From: Giedrius <giedrius@blokas.io>
Date: Fri, 16 Mar 2018 16:14:31 +0000 (+0200)
Subject: Fix for Pisound's MIDI Input getting blocked for a while in rare cases.
X-Git-Tag: archive/raspbian/4.9.82-1+deb9u3+rpi1_jessie~5^2~3
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=c3d756d8350be4630c2dbfbfd45e74c3313a7df3;p=linux-4.9.git

Fix for Pisound's MIDI Input getting blocked for a while in rare cases.

There was a possible race condition which could lead to Input's FIFO queue
to be underflown, causing high amount of processing in the worker thread for
some period of time.

Signed-off-by: Giedrius Trainavicius <giedrius@blokas.io>
---

diff --git a/sound/soc/bcm/pisound.c b/sound/soc/bcm/pisound.c
index 00ae628acdd2..ab9ea1f32931 100644
--- a/sound/soc/bcm/pisound.c
+++ b/sound/soc/bcm/pisound.c
@@ -56,6 +56,12 @@ static const char *pisnd_spi_get_version(void);
 static int pisnd_midi_init(struct snd_card *card);
 static void pisnd_midi_uninit(void);
 
+enum task_e {
+	TASK_PROCESS = 0,
+};
+
+static void pisnd_schedule_process(enum task_e task);
+
 #define PISOUND_LOG_PREFIX "pisound: "
 
 #ifdef PISOUND_DEBUG
@@ -129,7 +135,7 @@ static void pisnd_input_trigger(struct snd_rawmidi_substream *substream, int up)
 {
 	if (up) {
 		pisnd_spi_set_callback(pisnd_midi_recv_callback, substream);
-		pisnd_midi_recv_callback(substream);
+		pisnd_schedule_process(TASK_PROCESS);
 	} else {
 		pisnd_spi_set_callback(NULL, NULL);
 	}
@@ -258,10 +264,6 @@ static bool pisnd_spi_has_more(void)
 	return gpiod_get_value(data_available);
 }
 
-enum task_e {
-	TASK_PROCESS = 0,
-};
-
 static void pisnd_schedule_process(enum task_e task)
 {
 	if (pisnd_spi_device != NULL &&