On 11/05/2015 10:34 PM, Caleb Crome wrote: > On Thu, Nov 5, 2015 at 3:48 AM, Roberto Fichera <kernel@xxxxxxxxxxxxx> wrote: >> On 11/05/2015 12:30 PM, Fabio Estevam wrote: >>> On Thu, Nov 5, 2015 at 8:03 AM, Roberto Fichera <kernel@xxxxxxxxxxxxx> wrote: >>> >>>> Following your suggestion, I've increased the buffer size to 2K and set the period to fifo_length - 2 (13), >>>> with that I'm now running substantially smooth except 3 EVTERR on RX DMA over 4 million of interrupts. >>>> >>>> Thanks Nicolin! I'm quite happy now! >>> That's good progress, Roberto. >>> >>> It would be nice if you and Caleb could post the patches to the mailing list. >>> > Yes, when I get something quite solid, I'd like to submit it all to > the list, and hope to get it into the kernel so nobody else has to go > through this pain again. > >> Indeed! Now the TDM is stable, I've also found the reason of the EVTERRs, which was related to some stale >> code I've used to enable and disable both RDMAE and TDMAE bits to try to reset the transfers. >> Once removed that code everything is looks ok now. >> >> Regarding patches, well, from my side there isn't nothing special compared to the original fsl_ssi.c code. >> I'm basically running against a very skinny fsl_ssi.c version, I've just setup a bit larger DMA buffer, from >> 16bytes to 2K, and now reduced the DMA period to 8 because I'm mostly comfortable with that size to simplify >> sampling exchange against DAHDI subsystem within my DMA callbacks. >> >> In a few words, my problem was related due to a DMA buffer too small. >> >> What eventually might be interesting to have is the INTRMASK and EVTERR DMA setting to trigger DMA >> related errors, but I guess this need to be discussed elsewhere. > I have implemented roberto's patch on the 4.2 kernel, and I get a huge > number of EVTERR interrupts. Something like 7200/second at 16kHz > sample rate. But strangely, the audio seems to be correct. I've notice that clearing the EVTERR bit seems restarting the given SDMA. > My patch is slightly different in that it just enables EVTERR for all > channels, not just for the SSI. Might as well see if there are any > other problems. Oh yes! This will overload the SDMA isr. How bigger is your audio buffer? In your case I guess you will need something like 16KHz * 16 channels * 2 bytes (16bits) = 512K minimum. I would try to start from 1MB or maybe more. > > And it puts the stats file at > /sys/kernel/debug/20ec000.sdma/stats > > When I aplay a file for 10 seconds I get ~366 EVTERR interrupts. > When I arecord for 10 seconds, I get 1 EVTERR interrupt > When I run my application for 10 seconds, which does full duplex, I > get 72703 EVTERR interrupts, but the data integrity checks out okay. > > Interstingly, when I enable dual fifo, it goes from about 7200 > EVTERR's/sec to about 18 EVTERRs/sec. Much better, but still a long > way from working perfectly. > Cyclic DMA is particular scatter-gater DMA list dedicated for repetitive tasks looping over the same buffer, so audio. The associated callback is triggered every period (fifo_depth-2) but the job will last only when the buffer is filled in the request length. All this "tasks" will be managed by SDMA ISR. You can follow the SG_LOOP flag if you want understand more. > When I get a 'hang' from my application (no more portaudio callbacks), > I'm actually getting repeated calls to sdma_prep_dma_cyclic, though I > don't know how that call gets triggered. But once that starts > happening, no more audio data gets through. If I remember correctly portaudio has a thread that controls your callback that receive/play all samples, but I don't remember if the callback is responsible to stop recording or playing in case of error. I've to check this in my last app. _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
