Jz4740 PCM driver: check whether pcm_callback_for_more isn't NULL (fixes metronome)

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@22072 a1c6a512-1295-4272-9138-f99709370657

1 files changed, 5 insertions, 3 deletions

diff --git a/firmware/target/mips/ingenic_jz47xx/pcm-jz4740.c b/firmware/target/mips/ingenic_jz47xx/pcm-jz4740.c
index 1fbc94065b..32a14744df 100644
--- a/firmware/target/mips/ingenic_jz47xx/pcm-jz4740.c
+++ b/firmware/target/mips/ingenic_jz47xx/pcm-jz4740.c
@@ -81,11 +81,13 @@ static inline void set_dma(const void *addr, size_t size)
 
 static inline void play_dma_callback(void)
 {
-    unsigned char *start;
+    unsigned char *start = NULL;
     size_t size = 0;
-    pcm_callback_for_more(&start, &size);
 
-    if(LIKELY(size > 0))
+    if(pcm_callback_for_more)
+        pcm_callback_for_more(&start, &size);
+
+    if(LIKELY(size > 0 && start))
     {
         set_dma(start, size);
         REG_DMAC_DCCSR(DMA_AIC_TX_CHANNEL) |= DMAC_DCCSR_EN;