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[v3,1/2] cec-follower: increase precision of Audio Rate Control active sensing

Message ID bf7ed6319a3014be8c614b7cd660959e99efed4f.1619492378.git.deborahbrouwer3563@gmail.com (mailing list archive)
State New, archived
Headers show
Series cec-follower: increase accuracy Audio Rate Control | expand

Commit Message

Deborah Brouwer April 27, 2021, 3:29 a.m. UTC 
Measure the interval since the last audio rate control message in
nanoseconds instead of seconds. Increasing the precision catches audio
rate messages that are late by less than a second.

Signed-off-by: Deborah Brouwer <deborahbrouwer3563@gmail.com>
---
 utils/cec-follower/cec-processing.cpp | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)
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Patch

diff --git a/utils/cec-follower/cec-processing.cpp b/utils/cec-follower/cec-processing.cpp
index 93db4059..fcb55df2 100644
--- a/utils/cec-follower/cec-processing.cpp
+++ b/utils/cec-follower/cec-processing.cpp
@@ -29,8 +29,8 @@ 
 /* Time between each polling message sent to a device */
 #define POLL_PERIOD 15000
 
-/* The maximum interval in seconds between audio rate messages as defined in the spec */
-#define MAX_AUD_RATE_MSG_INTERVAL 2
+/* The maximum interval in nanoseconds between audio rate messages as defined in the spec */
+#define MAX_AUD_RATE_MSG_INTERVAL_NS (2 * 1000000000ULL)
 
 struct cec_enum_values {
 	const char *type_name;
@@ -241,8 +241,8 @@  static void aud_rate_msg_interval_check(__u64 ts_new, __u64 ts_old)
 	 * turned off the audio rate control.
 	 */
 	if (ts_old) {
-		unsigned interval = (ts_new - ts_old) / 1000000000;
-		if (interval > MAX_AUD_RATE_MSG_INTERVAL) {
+		__u64 interval = ts_new - ts_old;
+		if (interval > MAX_AUD_RATE_MSG_INTERVAL_NS) {
 			warn("The interval between Audio Rate Control messages was greater\n");
 			warn("than the Maxiumum Audio Rate Message Interval (2s).\n");
 		}