[alsa-devel] [RFC 6/7] ASoC: hda: Add support for SSP register settings

[Vinod Koul]

On Wed, Apr 29, 2015 at 06:50:14PM -0500, Pierre-Louis Bossart wrote:
> 
> >>>>>+        /* Dont add odd number of dummy bits, since I2S requires
> >>>>>+         * dummy bit after each slot/channel
> >>>>>+         */
> >>
> >>>>It does?
> >>
> >>>For us unfortuntely yes. We send 24 bit audio to codec and clock divider
> >>>doesn't give us 48clocks per frame, so we have to add dummy clocks in
> >>>each
> >>>slot and send 25 clocks per slot
> >>
> >>So it's the hardware rather than I2S itself :)
> >
> >It depends on the clock reference used to drive the SSP. With a 19.2
> >reference we typically divide by 50 and pad with a trailing bit.
> >
> >That said I am not sure how this code would work on SKL. Vinod, isn't
> >this for BXT only? how do you get 19.2 on SKL, shouldn't you guys use a
> >24 MHz root frequency to find the divider?
> 
> And regardless you should make sure that the actual blck does not
> exceed the maximum serial bit-rate supported by the SOC (AC timing).
Yes botha re valid points. But I do rember one of the platforms has 10.2 and
another has 25, so we need to be agnostic here and do compare, or use ACPI
blobs :)

-- 
~Vinod