Re: [PATCH 09/13] ASoC: ti: davinci-i2s: Enable unexpected frame pulses detection

[Bastien Curutchet]

Hi Mark,

On 3/15/24 15:09, Mark Brown wrote:
> On Fri, Mar 15, 2024 at 12:27:41PM +0100, Bastien Curutchet wrote:
>
> > McBSP can generate an SYNCERR when unexpected frame pulses are
> > detected. The driver always disables this feature and ignore the
> > unexpected frame pulses.
>
> What does "unexpected" mean?

Unexpected frame sync pulse is defined in datasheet as a sync pulse that 
occurs <N> bit clocks earlier than the last transmitted bit of the 
previous frame. The <N> can be configured through registers.

> > Enable the generation of SYNCERR by the McBSP according to the
> > 'ti,enable-sync-err' device-tree property.
>
> Why would this be optional, and how is this reported - I'm not seeing
> any interrupt handling updates?

It is possible to deliberately ignore them and that is what is done 
today in the driver.
This is reported as a status bit in a register. An interrupt can indeed 
be generated from this but I'm not using it (now at least).
I use the fact that McBSP automatically drops previous element and 
starts a new reception when an unexpected frame pulse occurs.


Best regards,
Bastien