linux-kernel - Re: [PATCH v3 17/20] ASoC: dt-bindings: tas2770: add flags for SDOUT pulldown and zero-fill

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Message-ID: <20250312125832.GA359842-robh@kernel.org>
Date: Wed, 12 Mar 2025 07:58:32 -0500
From: Rob Herring <robh@...nel.org>
To: James Calligeros <jcalligeros99@...il.com>
Cc: Liam Girdwood <lgirdwood@...il.com>, Mark Brown <broonie@...nel.org>,
	Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.com>,
	Shenghao Ding <shenghao-ding@...com>, Kevin Lu <kevin-lu@...com>,
	Baojun Xu <baojun.xu@...com>, Dan Murphy <dmurphy@...com>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Shi Fu <shifu0704@...ndersoft.com>,
	Jean Delvare <jdelvare@...e.com>,
	Guenter Roeck <linux@...ck-us.net>,
	Alyssa Rosenzweig <alyssa@...enzweig.io>,
	Martin Povišer <povik+lin@...ebit.org>,
	Hector Martin <marcan@...can.st>, linux-sound@...r.kernel.org,
	linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
	asahi@...ts.linux.dev, linux-hwmon@...r.kernel.org
Subject: Re: [PATCH v3 17/20] ASoC: dt-bindings: tas2770: add flags for SDOUT
 pulldown and zero-fill

On Mon, Mar 10, 2025 at 07:30:07PM +1000, James Calligeros wrote:
> On Sat, Mar 8, 2025 at 6:51 AM Rob Herring <robh@...nel.org> wrote:
> > How would it work when you need a mask? "dai-tdm-slot-tx-mask" is
> > enough?
> 
> The existing TX/RX slot masks are used to control which slots the codec
> is operating on, AIUI. I don't know if it makes sense to alter how codecs
> deal with this. Could we combine the suggested dai-tdm-slot-tx-idle
> with an optional dai-tdm-slot-tx-idle-mask property? From the machine
> driver's perspective, the API would then be similar to the existing
> set_tdm_slot ops. The current downstream macaudio machine driver builds
> its links by allowing multiple codecs and CPUs to be linked to a DAI,
> like so:

Wouldn't the NOT of dai-tdm-slot-tx-mask be the idle mask?

Don't think about the Linux APIs here. The DT is separate. So think in 
terms of what you need to describe the TDM timing/waveform.

> 
> dai-link@0 {
> 	cpu {
> 		sound-dai = <&cpu0>, <&cpu1>;
> 	};
> 	codec {
> 		sound-dai = <&speaker0>,
> 			  ...,
> 			  <&speaker6>;
> 	};
> };
> 
> In this case, the codec-specific mask property was added so that a mask
> could be applied to a specific codec rather than the whole dai, however
> from upstream drivers tt looks like the way this should be handled is to
> have "dai-tdm-slot-tx-idle-mask-n" properties at the dai level, then have
> the machine driver set the mask for the appropriate codec during setup. So
> for macaudio, assuming speaker5 requires this zerofill mask, we would
> have something like this:

I'm now confused why you need n masks and what does n represent?

Rob