On 11/05/2015 11:49 PM, Caleb Crome wrote: > 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. They decreased? _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
