[RK3288][Android6.0] 调试笔记 --- Audio驱动层判断录音数据是否异常

Platform: Rockchip
OS: Android 6.0
Kernel: 3.10.92

之前有提到上层可以通过dump pcm数据查看波形来确定录音采样的数据是否正常，这里给出驱动层查看方法。

http://blog.csdn.net/kris_fei/article/details/72763579

当一次传输完成后会调用dmaengine_pcm_dma_complete()，而rockchip其实已经添加了调试方法，只是在本文件中把宏CONFIG_ARCH_ROCKCHIP关闭了。

static void dmaengine_pcm_dma_complete(void *arg){struct snd_pcm_substream *substream = arg;struct dmaengine_pcm_runtime_data *prtd = substream_to_prtd(substream);//本文件中被undef了，要自己打开。#ifdef CONFIG_ARCH_ROCKCHIPif(debug_audio_timeout){struct snd_pcm_runtime *runtime = substream->runtime;static ktime_t before = {0},after = {0};s64 t;before = after;after = ktime_get();//t就是一次DMA传输完成时间间隔。t = ktime_to_us(ktime_sub(after, before));//右边的表示理论DMA一次传输需要的时间，单位是us,+32可能是rk经过测试之后可以容忍的出错帧数。//当条件成立的时候，说明DMA没出完完成，这时就会有问题了。if(t > (snd_pcm_lib_period_bytes(substream)/4+32)*1000*1000/runtime->rate&& t != ktime_to_us(after)) // (23220)4096/4/44100 + 32/44100{//当在kmsg中频繁看到这条Log音频应该有异常了。printk(KERN_DEBUG "Time out:: Audio DMA buffdone time out!!! the time = %lld!\n", t);}//printk(KERN_DEBUG "audio DMA callback time = %lld\n", t);}#endifprtd->pos += snd_pcm_lib_period_bytes(substream);if (prtd->pos >= snd_pcm_lib_buffer_bytes(substream))prtd->pos = 0;snd_pcm_period_elapsed(substream);}