On Thu, Nov 5, 2015 at 2:40 PM, Roberto Fichera <kernel@xxxxxxxxxxxxx> wrote: > On 11/05/2015 11:25 PM, Caleb Crome wrote: >> On Thu, Nov 5, 2015 at 2:08 PM, Roberto Fichera <kernel@xxxxxxxxxxxxx> wrote: >>> 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. >> It didn't seem to. There didn't seem to be any other DMA happening in >> my system, definitely none that made the EVTRR trigger. However, I >> changed it back to the way you had it. No differences, still got a >> TON of EVTERRs. > > This might be related to SDMA request when another is pending. > >> >>> 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. >> That's 2 seconds of audio! We definitely need less buffering than >> that. We pretty much need a latency of 100ms, worst case, or 1600 >> frames, or 51,200 bytes. > > I haven't checked in detail how the DAI buffering is working, but likely > the samples are passed not in buffer size chunks but instead with less > granularity. Having a large buffer gives more chance to the SSI to not > overlap DMA requests, hence no more EVTERRs. > > I would give it a try. >> >> I did change the max buffer size to 1MB though, but I'm not sure how >> much is actually being used. > > I guess it's 64K, look for IMX_SSI_DMABUF_SIZE. > > Exactly, I changed that to 1024*1024, but still I don't get zero EVTERRs, even when I set my periods long and number of periods high. _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
