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McASP doesn't generate dma events when more than one serializer is active

Michal Dubiel
Prodigy 20 points
Other Parts Discussed in Thread: TMS320DM8168

Hi,

I've got a problem with McASP on TMS320DM8168 chip. I'm using ALSA davinci-mcasp driver. My goal is to capture audio on four serializers simultaneously (pins AXR0,1,2,3). I've successfully got capture on one serializer at time working, but when I try to use more than one serializer at the same time (at least two configured as recieviers), then I get no EDMA events from McASP. The following is a my platform_data for McASP:

static u8 my_mcasp0_serializer_direction[] = {

RX_MODE, RX_MODE, RX_MODE,

RX_MODE, INACTIVE_MODE, INACTIVE_MODE

};

static struct snd_platform_data my_mcasp0_data = {

.tx_dma_offset = 0x46000000,

.rx_dma_offset = 0x46000000,

.op_mode = DAVINCI_MCASP_IIS_MODE,

.num_serializer = ARRAY_SIZE(my_mcasp0_serializer_direction),

.tdm_slots = 4,

.serial_dir = my_mcasp0_serializer_direction,

.asp_chan_q = EVENTQ_2,

.version = MCASP_VERSION_2,

.txnumevt = 1,

.rxnumevt = 1,

};

 

Have anyone got similar problem, or have any ideas on that?

Thanks in advance and best regards.

Michal.

  • 0
    TI__Expert 5290 points

    Hi,

    Multi-serializer mode is not supported at the moment.

    However there are a few things you can check:

    1. From the changes you have done, it appears you are using McASP0. Since the EVM uses McASP2, just to double-check... when you say you have capture on 1 serializer working, this was on McASP0 with the same driver?
    2. Can you also check that the pin-muxing of all the serializers has been taken care of and that the correct EDMA event no. is being used.

    Regards,

    Vaibhav

  • 0 in reply to Vaibhav Bedia
    Prodigy 20 points

    Hi Vaibhav,

    Thank you for your reply. 

    Quick answers:

    1. Yes, I got McASP0 with one serializer working properly. Also McASP1 that I use for audio playback works fine with one serializer.

    2. Yes, the pin-muxing and EDMA events are set correctly. 

    I had to modify a bit McASP driver to achieve the above, but not in the area of DMA events. I've already found out why I didn't get DMA events before. It was because of wrong DMA transfers length set by the McASP driver, which doesn't take into account the fact of using more than one serializer. Unfortunately, as you've said a multi-serializer mode is not supported and a simple change to DMA transfer length is not enough to get another serializer working simultaneously. McASP driver needs more changes.

    Regards,

    Michal.

  • 0 in reply to Michal Dubiel
    Intellectual 680 points

    Hello Michal,

    i have the same issue.

    Do you have any update?

     

    I need to use 2 rx_mode serializer simultaneously on MCASP0 (dm6467).

    individually they work correctly.

     

    Regards

    Claudio

  • 0 in reply to Claudio Filipponi
    Prodigy 50 points

    Hi Michal/Claudio,

    Can you please share the buffer size change done to make single channel works.

    For me it is hanging when trying to read.

    First DMA transaction itself is not happening.

    Thanks and Regards,

    Nitish James

  • 0 in reply to Nitish James94333
    Intellectual 410 points

    Hi Michal/Claudio,

     

    You have to set the FIFO depth inline with your DMA settings. DMA acount should b equal to WORD size, bcount should be equal to FIFO depth (Numbe of Events X Number of DMA or Serializers, please check the FIFOCTL register of McASP) and the transfer size should be divided by FIFO depth i.e. ccount. Also set the DMA to operat in AB sync mode.

    I hope this should solve the problem.

     

    Regards,

    ~Ajit