+#ifdef CONFIG_SND_PCM_XRUN_DEBUG
+	unsigned int xrun_counter; /* number of times xrun happens */
+#endif /* CONFIG_SND_PCM_XRUN_DEBUG */
 };
 
 #define SUBSTREAM_BUSY(substream) ((substream)->ref_count > 0)
diff --git a/sound/core/pcm.c b/sound/core/pcm.c
index dc37f3508dc7..290690fc2abc 100644
--- a/sound/core/pcm.c
+++ b/sound/core/pcm.c
@@ -462,6 +462,9 @@ static void snd_pcm_substream_proc_status_read(struct snd_info_entry *entry,
 	snd_iprintf(buffer, "-----\n");
 	snd_iprintf(buffer, "hw_ptr      : %ld\n", runtime->status->hw_ptr);
 	snd_iprintf(buffer, "appl_ptr    : %ld\n", runtime->control->appl_ptr);
+#ifdef CONFIG_SND_PCM_XRUN_DEBUG
+	snd_iprintf(buffer, "xrun_counter: %d\n", substream->xrun_counter);
+#endif
 }
 
 #ifdef CONFIG_SND_PCM_XRUN_DEBUG
@@ -970,6 +973,9 @@ int snd_pcm_attach_substream(struct snd_pcm *pcm, int stream,
 	substream->pid = get_pid(task_pid(current));
 	pstr->substream_opened++;
 	*rsubstream = substream;
+#ifdef CONFIG_SND_PCM_XRUN_DEBUG
+	substream->xrun_counter = 0;
+#endif /* CONFIG_SND_PCM_XRUN_DEBUG */
 	return 0;
 }
 
diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c
index 6e7905749c4a..6eaa950504cf 100644
--- a/sound/core/pcm_lib.c
+++ b/sound/core/pcm_lib.c
@@ -184,6 +184,9 @@ void __snd_pcm_xrun(struct snd_pcm_substream *substream)
 		pcm_warn(substream->pcm, "XRUN: %s\n", name);
 		dump_stack_on_xrun(substream);
 	}
+#ifdef CONFIG_SND_PCM_XRUN_DEBUG
+	substream->xrun_counter++;
+#endif
 }
 
 #ifdef CONFIG_SND_PCM_XRUN_DEBUG
-- 
2.46.0.76.ge559c4bf1a-goog