linux-kernel - Re: [PATCH] ASoC: fsl_ssi: Fix mode setting when changing channel number

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Message-ID: <757bf30b-60fc-5ff8-e9b3-7978bae2264d@nextfour.com>
Date:   Mon, 9 Apr 2018 09:55:11 +0300
From:   Mika Penttilä <mika.penttila@...tfour.com>
To:     Nicolin Chen <nicoleotsuka@...il.com>, broonie@...nel.org
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        alsa-devel@...a-project.org, tiwai@...e.com, perex@...ex.cz,
        lgirdwood@...il.com, fabio.estevam@....com, timur@...i.org
Subject: Re: [PATCH] ASoC: fsl_ssi: Fix mode setting when changing channel
 number

On 04/08/2018 07:40 AM, Nicolin Chen wrote:
> This is a partial revert (in a cleaner way) of commit ebf08ae3bc90
> ("ASoC: fsl_ssi: Keep ssi->i2s_net updated") to fix a regression
> at test cases when switching between mono and stereo audio.
> 
> The problem is that ssi->i2s_net is initialized in set_dai_fmt()
> only, while this set_dai_fmt() is only called during the dai-link
> probe(). The original patch assumed set_dai_fmt() would be called
> during every playback instance, so it failed at the overriding use
> cases.
> 
> This patch adds the local variable i2s_net back to let regular use
> cases still follow the mode settings from the set_dai_fmt().
> 
> Meanwhile, the original commit of keeping ssi->i2s_net updated was
> to make set_tdm_slot() clean by checking the ssi->i2s_net directly
> instead of reading SCR register. However, the change itself is not
> necessary (or even harmful) because the set_tdm_slot() might fail
> to check the slot number for Normal-Mode-None-Net settings while
> mono audio cases still need 2 slots. So this patch can also fix it.
> And it adds an extra line of comments to declare ssi->i2s_net does
> not reflect the register value but merely the initial setting from
> the set_dai_fmt().
> 
> Reported-by: Mika Penttilä <mika.penttila@...tfour.com>
> Signed-off-by: Nicolin Chen <nicoleotsuka@...il.com>
> Cc: Mika Penttilä <mika.penttila@...tfour.com>
> ---
>  sound/soc/fsl/fsl_ssi.c | 14 +++++++++++---
>  1 file changed, 11 insertions(+), 3 deletions(-)
> 
> diff --git a/sound/soc/fsl/fsl_ssi.c b/sound/soc/fsl/fsl_ssi.c
> index 0823b08..89df2d9 100644
> --- a/sound/soc/fsl/fsl_ssi.c
> +++ b/sound/soc/fsl/fsl_ssi.c
> @@ -217,6 +217,7 @@ struct fsl_ssi_soc_data {
>   * @dai_fmt: DAI configuration this device is currently used with
>   * @streams: Mask of current active streams: BIT(TX) and BIT(RX)
>   * @i2s_net: I2S and Network mode configurations of SCR register
> + *           (this is the initial settings based on the DAI format)
>   * @synchronous: Use synchronous mode - both of TX and RX use STCK and SFCK
>   * @use_dma: DMA is used or FIQ with stream filter
>   * @use_dual_fifo: DMA with support for dual FIFO mode
> @@ -829,16 +830,23 @@ static int fsl_ssi_hw_params(struct snd_pcm_substream *substream,
>  	}
>  
>  	if (!fsl_ssi_is_ac97(ssi)) {
> +		/*
> +		 * Keep the ssi->i2s_net intact while having a local variable
> +		 * to override settings for special use cases. Otherwise, the
> +		 * ssi->i2s_net will lose the settings for regular use cases.
> +		 */
> +		u8 i2s_net = ssi->i2s_net;
> +
>  		/* Normal + Network mode to send 16-bit data in 32-bit frames */
>  		if (fsl_ssi_is_i2s_cbm_cfs(ssi) && sample_size == 16)
> -			ssi->i2s_net = SSI_SCR_I2S_MODE_NORMAL | SSI_SCR_NET;
> +			i2s_net = SSI_SCR_I2S_MODE_NORMAL | SSI_SCR_NET;
>  
>  		/* Use Normal mode to send mono data at 1st slot of 2 slots */
>  		if (channels == 1)
> -			ssi->i2s_net = SSI_SCR_I2S_MODE_NORMAL;
> +			i2s_net = SSI_SCR_I2S_MODE_NORMAL;
>  
>  		regmap_update_bits(regs, REG_SSI_SCR,
> -				   SSI_SCR_I2S_NET_MASK, ssi->i2s_net);
> +				   SSI_SCR_I2S_NET_MASK, i2s_net);
>  	}
>  
>  	/* In synchronous mode, the SSI uses STCCR for capture */
> 

This patch fixes my problems, so: 

Tested-by: Mika Penttilä <mika.penttila@...tfour.com>


--Mika