topic Re: imx6q SSI master mode playback&record simultaneously in i.MX Processors

imx6q SSI master mode playback&record simultaneously

kennychou — Wed, 26 Oct 2016 09:41:21 GMT

Hi all,

I using SSI as i2s-master then follow the step as below to get record data:

start playback in background ==> start record in foreground

==> end of playback ==> end of record

The record will force to end following end of playback even though I don't want to stop recording.

I have changed SSI as ssi-asynchronous mode to solve force stop record issue,

But it will get noise when recording first time.

Is there something I missed to set SSI correctly ?

Re: imx6q SSI master mode playback&record simultaneously

igorpadykov — Thu, 27 Oct 2016 06:42:33 GMT

Hi kenny

regarding ssi i2s-master there is some limitation mentioned

in sect.61.8.1.4 I2S Mode i.MX6DQ Reference Manual

http://cache.freescale.com/files/32bit/doc/ref_manual/IMX6DQRM.pdf

When I2S modes are entered (I2S master (01) or I2S slave (10)), the following settings
are recommended:
• Sync mode (SSI_SCR[4] =1)

probably one can try other modes

Best regards
igor
-----------------------------------------------------------------------------------------------------------------------
Note: If this post answers your question, please click the Correct Answer button. Thank you!
-----------------------------------------------------------------------------------------------------------------------

Re: imx6q SSI master mode playback&record simultaneously

kennychou — Thu, 27 Oct 2016 07:26:30 GMT

Hi igor,

Many thanks for your kindly reply.

Indeed, it's relate to SSI_SCR[4], the noise will disappear if I modify code as below:

static int _fsl_ssi_set_dai_fmt(struct fsl_ssi_private *ssi_private,
unsigned int fmt)
{

      /*if (ssi_private->cpu_dai_drv.symmetric_rates) {*/    /* Do it anyway */
            /* Need to clear RXDIR when using SYNC mode */
            srcr &= ~CCSR_SSI_SRCR_RXDIR;
            scr |= CCSR_SSI_SCR_SYN;
       /*}*/

}

But, record will fail if not enable playback in the first time.

Have a nice day!

Kenny

Re: imx6q SSI master mode playback&record simultaneously

igorpadykov — Sat, 29 Oct 2016 05:50:24 GMT

iisues for ssi simultaneous playback and capture may occur due to ssi limitations

described in Table 46-40. SSI Control Bits Requiring SSI to be Disabled Before Change
i.MX35 Reference Manual
http://www.freescale.com/files/dsp/doc/ref_manual/IMX35RM.pdf

also please check comments in linux/sound/soc/fsl/fsl_ssi.c
/**
* fsl_ssi_hw_params

Best regards
igor

Re: imx6q SSI master mode playback&record simultaneously

kennychou — Sat, 29 Oct 2016 15:24:57 GMT

Hi igor,

My solution for capture is let it work as synchronous mode if not enable playback.

The SSI will work in asynchronous mode if playback & capture simultaneously,

but need to clear RXDIR and set SYN.

Thanks,

Kenny

Re: imx6q SSI master mode playback&record simultaneously

fabio_estevam — Sat, 29 Oct 2016 19:23:38 GMT

Hi Kenny,

Could you please share your patch with us? Thanks

Re: imx6q SSI master mode playback&record simultaneously

kennychou — Mon, 31 Oct 2016 02:01:41 GMT

Hi Fabio,

Here is my patch for you reference.

Best Regards,

Kenny