linux-kernel - RE: [PATCH 2/4] ASoC: sh: rz-ssi: Update interrupt handling for half duplex channels

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Date:   Sat, 18 Feb 2023 08:15:14 +0000
From:   Biju Das <biju.das.jz@...renesas.com>
To:     Prabhakar <prabhakar.csengg@...il.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Magnus Damm <magnus.damm@...il.com>,
        Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.com>
CC:     "alsa-devel@...a-project.org" <alsa-devel@...a-project.org>,
        "linux-renesas-soc@...r.kernel.org" 
        <linux-renesas-soc@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Prabhakar Mahadev Lad <prabhakar.mahadev-lad.rj@...renesas.com>
Subject: RE: [PATCH 2/4] ASoC: sh: rz-ssi: Update interrupt handling for half
 duplex channels

Hi Prabhakar,

Thanks for the patch.

> Subject: [PATCH 2/4] ASoC: sh: rz-ssi: Update interrupt handling for half
> duplex channels
> 
> From: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> 
> For half duplex channels we dont have separate interrupts for Tx and Rx
> instead we have single interrupt Rt (where the signal for Rx and Tx is
> muxed). To handle such a case install a handler in case we have a dma_rt
> interrupt specified in the DT for the PIO mode.
> 
> Note, for backward compatibility we check if the Rx and Tx interrupts are
> present first instead of checking Rt interrupt.

Just a thought, 

As dt-binding doc mentions, a way to distinguish half duplex and full duplex by
Counting the number of interrupts. Maybe we could use that property for
detecting channel with full/half duplex mode.

See below

> 
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> Reviewed-by: Biju Das <biju.das.jz@...renesas.com>
> ---
>  sound/soc/sh/rz-ssi.c | 63 ++++++++++++++++++++++++++++++-------------
>  1 file changed, 44 insertions(+), 19 deletions(-)
> 
> diff --git a/sound/soc/sh/rz-ssi.c b/sound/soc/sh/rz-ssi.c index
> 5d6bae33ae34..d502aa55c5a8 100644
> --- a/sound/soc/sh/rz-ssi.c
> +++ b/sound/soc/sh/rz-ssi.c
> @@ -109,6 +109,7 @@ struct rz_ssi_priv {
>  	int irq_int;
>  	int irq_tx;
>  	int irq_rx;
> +	int irq_rt;
> 
>  	spinlock_t lock;
> 
> @@ -565,6 +566,17 @@ static irqreturn_t rz_ssi_interrupt(int irq, void
> *data)
>  		rz_ssi_reg_mask_setl(ssi, SSIFSR, SSIFSR_RDF, 0);
>  	}
> 
> +	if (irq == ssi->irq_rt) {
> +		struct snd_pcm_substream *substream = strm->substream;
> +
> +		if (rz_ssi_stream_is_play(ssi, substream)) {
> +			strm->transfer(ssi, &ssi->playback);
> +		} else {
> +			strm->transfer(ssi, &ssi->capture);
> +			rz_ssi_reg_mask_setl(ssi, SSIFSR, SSIFSR_RDF, 0);
> +		}
> +	}
> +
>  	return IRQ_HANDLED;
>  }
> 
> @@ -993,26 +1005,39 @@ static int rz_ssi_probe(struct platform_device *pdev)
>  	if (!rz_ssi_is_dma_enabled(ssi)) {

Here, Detect Half duplex or full duplex by counting number of interrupts.

If half duplex get IRQ associated with dma_rt

If full duplex get IRQ associated with dma_rx and dma_tx.

>  		/* Tx and Rx interrupts (pio only) */
>  		ssi->irq_tx = platform_get_irq_byname(pdev, "dma_tx");
> -		if (ssi->irq_tx < 0)
> -			return ssi->irq_tx;
> -
> -		ret = devm_request_irq(&pdev->dev, ssi->irq_tx,
> -				       &rz_ssi_interrupt, 0,
> -				       dev_name(&pdev->dev), ssi);
> -		if (ret < 0)
> -			return dev_err_probe(&pdev->dev, ret,
> -					     "irq request error (dma_tx)\n");
> -
>  		ssi->irq_rx = platform_get_irq_byname(pdev, "dma_rx");
> -		if (ssi->irq_rx < 0)
> -			return ssi->irq_rx;
> -
> -		ret = devm_request_irq(&pdev->dev, ssi->irq_rx,
> -				       &rz_ssi_interrupt, 0,
> -				       dev_name(&pdev->dev), ssi);
> -		if (ret < 0)
> -			return dev_err_probe(&pdev->dev, ret,
> -					     "irq request error (dma_rx)\n");
> +		if (ssi->irq_tx == -ENXIO && ssi->irq_rx == -ENXIO) {
> +			ssi->irq_rt = platform_get_irq_byname(pdev, "dma_rt");
> +			if (ssi->irq_rt < 0)
> +				return ssi->irq_rt;
> +
> +			ret = devm_request_irq(&pdev->dev, ssi->irq_rt,
> +					       &rz_ssi_interrupt, 0,
> +					       dev_name(&pdev->dev), ssi);
> +			if (ret < 0)
> +				return dev_err_probe(&pdev->dev, ret,
> +						"irq request error (dma_tx)\n");

Typo dma_rt??

Cheers,
Biju

> +		} else {
> +			if (ssi->irq_tx < 0)
> +				return ssi->irq_tx;
> +
> +			if (ssi->irq_rx < 0)
> +				return ssi->irq_rx;
> +
> +			ret = devm_request_irq(&pdev->dev, ssi->irq_tx,
> +					       &rz_ssi_interrupt, 0,
> +					       dev_name(&pdev->dev), ssi);
> +			if (ret < 0)
> +				return dev_err_probe(&pdev->dev, ret,
> +						"irq request error (dma_tx)\n");
> +
> +			ret = devm_request_irq(&pdev->dev, ssi->irq_rx,
> +					       &rz_ssi_interrupt, 0,
> +					       dev_name(&pdev->dev), ssi);
> +			if (ret < 0)
> +				return dev_err_probe(&pdev->dev, ret,
> +						"irq request error (dma_rx)\n");
> +		}
>  	}
> 
>  	ssi->rstc = devm_reset_control_get_exclusive(&pdev->dev, NULL);
> --
> 2.25.1