Folks,
I have borrowed part of SOF architecture for my own DSP framework development as the memory on the DSP is extremely small and wouldn't be able to support SOF.
Currently I am running into a race condition as below:
CPU DSP PCM_TRIGGER_START sof_ipc_send_msg ---->
<------Immediate ACK ipc3_wait_tx_done (wait_event_timeout) <------ POSITION update
snd_pcm_period_elapsed
As you can see TRIGGER_START didn't even finish and waiting for it to complete in ipc3_wait_tx_done function. However, before it could complete the position interrupt was issued which results in calling period_elapsed function.
In order to fix this I assume below is called in SOF framework: schedule_work(&spcm->stream[substream->stream].period_elapsed_work);
How is this design working? If the interrupt is coming too fast from the DSP than the associated function with this schedule_work will not get called as the scheduler will not get time to schedule the workqueue and elapsed function will not be called thereby not increasing the hw_ptr. How is the flow control for data transfer achieved?
I am facing the above problem in my design.
I am wondering if I can simply add one more IPC command(don't call wait_event_interruptible for this) after TRIGGER_START to start the streaming.This way schedule_work for updating period_elapsed function can be avoided and it can be called in an interrupt context.
Thanks, Variksla