Hello Folks,
I have a DSP hardware connected over SPI to SoC with extra interrupt line.
I am getting buffer overrun problem in DSP while doing MIC recording. SoC SPI consecutive reads are two slow and it is not able to empty DSP buffers in time which causes DSP to issue overruns interrupts to SoC and causes bad mic data recording.
ARECORD properly records mic data but when I try to use AudioFlinger(android) then I see buffer overrun issue in DSP. Period size is same in both arecord and AudioFlinger case.
system: arm64, latest mainline kernel, latest alsa-lib
I have below platform ops static const struct snd_pcm_ops platform_ops = { .open = platform_open, .ioctl = snd_pcm_lib_ioctl, .pointer = platform_pcm_pointer, .mmap = snd_pcm_lib_default_mmap, .page = snd_pcm_lib_get_vmalloc_page, };
What baffles me is that consecutive SPI read(while loop in a workqueue) doesn't have any relation with userspace as it is interrupt driven (DSP interrupt) but still with audio flinger overrun happens. In the workqueue, between SPI reads, driver calls elapsed function to notify the userspace to read 1 period data whenever data crosses period boundary. I don't think that causes any issues. Aforementioned workqueue stops only when userspace closes it so I don't know how userspace application can slow down SPI reads?
I have also used high priority workqueues but that didn't help either. Wondering if I can get some pointers to debug this? also if there any alsa-utility which can simulate closely audio flinger?
Thanks,