Re: [PATCH QUESTION] ASoC: qcom: sdm845: use DSP_A format for TDM codec DAIs

[Richard Acayan <mailingradian@gmail.com>]

On Sun, Jun 21, 2026 at 05:54:17PM +0200, David Heidelberg wrote:
> On 14/06/2026 23:40, Srinivas Kandagatla wrote:
> > On 6/14/26 8:26 AM, David Heidelberg wrote:
> > > On 14/06/2026 01:53, Mark Brown wrote:
> > > > On Sat, Jun 13, 2026 at 09:55:59PM +0200, David Heidelberg via B4
> > > > Relay wrote:
> > > > 
> > > > > Currently this worked only because the cs35l36
> > > > > codec mapped both DSP_A and DSP_B to the same hardware register value
> > > > > (asp_fmt = 0), which is inherently DSP_A timing.
> > > > 
> > > > > The CPU-side AFE is configured with qcom,tdm-data-delay = <1> which

No I don't think so, this devicetree property has no effect in
sound/soc/qcom/qdsp6/q6afe-dai.c.

For the Pixel 3a, it only mattered with the RT5514 codec.

> > > > > produces DSP_A framing.
> > > > > The codec format should match what is actually on the wire.
> > > > 
> > > > > So I'm pretty lost if I should go fixing cs35l36 or sdm845.c.
> > > > 
> > > > That sounds like both.  The Cirrus driver is definitely buggy if it's
> > > > mapping DSP A and B to the same register value, at least one of those is
> > > > wrong.
> > > 
> > > I need to clarify. The CS35L36 supports by default only DSP_A, but when
> > > extended to "take DSP_B", speaker just works.
> > > 
> > > This was done previously.
> > > 
> > > Since there isn't any different configuration on the codec side when
> > > added DSP_B into same codepath as DSP_A, I would assume QCOM ASoC send
> > > DSP_A, just marking it as DSP_B ?
> > 
> > 
> > 		qcom,tdm-sync-mode = <0>;
> > 		qcom,tdm-sync-src = <1>;
> > sets the short sync with 1 clk delay making it DSP_A.
> > 
> > for DSP_B you would need, no delay.
> 
> Sure, does that mean the sdm845.c is currently correctly setting
> SND_SOC_DAIFMT_DSP_B there? or there is some missing part of logic deciding
> it?
> 
> Because the reason audio works when I convince driver either:
> 
> a) sdm845 ASoC it uses BSP_A instead of B ... or
> b) cs35l36 it uses BSP_B instead of A
> 
> implies to me, that:
>  1. both devices are setting the HW to either BSP_A or BSP_B mode (just
> don't know which one)
>  2. but the driver flag for ASoC or codec we setting on the driver side is wrong
> 
> If one side really used BSP_A and other BSP_B, the audio should be at best
> heavily distorted, right?
> 
> Please correct me, if I misunderstood or if there is nice doc I could read about it.
> 
> Thanks
> David
> 
> P.S. I did quick search what close-to-mainline repo has for Pixel 3a to
> reach working audio and it's slightly different, see [1]. There isn't any
> change done to the cs35l36 driver in the sdm670 tree.

I just assumed DSP_A and DSP_B were codec-specific.

> [1] https://gitlab.com/sdm670-mainline/linux/-/commit/9eba5aa993f5fb7b4bf5cc936ec22852987d3f9f