Re: [PATCH] ASoC: tas2783-sdw: power the Function up before preparing the port

Mark Brown <[email protected]> Thu, 13 Aug 2026 14:22:52 +0100

Newsgroups	org.kernel.vger.linux-sound,org.kernel.vger.linux-kernel
Message-ID	<[email protected]>

On Thu, Aug 13, 2026 at 12:28:10AM +0300, Andrey Golovko wrote:

> A Data Port cannot complete channel preparation while the SDCA Function
> is powered down: the peripheral raises the channel's bit in
> DPn_PrepareStatus and never clears it.

...

> Power the Function up in the PRE_PREP callback, immediately before the
> PrepareCtrl write it already performs, so that preparation has what it
> needs on every path that prepares a port.

>  	case SDW_OPS_PORT_PRE_PREP:
> +		/*
> +		 * The Function has to be powered before the port can complete
> +		 * channel preparation.  hw_params() does that when a stream is
> +		 * set up, but a stream that is only re-prepared - as userspace
> +		 * does after the peripheral lost power in S0i3 - does not go
> +		 * through hw_params() again, and the peripheral is back at its
> +		 * PS3 reset default.  Power it up here, where it is needed.
> +		 */
> +		scoped_guard(mutex, &tas_dev->pde_lock)
> +			ret = regmap_write(tas_dev->regmap,
> +					   SDW_SDCA_CTL(1, TAS2783_SDCA_ENT_PDE23,
> +							TAS2783_SDCA_CTL_REQ_POW_STATE, 0),
> +					   TAS2783_SDCA_POW_STATE_ON);
> +		if (ret) {
> +			dev_err(dev, "power up failed for port %d, err=%d\n",
> +				prep_ch->num, ret);
> +			return ret;
> +		}

Does this DTRT if userspace restartss the stream by directly calling
SNDRV_PCM_IOCTL_RESUME (AMD adverise SNDR_PCM_INFO_RESUME...)?
Similarly we can suspend while prepared.  Either something needs to
force us to prepare again or this needs to be moved somewhere that's
always called.

> +
>  		ret = sdw_write_no_pm(slave, addr, prep_ch->ch_mask);
>  		if (ret)
>  			dev_err(dev, "prep failed for port %d, err=%d\n",
> 
> base-commit: 6f6fb37f9f9a8ae88faa1b5b1978e57381488502
> -- 
> 2.53.0
>

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