Re: [PATCH 4/4] ASoC: ti: davinci-mcasp: Add asynchronous mode support

[Sen Wang]

On 2/2/26 11:02, Péter Ujfalusi wrote:
> On 30/01/2026 07:10, Sen Wang wrote:
> > McASP has dedicated clock & frame sync registers for both transmit
> > and receive. Currently McASP driver only supports synchronous behavior and
> > couples both TX & RX settings.
> >
> > Add logic that enables asynchronous mode via ti,async-mode property. In
> > async mode, playback & record can be done simultaneously with different
> > audio configurations (tdm slots, tdm width, audio bit depth).
> >
> > Note the ability to have different tx/rx DSP formats (i2s, dsp_a, etc.),
> > while possible in hardware, remains to be a gap as it require changes
> > to the corresponding machine driver interface.
> >
> > Existing IIS (sync mode) and DIT mode logic remains mostly unchanged.
> > Exceptions are IIS mode logic that previously assumed sync mode, which has
> > now been made aware of the distinction. And shared logic across all modes
> > also now checks for McASP tx/rx-specific driver attributes. Those
> > attributes have been populated according to the original extent, ensuring
> > no divergence in functionality.
> >
> > Constraints no longer applicable for async mode are skipped.
> > Clock selection options have also been added to include rx/tx-only clk_ids,
> > exposing independent configuration via the machine driver as well.
> >
> > Note that asynchronous mode is not applicable for McASP in DIT mode,
> > which is a transmitter-only mode to interface w/ self-clocking formats.
> >
> > Signed-off-by: Sen Wang <sen@xxxxxx>
> > ---
> >   include/linux/platform_data/davinci_asp.h |   3 +-
> >   sound/soc/ti/davinci-mcasp.c              | 487 +++++++++++++++++-----
> >   sound/soc/ti/davinci-mcasp.h              |  10 +
> >   3 files changed, 398 insertions(+), 102 deletions(-)
> >
> > diff --git a/sound/soc/ti/davinci-mcasp.c b/sound/soc/ti/davinci-mcasp.c
>
>    static void mcasp_start_rx(struct davinci_mcasp *mcasp)
> >   {
> >   	if (mcasp->rxnumevt) {	/* enable FIFO */
> > @@ -230,13 +288,17 @@ static void mcasp_start_rx(struct davinci_mcasp *mcasp)
> >   	/*
> >   	 * When ASYNC == 0 the transmit and receive sections operate
> >   	 * synchronously from the transmit clock and frame sync. We need to make
> > -	 * sure that the TX signlas are enabled when starting reception.
> > +	 * sure that the TX signals are enabled when starting reception.
> > +	 * Else set pin to be output when McASP is the master
>
> In new code - while it might not match with old code - use producer
> instead of master.
>
> Otherwise it looks nice, I trust you have tested the sync and DIT mode.
>
> With this nitpick addressed:
> Acked-by: Peter Ujfalusi <peter.ujfalusi@xxxxxxxxx>

Hi Péter, thanks for your review

I'll use inclusive terminology (producer) instead.

I've functionally tested IIS sync mode. For DIT mode, since I don't have 
hardware available, I've only done a register dump in comparison, during
idle, playback & shutdown - all registers in effect stay unchanged.

Will post a V2 shortly with all the corrections.

Best,
Sen Wang