linux-kernel - Re: [PATCH v1 01/15] ASoC: fsl_ssi: Clean up set_dai_tdm

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Date:   Mon, 1 Jan 2018 19:39:52 +0100
From:   "Maciej S. Szmigiero" <mail@...iej.szmigiero.name>
To:     Nicolin Chen <nicoleotsuka@...il.com>
Cc:     timur@...i.org, broonie@...nel.org, linux-kernel@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, alsa-devel@...a-project.org,
        lgirdwood@...il.com, fabio.estevam@....com, caleb@...me.org,
        arnaud.mouiche@...oxia.com, lukma@...x.de, kernel@...gutronix.de
Subject: Re: [PATCH v1 01/15] ASoC: fsl_ssi: Clean up set_dai_tdm_slot()

On 19.12.2017 18:00, Nicolin Chen wrote:
> This patch replaces the register read with ssi->i2s_net for
> simplification. It also removes masking SSIEN from scr value
> since it's handled later by regmap_update_bits() to set this
> scr value back.
> 
> Signed-off-by: Nicolin Chen <nicoleotsuka@...il.com>
> ---
>  sound/soc/fsl/fsl_ssi.c | 7 ++-----
>  1 file changed, 2 insertions(+), 5 deletions(-)
> 
> diff --git a/sound/soc/fsl/fsl_ssi.c b/sound/soc/fsl/fsl_ssi.c
> index aecd00f..ed2712b 100644
> --- a/sound/soc/fsl/fsl_ssi.c
> +++ b/sound/soc/fsl/fsl_ssi.c
> @@ -1051,9 +1051,7 @@ static int fsl_ssi_set_dai_tdm_slot(struct snd_soc_dai *dai, u32 tx_mask,
>  	}
>  
>  	/* The slot number should be >= 2 if using Network mode or I2S mode */
> -	regmap_read(regs, REG_SSI_SCR, &val);
> -	val &= SSI_SCR_I2S_MODE_MASK | SSI_SCR_NET;
> -	if (val && slots < 2) {
> +	if (ssi->i2s_net && slots < 2) {
>  		dev_err(dai->dev, "slot number should be >= 2 in I2S or NET\n");
>  		return -EINVAL;
>  	}

Are you sure that ssi->i2s_net SSI_SCR_I2S_MODE_MASK | SSI_SCR_NET bits
(also known as SSI_SCR_I2S_NET_MASK) zero or non-zero status is always
consistent with that in the SCR register?

I can see that in fsl_ssi_hw_params() these bits in SCR are zeroed in
a one special case and in the second special case they are hardcoded
to SSI_SCR_I2S_MODE_NORMAL | SSI_SCR_NET, in both cases regardless of
what is currently in ssi->i2s_net.

Maciej