On 11/06/2015 12:21 AM, Caleb Crome wrote: > On Thu, Nov 5, 2015 at 3:01 PM, Roberto Fichera <kernel@xxxxxxxxxxxxx> wrote: >> >> 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? >> > the big win was going to dual fifo, but they're still there at > something like 17/second. What about your current fifo_depth? Are you using the full length? _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
