Re: [alsa-devel] [PATCH 3/8] ASoC: tegra: i2s: Add support for more than 2 channels

[Jon Hunter <jonathanh@nvidia.com>]

On 17/09/2019 19:12, Ben Dooks wrote:
> From: Edward Cragg <edward.cragg@codethink.co.uk>
> 
> The CIF configuration and clock setting is currently hard coded for 2
> channels. Since the hardware is capable of supporting 1-8 channels add
> support for reading the channel count from the supplied parameters to
> allow for better TDM support. It seems the original implementation of this
> driver was fixed at 2 channels for simplicity, and not implementing TDM.
> 
> Signed-off-by: Edward Cragg <edward.cragg@codethink.co.uk>
> [ben.dooks@codethink.co.uk: added is_tdm and channel nr check]
> ---
>  sound/soc/tegra/tegra30_i2s.c | 21 +++++++++++++--------
>  sound/soc/tegra/tegra30_i2s.h |  1 +
>  2 files changed, 14 insertions(+), 8 deletions(-)
> 
> diff --git a/sound/soc/tegra/tegra30_i2s.c b/sound/soc/tegra/tegra30_i2s.c
> index b5372839f672..40bcc05a9dbb 100644
> --- a/sound/soc/tegra/tegra30_i2s.c
> +++ b/sound/soc/tegra/tegra30_i2s.c
> @@ -86,14 +86,17 @@ static int tegra30_i2s_set_fmt(struct snd_soc_dai *dai,
>  		return -EINVAL;
>  	}
>  
> +	i2s->is_tdm = false;
>  	mask |= TEGRA30_I2S_CTRL_FRAME_FORMAT_MASK |
>  		TEGRA30_I2S_CTRL_LRCK_MASK;
>  	switch (fmt & SND_SOC_DAIFMT_FORMAT_MASK) {
>  	case SND_SOC_DAIFMT_DSP_A:
> +		i2s->is_tdm = true;
>  		val |= TEGRA30_I2S_CTRL_FRAME_FORMAT_FSYNC;
>  		val |= TEGRA30_I2S_CTRL_LRCK_L_LOW;
>  		break;
>  	case SND_SOC_DAIFMT_DSP_B:
> +		i2s->is_tdm = true;
>  		val |= TEGRA30_I2S_CTRL_FRAME_FORMAT_FSYNC;
>  		val |= TEGRA30_I2S_CTRL_LRCK_R_LOW;
>  		break;
> @@ -127,10 +130,13 @@ static int tegra30_i2s_hw_params(struct snd_pcm_substream *substream,
>  	struct device *dev = dai->dev;
>  	struct tegra30_i2s *i2s = snd_soc_dai_get_drvdata(dai);
>  	unsigned int mask, val, reg;
> -	int ret, sample_size, srate, i2sclock, bitcnt, audio_bits;
> +	int ret, sample_size, srate, i2sclock, bitcnt, audio_bits, channels;
>  	struct tegra30_ahub_cif_conf cif_conf;
>  
> -	if (params_channels(params) != 2)
> +	channels = params_channels(params);
> +	if (channels > 8)
> +		return -EINVAL;
> +	if (channels != 2 && !i2s->is_tdm)

I don't think that this additional test is really necessary. I would
just drop this 'is_tdm' variable.

Cheers
Jon

-- 
nvpublic
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