jz47xx: Audio path tweaks:

 * Increase audio buffer size to better handle IRQ latency (256->2048)
 * Ensure DMA engine is idle prior to starting transfers
 * Set AIC to repeat last sample in case of underflows

Change-Id: I9c45c20481ee072e5882b7586fb7d50bd8ef2f35

1 files changed, 4 insertions, 0 deletions

diff --git a/firmware/export/pcm_mixer.h b/firmware/export/pcm_mixer.h
index b418a5d347..3d255a7345 100644
--- a/firmware/export/pcm_mixer.h
+++ b/firmware/export/pcm_mixer.h
@@ -30,6 +30,10 @@
 #if CONFIG_CPU == PP5002
 /* There's far less time to do mixing because HW FIFOs are short */
 #define MIX_FRAME_SAMPLES 64
+#elif (CONFIG_CPU == JZ4760B) || (CONFIG_CPU == JZ4732)
+/* These MIPS32r1 targets have a very high interrupt latency, which
+   unfortunately causes a lot of audio underruns under even moderate load */
+#define MIX_FRAME_SAMPLES 2048
 #elif (CONFIG_PLATFORM & PLATFORM_MAEMO5) || defined(DX50) || defined(DX90)
 /* Maemo 5 needs 2048 samples for decent performance.
    Otherwise the locking overhead inside gstreamer costs too much */